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Reporting a new invasive species sighting


Please report invasive species found at new locations to:

Minimum information requirements:

  • Sample (or photo capturing key features) to confirm ID
  • Date collected/observed
  • Location collected/observed (GPS coordinates preferred)
  • Contact information


What to do if you find an invasive species:

Write down the location of where you found the species before you forget. We really want longitudinal and latitudinal coordinates. However, if (like most people) you do not have the coordinates, look for landmarks or other things that can help us distinguish exactly where you found the organism. For example: "within 2 yards of the public beach boat access on Green Lake".

Take a sample (leaf, shell, etc) and/or a picture of the organisms. This will help us confirm your identification.

Please check the GLANSIS database to make sure that the organism you have found has not already been found in your location. To do this:

  1. Enter the common name into the search field and click Submit
  2. Click on the scientific name to bring up the fact sheet
  3. Scroll to the link which reads Great Lakes Region Collection Information and click to bring up all the locations where that organism has been found.
  4. Browse the list to look for your location

If your organism cannot be found in the database congratulations! You may have found an invasive species and now must report your discovery! One way you can do so is by going to the USGS Nonindigenous Aquatic Species Sighting Report Form which will send an email report of your discovery.

Why we need your help finding invasive species

Image of lake
  • There are more than 187 species
  • There are 94,000 square miles of water
  • There are 200,000 square miles of land in the basin
  • There are only about 100 dedicated AIS biologists in the region

We appreciate your assistance!

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Guidelines to Prevent the Spread of Aquatic Invasive Species

Based on Guidelines by the Recreational Activities Committee of the ANS Task Force in 2000 and the National Habitattitude Campaign

Guidelines revised based on input of members of the Great Lakes Panel (April 2010) and members of the Great Lakes Panel Information/Education Committee (June 2010)

*Regulations vary by state and region. Please check for local laws and guidelines before operating in unfamiliar waters.

Approval Pending by: Great Lakes Panel on Aquatic Nuisance Species

Boaters and Anglers

Before launching…before leaving:

  • Inspect and remove aquatic plants, fish, animals, and mud from boat, motor, trailer, and equipment
  • Drain water from boat, motor, bilge, livewell, and bait containers
  • Dispose of unwanted live bait, fish parts, and worms in the trash
  • Spray/rinse boat and equipment with high pressure or hot (120F/50C or higher)water on your way home or at home, or
  • Dry everything for at least five days before going to another water body


Before launching…before leaving:

  • Inspect and remove aquatic plants, animals and mud from hull, centerboard and bilgeboard wells, rudderpost area, and trailer
  • Drain water from motor and bilge
  • Spray/rinse watercraft and equipment with high pressure or hot water (120F/50C or higher), OR
  • Dry everything for at least 5 days before going to another water body

Personal Watercraft Users

At the water access before leaving:

  • Avoid running engine through aquatic plants
  • Push or winch the watercraft onto the trailer without running engine

On the trailer:

  • Run engine for 5-10 seconds to blow out excess water and vegetation from internal drive, then turn off engine
  • Inspect and remove aquatic plants, animals and mud from water intake grate, steering nozzle, watercraft hull, and trailer
  • Wash/rinse watercraft and equipment with high pressure or hot water (120F/50C or higher), or
  • Dry everything for at least 5 days before going to another water

Scuba Divers

Before diving…before leaving:

  • Inspect and remove aquatic plants, animals, and mud from gear including wetsuits, masks, snorkels, boat, motor, and trailer
  • Drain water from buoyancy compensator (bc), regulator, tank boot, boat and trailer
  • Spray/rinse suit and inside of bc with hot water (120F/50C or higher) or salted water (1/2 cup/gallon) followed by a clean freshwater rinse, OR
  • Dry everything for at least 5 days before going to another water

Seaplane Operators

Before take-off:

  • Inspect and remove aquatic plants, animals and mud from floats, rudders, cables, transom, chine, wheel wells, and step area
  • Pump water from floats
  • Avoid taxiing through heavy growths of aquatic plants
  • Raise and lower rudders several times to free aquatic plants

After take-off:

  • Raise and lower rudders while over waters you are leaving or over land – if plants remain, return to that waterbody to remove

Regular Maintenance:

Use one or more method below:

  • Spray/rinse floats with high pressure or hot water (120F/50C or higher)
  • Scrub/scrape undersides of floats (when spraying or drying is not possible), especially if moored for more than a day
  • Dry floats by storing aircraft on land for at least 5 days before going to another water

Waterfowl Hunters

Before hunting…after hunting:

  • Inspect and remove aquatic plants, animals, and mud from boat, motor, trailer, waders or hip boots, decoy lines, and anchors*
  • Drain water motor, livewell and bilge
  • Spray/rinse watercraft and equipment with high pressure or hot water (120F/50C or higher), especially if moored for more than a day, OR
  • Dry everything for at least 5 days before going to another water

* use elliptical, bulb-shaped or strap anchors on decoys to help avoid snagging aquatic plants

Aquarists and Water Gardeners*

Alternatives to release:

  • Contact a retailer for proper handling advice or possible returns
  • Give or trade with another aquarist, pond owner, or water gardener
  • Donate to a local aquarium society, school, or aquatic business
  • Seal aquatic plants in plastic bags and dispose in the trash
  • Contact a veterinarian or pet retailer for guidance on humane disposal of animals

* guidelines developed by Habitattitude campaign

Note: Use guidelines in accordance with appropriate local, state, provincial and federal regulations

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This glossary includes definitions for the technical terminology used in GLANSIS research.



Abalone - A flattened, ear-shaped shell with a nacreous interior; a member of the family Haliotidae. Called “Paua” in New Zealand.

Abapical - Away from shell apex toward base along axis or slightly oblique to it.

Abaxial - situated away from main axis, often on underside of branch

Abciss - detach, separate from main structure

Abdomen (n), (adj. abdominal) - In vertebrates the abdomen (belly) constitutes the part of the body between the thorax (chest) and pelvis. In arthropods the abdomen is last section of the body which lies behind the thorax or cephalothorax.

Abdominal Distension (n) - Swelling of the stomach area caused by internal injury or malnutrition.

Aberrant - Deviating from the usual type of its group; abnormal, straying, different.

Abiotic (adj) - non-living

Aboral (adj) - side opposite the mouth

Abscess (n) - Symptom consisting of a localized collection of pus surrounded by inflamed tissue.

Abundance (n) - number of organisms

Abyssal - Associated with the abyssal zone, i.e., the floor of the deeper ocean from 2,000 to 6,000 meters.

Accessory - subsidiary, like a non-chlorophyll pigment

Accessory plate - A secondary calcareous or corneous structure formed in some bivalves (e.g., Pholadidae) to protect the soft parts. In certain bivalves, a small shelly or partially shelly plate lying over the upper or lower margin, or a shelly plate attached to the internal ligament.

Accessory scar - In bivalves, a small, mostly circular impression on the inside of the shell made by other than the adductor and pallial muscles.

Acclimate (v) - adjust to a new climate or situation

Acetabulum (n, pl - a)- Literally, “vinegar cup”. A concave or cup-like surface. Surface of the pelvis forming the hip joint. Ventral sucker.

Acropetal - from the base to the apex

Actinodont - Descriptive of bivalve shell having a hinge with teeth that radiate outward from the umbones.

Actinophore (n) - A structure of suctorians bearing a fascicle (bundle) of tentacles.

Aculeate - bearing a sharp point

Acuminate - Gradually tapered to a point. Sharply pointed.

Acute (adj) - Sharp angle (less than 90 degrees). Rapid or short-term.

Adapt (v), adaptation (n) - change to fit the environment. Usually implies a genetic change through natural selection.

Adaxial - situated toward the axis, often on the upper side of branch

Adductor muscle impression - Impression on inside of bivalve shell valves where the adductor muscle was attached. See Adductor Scar.

Adductor muscle(s) - Anterior and posterior muscles that close a bivalve shell. In a bivalve, the muscle, either one or two, connecting valves and drawing them together.

Adductor scar(s) - The depressed scars of the muscles of a bivalve shell. A differentiated area on the interior of a bivalve shell that marks the attachment point of an adductor and is generally striated, depressed, or outlined. Attachment scars of adductor muscles inside a bivalve shell

Adherent - closely attached

Adhesive - sticky

Adipose (adj) - Fat. The adipose fin is a fleshy fin between the dorsal fin and the tail.

Adpressed - Whorls overlapping. A suture tightly pressed to previous whorl. Overlapping whorls with their outer surfaces very gradually converging; preferred to the term appressed.

Adventitious - irregular, secondarily produced, not a primary part

Aerate (v) - mix in air

Aerobic (adj) - requiring air

Aerola (n) - Small, circular area (plural: Aerolae)

Aerolae (n) - see Aerola

Aerosol (n) - very fine airborne droplets.

Aesthetascs - sensory processes on the antennules (first pair of antennae) of crustaceans. Aesthetascs may be small or large and shaped as filaments, cylinders, or flasks.

Affix (v) - attach

Agar (n), agarose (adj) - A sugar galactose polymer obtained from the cell walls of some species of red algae or seaweed. Its chief use is as a culture medium for microbiological work.

Aggregation - a grouping of algal cells but not the organization of a colony, often held together by mucilage

Agonistic (adj) - defensive social interaction

Akaryotic - without a true nucleus

Akinete - enlarged cell with food reserves and thick cell wall which may undergo dormancy, e.g. in Cyanobacteria

Akinete (n) - a thick walled cell able to withstand dessication.

Albumen (n) - egg white

Alga (-ae) - a term for a very diverse taxonomic group all containing chlorophyll a but lacking vascular tissues found in higher plants; may be unicellular or multicellular organisms, found in marine, freshwater, living endophytically in other plants and algae, soil environments, some can even by airborne. This course focuses on freshwater algae found in the following phyla: Cyanophyta (blue-greens), Chlorophyta (greens), Euglenophyta (flagellated greens), Pyrrhophyta (dinoflagellates), Chrysophyta (browns, yellow-greens, diatoms) and the Rhodophyta (reds).

Algal bloom - A condition which occurs when excessive nutrient levels and other physical and chemical conditions facilitate rapid growth of algae. Algal blooms may cause changes in water color. The decay of the algal bloom may reduce dissolved oxygen levels in the water.

Alginate - salt form of alginic acid, a polysaccharide colloid produced in walls of Phaeophyceae made of mannuronic acid and guluronic acid units

Alkabiontic (adj) - requiring alkaline (pH above 7) conditions

Alkaline - Acting like a base; having a pH of more than 7.

Alkalinity (n) - measure of the ability of a solution to neutralize acids. Sum of the bases in solution.

Alkalphilic (adj) - alkalinity-loving. preferring alkaline (high ph) environments

Allelopathy (n), allelopathic (adj) - process by which one organism releases a chemical that harms another. Most common in plants.

Allochthonous (adj) - found in a place other than where they were formed.

Allometric (adj) - changing shape with growth.

Alloparasite - parasite not related to its host

Allopatric (adj) - occurring in separate, nonoverlapping geographic areas.

Alpine (adj) - mountain zone between the treeline and permanent snowline.

Alternate - branched at different levels on opposite sides of main axis

Ammocoete (n) - blind larvae of a lamprey

Amoeba (n, pl - ae) - shapeless unicellular animal-like protozoan which moves by pseudopods

Amorphous - lacking definite structure or shape

Amphi- (prefix) - 2-sides or 2 natures.

Amphi Atlantic - (adj.) Found on both sides of the northern Atlantic, along the seaboards of eastern North America and Europe.

Amphibian (n) - a member of the class Amphibia, which includes frogs and salamanders. A vertebrate animal which begins life as an aquatic larvae with gills and transforms to a terrestrial or semi-terrestrial adult with lungs.

Amphineura - One of six classes of mollusca; chitons or coat-of-mail shells.

Amphipod - (n) An omnivorous member of a group of small crustaceans that includes shrimp, sea lice and sand fleas.

Ampulla (n, pl - ae) - A small vessel or bottle. A small opening in a canal or duct. A dilated segment in a tubular structure.

Amyloplast - colorless organelle related to starch production

Anadromous (adj) - migrating upstream to breed, usually from saltwater to freshwater.

Anaerobic - Any process that can occur without molecular oxygen; also applicable to organisms that can survive without free oxygen.

Anaerobiosis (n) - Life sustained in the absence of air (oxygen)

Anal canal - An opening in the gastropod shell through which excrement is expelled.

Anal somite - last segment of the body, bearing dorsally the anal operculum which protects the anus, and distally the paired caudal rami.

Anal - Pertaining to or near the anus, or posterior opening of the alimentary canal.

Analog - An organism analogous to one in another species group; having a similar function but different in origin and structure.

Anemia (n) -ic (adj) - literally ‘without blood’. Deficiency of red blood cells.

Angler (n) - a fisherman using a hook and line.

Angular or Angulate - Cornered, two surfaces meeting at an angle. Having angles, sharp corners, or an edge where two surfaces meet at an angle.

Anisogamete (n) - a gamete differing in size or structure from the one with which it unites.

Anisogamy - reproduction by motile gametes that differ in morphology or behavor

Anisomyarian - Descriptive of bivalve shells with the scars of the two adductor muscles on the interior being of different sizes. The posterior scar is usually larger than the anterior.

Anistrophic - a shell which is spirally coiled and is asymmetrical.

Annelid (n, adj) - member of the Phylum Annelida, segmented worms.

Annual - (adj) yearly. (n) A plant that sets seed every year and dies.

Annulated - Marked with rings.

Annulation or Annular ring - A growth increment in a tubular shell marked by regular constrictions (e.g., caecum).

Anomphalous - Lacking umbilicus. Antepenultimate whorl:. Last whorl but one, before body whorl.

Anorexia (n) - loss of appetite

Anoxia (n) - no oxygen

Antapical - Pertaining to the posterior or rear of a dinoflagellate (the hypotheca).

Ante- (prefix) - before

Antenna (n, pl -ae) antennal (adj) - sensory organ. Usually located on top of

Antennule (n) - small antenna or antenna-like structure.

Antepenultimate (adj) - before the next to the last (3rd from the end)

Anterior - in front, or toward the front

Anterior canal - Notch or through-like or tubular extension of anterior apertural margin supporting the incurrent or inhalant siphon. See also Siphon Canal.

Anterior extremity or margin - Front or head end of animal or shell. In gastropod shells it is the front or head end of the animal, i.e. the opposite end of the apex of the shell; in bivalves the anterior margin is on the opposite side of the ligament, i.e. where the foot protrudes.

Anterior slope - Surface of valve of bivalve shell from umbo to anterior ventral margin.

Antero-dorsal surface - Dorsal surface of bivalve shell anterior to umbones.

Antheridium - cell that produces motile male gamete

Anthropogenic (adj) - of human origin, caused by humans

Antibacterial agent - (n) An agent or treatment which prevents the growth of bacteria.

Anus (n), Anal (adj) - opening of the gut through which feces are expelled

Apertural - Pertaining to aperture or on same side as aperture.

Aperture (n)- an opening. Snail anatomy: the hole in the shell through which the snail body protrudes.

Apex (n), apices (pl), apical (adj) - tip or end

Apical - at or near the apex or top, distal

Apical cavity - A space under the apex of patellate gastropods.

Apical orifice- An opening at the apex. Apical plug: A special calcareous filling in the apex of certain

Apical- At the apex, point or tip.

Apogamy - development of an organism without gamete fusion (fertilization)

Apomeiosis - nuclear division without meiosis

Appendage (n) - external body part, limb (arm or leg)

Appressed - With whorls overlapping, so that their outer surfaces converge gradually. Also given (in other works) as Adpressed.

Aquaculture (n, v) - cultivation of aquatic organisms, fish farming

Aquatic - living in the water

Aragonite - A mineral composed, like calcite, of calcium carbonate, but differing from calcite in certain characters of crystallization, density, and cleavage.

Archetype - The ancestral type established hypothetically by eliminating specialized characters of known later forms.

Archibenthic - Deep sea zone; between 800 and 1,000 metres.

Archive (n, v) - collection of historical records, to record or collect records.

Arcuate - curved like a bow, crescent-shaped

Areola (n, pl -ae) - small circular area. hole in a diatom valve.

Artesian (adj) - An aquifer or well that produces water without the need for pumping due to natural pressure.

Arthropod (n, adj) - literally, joint-foot. A member of the phylum Arthropoda, which includes insects, arachnids and crustacea. Invertebrates with a hard chitonous exoskeleton, a segmented body with appendages

Articulamentum - Internal layer of a chiton shell. In chitons, the middle shell layer.

Articulated - jointed or segmented, e.g. Calliarthron or Halimeda

Asexual (adj) - without sex. Reproduction with only one parent and no mixing of genes producing offspring identical to the parent.

Assemblage (n) - Collection: several things grouped together or considered as a whole.

Assimilate (v) - absorb, incorporate, adapt or adjust.

Asymmetrical (adj) - not symmetrical

Asymptomatic (adj) - not showing symptoms

Asymptotic (adj) - approaching a value, curve, limit or infinity

Attachment scar - Any impression left on a molluscan shell by the attachment of a soft part (e.g., mantle, muscle, or foot).

Attenuate (v, adj) - tapering gradually, usually to a long slender point

Atypical (adj) - not typical, not usual

Aubtropical - (adj) Refers to areas of the earth that are close to the tropics, the area near the equator, and have a climate much milder than temperate, northern zones.

Auricular (adj) - pertaining to or near the outer ear

Auricular crus - Blunt internal ridge that defines the bottom boundary of the auricles of certain bivalve shells.

Auriculate - Having ear-shaped projections.

Auriform - Shaped like a human ear.

Autotroph (n) (adj -ic) - literally self-feeding. Usually a plant or algae that make its food from sunlight

Autotrophic - capable of producing its own food

Auxiliary cell - cell in post-fertilization development in the Rhodophyta which receives the diploid (2N) zygote nucleus and then develops the gonimoblast filaments

Auxospore (n) - Special cells produced by diatoms following sexual reproduction. Auxospores return the diatom to its maximum size. May have thickened cell walls and may serve as a resting stage.

Axial sculpture - Sculpture running parallel to the axis of coiling.

Axis (n), axes (pl), axial (adj) - straight line through a body. Center of rotation. Main stem or central part about which plant organs or plant parts such as branches are arranged.



Bacillariophyte (n) -diatom, member of the phylum Bacillariophyta. Unicellular or colonial algae with silica shells fitting together like a Petri plate.

Back-crossing (v) -crossing or mating a hybrid with one of its parent types.

Bacterium (n), bacteria (pl) -unicellular organism of the Kingdom Monera. Prokaryotes in which the cells have no defined nucleus, but the genetic material (DNA) is scattered throughout the cell.

Ballast (n, v) -device or weight used to stabilize a ship, especially when it is not loaded with cargo.

Band - A strip of shell material differentiated by color or construction from the shell on either side of it.

Banding - Color marking in continuous stripes.

Barbels - A fleshy, tactile icicle-shaped projection, usually near the lips, chin or nose of a fish.

Barnacle- Not a mollusk but a Crustacean.

Basal - The lower part, bottom or base of the shell.

Basal callus - A shelly spirally-ridged thickening on the columellar base as in olive shells.

Basal fasciole - A special band on the base of a shell formed by a series of more or less curved growth lines that define the siphonal sinus (canal).

Basal fold- A fold near the anterior end of the columella on a gastropod shell.

Basal plate - A segment of the ribbon to which radula teeth are attached (e.g., in collisella).

Base (n), basal (adj) -bottom, the lowest part of an organism

Baseoendopodite - a segment formed by the fusion of the endopodite with the basipodite in leg 5 (fifth leg) of some copepod groups. Also known as the basal expansion.

Base-plate -(n) a cell adhesion molecule possibly involved in sponge cell adhesion.

Basin (n) -Bowl. Bowl shaped portion of a lake bottom (e.g., Lake Erie has 3 basins). The portion of a lake filled with water. Watershed (usually drainage basin).

Basipetal - in direction from apex to base

Basipodite - alternate term for basis.

Basis - second segment from the proximal end of a segmented appendage. In the first through fifth legs the basis is the distal segment of the protopod and bears the rami.

Bathymetric - Pertaining to the measurement of depth in bodies of water; also, pertaining to the distribution of organisms over various depths.

Bead - Small rounded knob on a rib.

Beak (n) -hard external atomical structure surrounding the mouth. The raised part of the dorsal margin of the shell; also called the umbo.

Beige -(adj) a variable color averaging light grayish yellowish brown.

Benthic -(adj) Bottom dwelling: living on the floor of the sea or lake.

Benthic deposit feeder (n) -organisms eating materials which have fallen to the bottom of a body of water.

Benthic range - Depth range below sea-level.

Benthos (n), Benthic (adj) -literally, depths of the sea. Organisms living on or in the bottom of a body of water.

Beta-mesosaprobe (n) -An organism that derives its nourishment from nonliving or decaying organic matter of intermediate nutrition

Beta-mesosaprobic -an environment with medium organic pollution intermediate between polysaprobic and oligosaprobic and with dissolved oxygen above 50% saturation.

Beta-mesotrophic (adj) -with an intermediate level of productivity

Bi- (prefix) - two

Biaxial - having two axial cell rows

Biconic or Biconical - Resembling two cones placed base to base. Having a diamond-shaped outline; expecially used in reference to gastropod shells having a spire of about the same size and shape as the body whorl.

Biennial (adj) -every two years. (n) a plant which produces flowers every second year.

Bifid - cleft or divided into two parts; forked.

Bifid (n, adj) -split in two forked.

Biflagellate -(adj) having two flagella (cells).

Bifurcate (v, adj) -split into 2 parts.

Bilaterally symmetric (adj) -with two halves which are mirror images

Bilobed (v, adj) -with 2 lobes

Binary fission - a single cell doubling it's nuclear material and then dividing into two cells (asexual reproduction)

Binominal nomenclature - Two-name system of naming (i.e. generic and specific name).

Binucleate (adj) -with 2 nuclei

Bio- (prefix) - life

Bioaccumulate (v) -to accumulate or concentrate in living tissue or within a food web

Biochemical (adj) -chemical found in or produced by a living organism

Biocontrol (n, v)-control using biological means. Usually implies deliberately introducing one type of organism to control another.

Biodeposition (n)-process by which living organisms deposit materials which fall to the sediment.

Biofouling (n, adj, v)-biological fouling. Undesirable accumulation of organisms on underwater objects including ship hulls, intake pipes, etc.

Bioindicator (n) -organism used to monitor the health or status of an environment. Organisms which change substantially (noticeably) in the presence of a small or difficult to measure change in the environment make good bioindicators.

Biomagnification (n) -increase in concentration of a substance (especially a pollutant) as it moves up the food chain

Biomass (n) -the mass (weight) of a living organism or organisms

Biomonitor (n) -similar to a bioindicator, but the correlation between the indicator and environmental variable is sufficiently strong to quantify the impact.

Biordinal (adj) -Second order or two orders. Second in order.

Biordinal crochets -(n) Crochets of two lengths which occur in alternating placement.

Biosedimentation (n) -process by which living organisms contribute to the building of soils or sediments.

Biovolume -(n) volume of living material. 2. Cell’s volume.

Bipectinate (v, adj) -branching on both sides.

Biramous (adj) -branched into two main parts

Biseriate (adj) -arranged in two rows, with cells arranged in two rows

Bisporangia - sporangia that divides to produce 2 spores perhaps by mitotic division, in Corallinales and some other Rhodophyta

Bivalve (n, adj) -with two shells. Organisms of the Class Bivalvia, which includes clams and mussels.

Blade - flat, leaf-like structure

Bloom (n, v) -Sudden or prolific growth.

Blue-green alga (n) -also known as cyanobacteria. Photosynthetic prokaryotes.

Body Whorl - Last and usually the largest whorl of the gastropod shell. It is the section closest to the aperture and encloses most of the body of the animal.

Boreal - northern, colder waters

Bothridium (n) bothridia (pl) - hooked holdfasts

Brachiopod - Two-valved marine animals which somewhat resemble bivalve mollusks but do not belong in the Mollusca.

Brachypterous (adj) - Having very short or rudimentary wings

Brackish (adj)-intermediate salinity between fresh and marine salt concentrations

Bract (n) -specialized leaf from which the flower arises

Bradytictic (adj) -long-term brooding. Mussels spawning in the late summer which brood their glochidia over the winter, and release them in the early spring.

Branched -(adj) bifurcate: resembling a fork; divided or separated into two branches.

Branchia - Molluscan gill or respiratory organ.

Branchial cavity - cavity in fish that contains the gills.

Branchlet (n) -small branch, subbranch, branch off another branch.

Bridged - Extending from one side to the other; partly covered.

Bryozoa - Moss-like sea animals.

Brood (n, v) -young hatched or cared for at one time. To care for young.

Brood pouch (n) - Sac-like cavity in the parents body in which eggs are deposited and fertilized and larvae develop

Bryozoa (n) -members of Phylum Bryozoa also known as Ectoprocta. Moss animals. Tiny colonial animals superficially similar to coral but more complex. Each individual in the colony has ciliated tentacles, a looped gut and an exoskeleton.

Buccal bulb - The bulging mouth extension carrying the ribbon of teeth (radula).

Buccal - Pertaining to the organs of the mouth area in gastropods, especially to the bulging flexible mass that supports the radula.

Budding - Pinching off of a small part of the parent to form a new organism; a form of asexual reproduction.

Bulbil (n) -little bulb.

Bulbous (adj) -bulb-shaped

Bulla - in female Lernaeopodidae, a nonliving structure that anchors the copepod to the host. It is secreted by head and maxillary glands, and the maxillae become permanently attached to it.

Buoyancy (n) -capacity to float

Buoyant - Floats easily, and is less dense than water.

Buttress - A shell-strengthening structure--e.g., a supporting laminar costa in gastropods, or a support for part of the hinge in bivalves.

Byssus (n), byssi (pl), byssal (adj) -adhesive threads secreted by mussels. The organ which secretes them.



Caecum (n), caeca (pl) - a saclike cavity with only one opening

Calcareous (adj) - a sediment, sedimentary rock, or soil type which is formed from or contains a high proportion of calcium carbonate in the form of calcite or aragonite

Calcified - (adj) Hardened from the deposit of calcium salts; become unchanging or inflexible.

Callum - Shell material filling the gap between valves in certain mature pholad bivalves.

Callus - abnormal, thickened part often a reaction of wounding

Canal (n) - channel. Artificial waterway.

Canaliculate - Gutter-like or channelled; applied to suture of some gastropod shells.

Cannibalism (n) - feeding on another of its own kind

Capillary (n) - any very narrow tube or channel through which a fluid can pass

Capilliform (adj) - shaped like a hair

Capitate - shaped like a head, swollen at one or both ends

Carapace (n) (alt carapax) - part of the exoskeleton that covers the cephalothorax

Carcass (n) - The dead body of an animal

Carcinogenic (adj) - cancer-causing

Cardinal (adj) - of foremost importance

Cardinal teeth - Ridges or grooves that help hold the shells of a bivalve in alignment.

Cardinal teeth - The main central teeth in bivalve shells. Projections on the hinge line, located directly below the umbones.

Cardinal - In bivalves, situated more or less in the central part of the hinge area directly below the beaks. Elevated process on hinge plate near umbo usually with corresponding socket in opposite valve.

Carina (pl. carinae): A prominent, sharp-edged ridge; same as keel.

Carinate - With a keel-like, elevated ridge, or carina.

Carnivore - consumes food from trophic levels 2 or above, i.e., animal food.

Carp Erythrodermatitis - (n) A disease of pond fish caused by Aeromonas salmonicida and characterized by ulcers of the skin and a high mortality rate. Called also carp erythrodermatitis.

Carpogonium - haploid (N) female sexual structure in Rhodophyta consisting of single cell and its extension, the trichogyne

Carposporangia - single celled structures that produce the diploid (2N) carpospores on the parasitic carposporophyte in Rhodophyta

Carpospore - non-motile diploid (2N) spores formed on parasitic carposporophyte stage of the Rhodophyta, which germinate to form tetrasporophyte stage

Carposporophyte - the diploid (2N) stage of Rhodophyta which develops after fertilization of the carpogonium

Carrier (n) - one who carries a disease, parasite, medical condition or genetic trait without showing symptoms

Cartilage (n) - a dense connective tissue.

Cartilage pit - A depression for the inner part of the ligament in bivalves.

Cartilage - A translucent, elastic tissue inside the hinge that supplements the external ligament in binding the two valves of a bivalve together, attached to the resilifers and perhaps reinforced by a calcareous coating, the lithodesma.

Cartilaginous - fleshy, but firm or even tough and leathery

Castrate (v) - action resulting in loss of reproductive capability

Caudal (adj) - tail

Caudal fin - Tail fin.

Caudal peduncle - Trunk of the tail fin.

Caudal rami - the paired, setiferous appendages on the posterior surface of the anal somite. Also known as furcal rami.

Causal (adj) - cause

Cell (n) - small compartment, basic structural and functional unit of all organisms

Cellulose (n) - an organic compound with the formula (C6H10O5)n, the structural component of the primary cell wall of green plants

Cementation - Fixation to the substrate in sessile mollusks.

Central nervous system (n) - brain and spinal cord

Central teeth - In bivalves, the hinge teeth located on the interior under the umbones.

Centric (adj) - circular or disc-like

Centric diatom - radially symmetric diatom; compare to pennate diatoms

Centrifugal - developing from the center outward

Centripetal - developing inward toward the center

Cephalic (adj) - relating to the head

Cephalic shield - the dorsal covering of the cephalosome or cephalothorax, formed by the fusion of tergites of the incorporated somites.

Cephalic tentacles - Head tentacles.

Cephalon - The anterior region of the body, comprising the first somites (antennulary to maxillary somites).

Cephalosome - the anterior 6 somites of the body covered by the dorsal cephalic shield; comprising 5 cephalic somites and the first thoracic (= maxilliped-bearing) somite.

Cephalothorax - the anterior 7 or more somites of the body covered by the dorsal shield; comprising 5 cephalic plus at least the first and second thoracic somites (those bearing the maxillipeds and first swimming legs respectively).

Cephalothorax (n) - Head and thorax. Head and chest.

Cercaria (n), cercarial (adj) - The parasitic larva of a trematode worm, having a tail that disappears in the adult stage

Cervical (adj) - Pertaining to the neck. Pertaining to the cervix (neck of the uterus).

Cestode (n) - parasitic flatworms or tapeworms in the Class Cestoda.

Chaetae (n) - bristle, especially of an annelid worm

Characeae - (n) Green algae superficially resembling horsetail ferns: stoneworts.

Charophyte - (n) The Charophyta are a division of green algae, including the closest relatives of the embryophyte plants (which include trees, mosses, ferns).

Chemorecption (n) - the physiological reception of chemical stimuli. Senses of smell and taste.

Chemosensory (n) - Sensing of chemicals. Senses of smell and taste.

Chironomid - (n) Informal name for the non-biting midges or Chironomidae, a family of true flies (Diptera). Minute, long-legged non-biting two-winged flies with piercing mouthparts; the aquatic larvae of various species are green, blue, yellow, colorless, or red (red type called bloodworms).

Chitin (n) - a long-chain polymer of a N-acetylglucosamine, a derivative of glucose. Found in many places throughout the natural world, it is the main component of the cell walls of fungi and the exoskeletons of arthropods.

Chitin or Chitinous - A tough, horny substance that, in mollusks, sometimes occurs in the radula of a gastropod; however, most horny material in mollusks is conchiolin, not chitin.

Chitinous (adj) - resembling or containing chitin

Chloride - (n) One of seven major ions in most natural waters; Increased levels of chloride will heighten the corrosive effects of water; combined with sodium, causes a salty taste.

Chlorophyll - pigment found in photosynthetic organisms, all algae have chlorophyll a; chlorophylls b, c, and d are found in one or more groups of algae

Chlorophyll A (Chla) - (n) A measurement of a specific green pigment found in all plants including microscopic plants such as algae. It is used as an estimate of algal biomass of algae.

Chloroplast - (n) cellular organelle containing chlorophyll that carries out photosynthesis.

Chromatophore - (n) Cell containing pigment granules that enable the organism to change color. An organelle that contains pigment.

Chromosome - A structure in the cell nucleus that contains DNA, histone protein, and other structural proteins.

Chronic - marked by long duration or frequent recurrence

Cilia - a hairlike projection from the surface of a cell; provides locomotion in free-swimming unicellular organisms

Cilium (plural Cilia) - A hair-like extension from the cell surface and capable of rhythmic movement. Used to designate the filaments on the mantle, in the gills, etc.

Cingulum. (pl. cingula) - In diatoms, the rings or bands of silica encircling the valves where they overlap. Also called a girdle band.

Circumboreal - comprising or throughout far northern regions

Circumpolar - Living in the waters surrounding or found in the vicinity of a terrestrial pole.

Circumtropical - Throughout the tropics.

Cladocerans - (n) Small, mostly freshwater crustaceans. Also known as waterfleas though they are not related to fleas.

Class - Major division of a phylum. There are six (or seven) classes in Mollusca.

Clathrate - Latticed with bisecting striae or cords, or by axial and spiral ridges.

Cleft - (n) An opening, fissure, or V-shaped indentation made by or as if by splitting.

Clitellata - Clitellata is a class of Annelid worms, characterized by having a clitellum - the 'collar' that forms a reproductive cocoon during part of their life cycle. The clitellates comprise around 8,000 species.

Clitellum - (n) The reproductive part of a worm that produces cocoons (worm eggs are inside cocoons).

Clone - a group of genetically identical cells or organisms derived from a single cell or individual by some kind of asexual reproduction

Cnidaria - hydras; polyps; jellyfishes; sea anemones; corals

Cobalamine - (n) Vitamin B12. a water-soluble vitamin needed for normal nerve cell activity, DNA replication, and production of the mood-affecting substance SAMe (S-adenosyl-L-methionine).

Cobble - A particular size of rock, larger than gravel

Coccoid - (adj) spherical

Coccoliths - (n) individual plates of calcium carbonate formed by coccolithophores.

Coccus - (n) Sphere (plural cocci)

Coelenterates- radially symmetrical animals having saclike bodies with only one opening and tentacles with stinging structures

Coelom - body cavity

Coelomocyte - cells in Coelom

Coenobium - a colony where the number of cells is fixed at the time of reproduction

Coenobium - a group of cells forming a structured, fixed colony such as Scenedesmus

Conjugation - sexual fusion of two ameboid cells (motile is from ameboid movement not flagella).

Calcareous - Composed mostly of calcium carbonate or lime. Chalky or shelly in appearance.

Coenocyte / Coenocytic - a multinucleate cell that does not have cellular cross walls

Coenocytic - multinucleate, without cell crosswalls, composed of multinucleate cells or segments

Co-evolve - the change of a biological object triggered by the change of a related object

Cognate - Allied by deviation from the same source.

Cohabitation - (n) The act of living together.

Coincide - happen simultaneously

Collar - A raised lip bordering a suture.

Colloquial - Regional slang.

Collumella fold - Ridge winding round columella and projecting into interior of shell.

Colonial - A kind of animal that is organized into associations (colonies) of incompletely separated individuals; e.g., Physalia, sponges and corals.

Colony - a group of individuals living and acting together, often functioning as a single individual.

Colony - a group of cells that function on one, organized unit such as Hydrodictyon

Columella - a small column (or structure resembling a column) that is a part of a snail

Columellar lip- Inner edge of the aperture comprising the visible part of the columella.

Commensal - either of two different animal or plant species living in close association but not interdependent

Community - a group of interdependent organisms inhabiting the same region and interacting with each other

Compensation point - conditions where respiration is in balance with photosynthesis, with generally no net gas exchange, in algae usually related to habitat depth

Compound - having multiple parts or branches, not simple

Compound eye - in insects and some crustaceans: composed of many light-sensitive elements each forming a portion of an image

Compound leaves - A plant with several leaves or leaflets coming from a common leaf stalk is said to have a compound leaf structure.

Compressed - flattened

Concave - curving inward

Concentric - (adj) Concentric objects share the same center, axis or origin with one inside the other. Circles, tubes, cylindrical shafts, disks, and spheres may be concentric. Concentric objects do not necessarily have the same radius. A target is a series of concentric circles.

Conceptacle - cavity or chamber containing reproductive structures with opening to the surface for release, e.g. in Corallinales and Fucales

Conchology - The study of marine, fresh-water and land-shells. The branch of zoology that embraces the arrangement and description of mollusks based upon the study of the hard parts.

Conductivity - the transmission of heat or electricity or sound

Confer - (v) To consult together; compare opinions; carry on a discussion or deliberation.

Confluent - Flowing together as to form one.

Congener - an animal or plant that bears a relationship to another

Congest - become or cause to become obstructed

Conic or Conical - Cone-shaped; especially, describing a shell with a flattened base and whorls that are so shaped.

Conspecific - an organism belonging to the same species as another organism

Conspicuous - (adj) easily seen.

Contiguous - (adj) Connected, touching, abutting; adjacent, neighboring; connecting without a break

Convex - (adj) Curving or bulging outward.

Copepod - minute marine or freshwater crustaceans usually having six pairs of limbs on the thorax; some abundant in plankton and others parasitic on fish

Copepodid - an alternate word for copepodite.

Copepodite - one of the 5 post-naupliar stages of development (C1 through C5), which have a body form resembling but simpler than the adult (C6).

Coppice dune- A mound formed by wind in conflict with bunch vegetation.

Coprophagy - eating feces

Copulate - mate

Cord(s) - Course, rounded spiral or transverse linear sculpture on the shell surface; smaller than costae.

Core - the center of an object

Corneous - Consisting of horn, of a non-calcareous hornlike texture, as the opercula of some mollusks, such as busycon.

Coronate - Encircled by a row of spines or prominent nodes, especially at the shoulder of the last whorl in gastropods.

Corrugated - Folded or ridged; broadly and heavily sculptured.

Cortex - tissue lying between the epidermis layer and the central medulla tissue

Cortical - relating to the cortex

Cosmopolitan - (adj) worldwide, or nearly so, in distribution.

Costa - a thickened portion of a diatom wall, usually elongated

Coupler - the plate or intercoxal sclerite that connects the coxae of a pair of swimming legs.

Cover cells - sterile cells cut off from during the formation of tetrasporangia in Rhodophyta

Coxa - proximalmost (closest to the body) segment of a segmented appendage.

Crenulate - having a scalloped or notched margin.

Crenules - Small notches or beads.

Crepuscular - creatures active during twilight

Crevice - a long narrow crack in a surface

Crochets - (n) Hook-like spines

Cross fertilization - fertilization by the union of male and female gametes from different individual of the same species

Crosswall - end wall of a cell in a filament

Cruciate - generally cross-shaped; in the Rhodophyta, the type of division where tetrasporangium divides in two planes at right angles to each other

Crustaceans - any mainly aquatic arthropod usually having a segmented body and chitinous exoskeleton

Cryptic - hidden or camouflaged; often applied to microscopic faunas that are concealed within a substrate, or to biological species that do not have obvious morphological differences.

Cryptogenic - of uncertain origin (we don’t know whether it is native or not)

Crystalline - transparent

Ctenidium - respiratory organ

Ctenophore - A comb jelly, a transparent gelatinous planktonic animal. Comb jellies have rows of cilia that look like combs. Unlike sea nettles and other jellyfish, comb jellies do not have stinging cells.

Cuticle - Non-cellular outer portion of the integument (skin).

Cyanobacteria - (n) Group of mostly freshwater algae with blue-green pigment; often referred to as blue-green algae; may occur as a single cell or as a colony of cells.

Cyclomorphosis - change in shape (morph) in a specific cycle, often annual.

Cylindrical - Round, like a cylinder with parallel sides.

Cyst - a small anatomically normal sac or bladder-like structure

Cyst - a general term for thick-walled vegetative cell

Cytokinesis - organic process consisting of the division of the cytoplasm of a cell following karyokinesis bringing about the separation into two daughter cells

Cytoplasm - the protoplasm of a cell excluding the nucleus; is full of proteins that control cell metabolism



Debris- detritus, the remains of something that has been destroyed or broken up

Deciduous - Having the tendency to fall off early or before maturity, as the periostracum of most Cymatium.

Decimate- kill one in every ten

Decollate - Truncated or cut off, with the earlier whorls detached, as in some gastropods.

Decompose - break down

Decussate or Decussated - Sculpture crossings at acute angles. Having a latticed surface ornamentation formed by the intersection of fine ribs, not necessarily at right angles. See also Cancellate.

Degeneration- passing from a more complex to a simpler biological form

Delimited- (adj) Having a distinct restricting edge or margin.

Deltoidal - More or less triangular.

Demersal - Species that live near the bottom of the water body.

Demographic - (adj) Of or relating to demography (the statistical study of populations)

Demographic bottleneck - (n) A significant, usually temporary, reduction in genetically effective population size, either from a population “crash” or a colonization event.

Dentate- (adj) Having toothlike projections in the margin.

Denticle - small tooth, or toothlike projection.

Depressed - Low in proportion to diameter.

Dermal- (adj) Pertaining to or affecting the skin.

Dermis- (n) The lower or inner layer of the two main layers of tissues that make up the skin.

Desiccation- (n) dehydration: dryness resulting from the removal of water.

Desmid - green algae that have conjugation of non-flagellate, amoeboid gametes

Desmokont - dinoflagellate with two flagella at the anterior end

De-stratified- (adj) lacking stratification (layering) or (v) loss of stratification.

Deterioration - a symptom of reduced quality or strength

Detrimental - causing harm or injury

Detritivore - consumes detritus, food derived from the breakdown of dead plant or animal parts.

Detritus - Litter formed from fragments of dead material in aquatic environments.

Dextral- right-handed, clockwise

Diadromous - migratory between fresh and salt waters

Diameter - In gastropods, the greatest width of the shell; in bivalves, a measure of shell convexity.

Diapause - period of arrested growth and development, often used to survive harsh environmental conditions.

Diatom- microscopic unicellular marine or freshwater colonial alga having cell walls impregnated with silica

Diatomaceous earth - siliceous geological deposits made up of diatom frustules

Dichotomous- (adj) Divided almost equally into two parts - often applied to a branching pattern.

Diel - daily.

Diffuse growth - generalized growth, not localized at apex or base

Digenea- a subclass consisting of parasitic flatworms

Digitation - Finger-like projection outwards from outer lip. Dilate: Widened, expanded.

Dilacerate- Broken, interrupted.

Dimorphism - Occurrence of two distinct morphological types in a single population; in sexual dimorphism, male and female forms are different.

Dimyarian - Denoting, in the bivalve mullusks, the characteristic of having two (anterior and posterior) adductor muscles.

Dioecious - (two houses) producing male and female gametes on different individuals or clones

Diplobacillus- (n) A rod-shaped bacterium occurring in pairs linked end to end.

Diplobiontic- (adj) Having two free-living phases in life history, one haploid, the other diploid.

Diploid - of a cell or organism having two sets of chromosomes or twice the haploid number

Disciform- (adj) Flat and rounded in shape; discoid, disk-shaped.

Distal- (adj) Situated away from the center of the body.

Diurnal - having a daily cycle or occurring every day

Dorsal - In gastropods, lying on the side of the shell opposite the aperture; in bivalves, lying on the surface or margin nearest the hinge; in chitons, lying on the body surface that bears the eight shell valves.

Dorsal Fin - The fin/fins of the midline of the back of the fish or marine mammal.

Dorsal line or sulcus - the colourless longitudinal line on the back of the shell connecting both ends.

Dorsal margin - In bivalves the hinge region.

Dorsoventral- (adj) Extending from the back to the belly.

Dorsoventrally compressed - Elongated and/or flattened; length much greater than height.

Dorsum - Top region of the fish.

Dichotomous - split into two parts

Dinokont - a dinoflagellate with an flagellum circling the middle and a flagella on the posterior end

Drainage- watershed; the land, rivers, etc draining into a water body.

Dreissenid- (adj, n) belonging to a family of small freshwater mussels, aquatic bivalve mollusks. They attach themselves to stones or to any other hard surface using filaments. For the Great Lakes, includes zebra and quagga mussels.

Drift line - A line of debris left by waves at the high-tide line.

Druse - a colony of mussels



Ear(s) - Small extension of dorsal region of bivalve shell, usually with a notch between it and main part of shell, as in Pectinidae. In scallops and file shells, triangular or oblong projections at the ends of the hinge line.

Echolocate - Locate and discriminate among objects by producing sounds and then hearing the echo.

Emergent Vegetation - Plants that are rooted in the water but with most of the plant growing above the surface of the water, such as cattails and wild rice.

Ecology - The study of the effect and relationship of environment on an organism.

Ecophenotypic variation - A non-hereditary modification of the animal due to environmental and other factors.

Ecotype - a genetically distinct geographic population within species (or among closely related), which is adapted to specific environmental conditions such as local selective pressure or physical isolation.

Ectocarpin - sex hormone produced by female gametes of Ectocarpus that causes male gametes to cluster near source of the hormone

Ectoparasite - any external parasitic organism

Ectoproct - sessile mossy aquatic animal having the anus of the polyp outside the crown of tentacles

Edema - swelling of tissues owing to the accumulation of abnormally large amounts of fluid in intercellular spaces.

Edentate - Without hinge teeth.

Edentulous - Lacking teeth.

Effluent - (n) Water mixed with waste matter.

Egg Bank - large number of diapausing eggs found in pond and lake sediments. Their presence is thought to ensure survival in temporary ponds or in permanent bodies of water to ensure the continuation of a population through periods of poor recruitment and help create conditions for the coexestence of competing species.

Egg capsule - A protective structure enclosing an individual egg or a cluster of eggs.

Elevated - Raised up; high in proportion to diameter.

Ellipsoid - (adj) Being the figure of revolution of an ellipse, an ellipsoid, when rotated around the major axis. 3 dimensional oval.

Elongate - Extended; considerably longer in one dimension than another.

Elytra - (n) The hardened fore-wings of beetles, serving as sheaths for the membranous hind-wings, which constitute the true organs of flight.

Emarginate - having a notched tip

Embryonic whorls - Whorls which have been formed prior to hatching.

Encapsulate - enclose in a capsule

Endemic - (adj) Native to, and restricted to, a particular geographical region. Highly endemic species are those with very restricted natural ranges; they are especially vulnerable to extinction if their natural habitat is eliminated or significantly disturbed.

Endocytic - living inside a cell

Endopod - mesial (inner) branch of an appendage.

Endotoxin - a toxin that is confined inside the microorganisms and is released only when the microorganisms are broken down or die

Endozoic - living with tissues of animal host

Entoprocts - any of various mosslike aquatic animals usually forming branching colonies; each polyp having a both mouth and anus within a closed ring of tentacles

Ephippia - resting egg

Epibenthic - found on the surface of the sediments

Epibiont - (n) Organism that lives attached to another organism but without benefit or detriment to the host.

Epicone - Anterior (front) part of a dinoflagellate, above the horizontal flagella.

Epiphyte - an organism that spends part or all of its life cycle growing on a plant

Eyespot - swelled area attached to a flagella that contains pigment. The pigment proteins respond to the presence of light and signal the flagella to move toward it.

Epidermis - (n) outer layer of cells in plants and animals

Epifauna - Animals that normally live exposed, above the substratum surface; may be with or without attachment.

Epilithic - (adj) Growing attached to an inorganic substratum, such as rocks, stones, etc.

Epiphyte - plant that derives moisture and nutrients from the air and rain; usually grows on another plant but not parasitic on it

Epitheca - Same as epicone; anterior (front) part of a dinoflagellate, above the horizontal flagella.

Equilateral - When beaks in bivalve are central. The anterior and posterior ends of each valve being of equal size.

Equivalve - When the two valves of a bivalve shell are of the same shape and size.

Erratic - (adj) Irregular, unsteady, random; prone to unexpected changes.

Establish - (v) Introduce and then settle.

Estuarine - (n) Of or having to do with the area where the sea meets a freshwater stream/river.

Estuary - 1. (n) The part of the wide lower course of a river where its current is met by the tides. 2 (n) An arm of the sea that extends inland to meet the mouth of a river.

Euphotic - (adj) Refers to the surface layer of the ocean that receives enough sunlight for photosynthesis.

Eurasia - region of eastern Europe and western Asia.

Euryhaline - An organism that is capable of living in a wide range of salinity concentrations.

Eurythermal - (adj) Tolerating a wide range of temperature.

Eutrophic - (adj.) Having waters rich in mineral and organic nutrients that promote a proliferation of plant life, especially algae, which reduces the dissolved oxygen content and often causes the extinction of other organisms. Used of a lake or pond.

Excentric - (adj) One-sided; having the normally central portion not in the true center.

Excentrically - (adv) off-center

Excretion - feces discharged from the body

Exhalent - (n) An organ, such as the siphon on a clam, which is used for exhalation.

Exopod - lateral (outer) branch of an appendage.

Exoskeleton - the exterior protective or supporting structure or shell of many animals (especially invertebrates) including bony or horny parts such as nails or scales or hoofs

Exotic - non-native

Expanded - With dimensions proportionately greater than those of preceding parts of the shell.

External ligament - That portion of the ligament visible when the valves of a bivalve are closed. See Ligament.

Extirpation - local extinction, removal of all of a type of organism from a specific geographic area

Exudate - (n) A substance gradually discharged or secreted across intact cellular membranes or cell walls and present in the intercellular spaces or on the exterior surfaces of the plant.



Facultative - exhibiting some ability or function under some environmental conditions but not under others

False branching - (n) In bacteriology, the appearance of branching produced when a cell is pushed out of the general line of growth and develops a new line of growth while the remaining cells continue to develop along the original line of growth.

Family - taxonomic classification, group of genera collectivelly showing relationship.

Fastidious - (1) neat, (2) with specific growth requirements

Fauna - Animal life of a perticular area or epoch; as opposed to Flora, for all plant life.

Feces - (n) Waste matter discharged from an organism's intestines.

Fertilized/Fertilization - The union of a female gamete (egg) with a male gamete (sperm).

Fibril - (n) A fine hair or fiber.

Fifth leg - in most species of copepods this pair of legs is modified or vestigial. In males of some groups the fifth legs are extensively modified for copulation; in females the fifth legs may be modified to protect the egg sac.

Filament - (n) A thread- or hair-like structure.

Filamentous - (adj) Like a thread; consisting of threads or filaments

Filiform - (adj) Thread-like.

Filter-feeder - (n) Any aquatic animal that obtains nourishment by filtering particles of food from the water in which it lives.

Fission - reproduction of some unicellular organisms by division of the cell into two more or less equal parts

Flagellated - (adj) Having a flagellum or resembling a lash or whip ; (v) whipped.

Flagellum (pl. flagella) - A long whip-like extension that many single-celled aquatic organisms use for locomotion.

Flank - Side.

Food Webs - Interacting food chains in an ecological community.

Fluctuate - 1. (v) To vary irregularly. 2. (v) To rise and fall in or as if in waves; undulate.

Foliaceous - Leaf-like, flattened, projecting like tiles.

Forage - wander and feed

Foreshore - The intertidal zone.

Fossil - Any hardened remains or traces of plant or animal life of some previous geological period, preserved in rock formations in the earth's crust.

Fountain growth - multiaxial growth usually of many filaments in which cell divisions occur

Fragment - small piece, usually broken off

Fragmentation - a means of reproduction in which small pieces can grow into an entire new organism.

Frass - mixture of feces and plant bits

Free-living - living independently of any symbiotic or parasitic relationship with a host species.

Freighter - ship carrying freight (cargo)

Fresh water - water containing less than 0.5% salts.

Frond - compound leaf

Fructification - 1. (n) Organs of fruiting (especially the reproductive parts of ferns and mosses 2. (n)The formation or development of a fruiting body.

Frustule - siliceous cell wall of a diatom

Fucoidan - water-soluble, sulfated polysaccharide in Phaeophycean cell wall

Fucosan vesicle - small, refractive particle or physode in cell of Phaeophycea, containing tannin-like compounds

Fultoportula - Hollow tubular process in the valve of centric diatoms, through which polysaccharides and other carbon-containing substances are extruded. (Plural: fultoportulae.)

Fulvous - Dark yellow.

Furca - the two furcal rami, sometimes called caudal rami.

Furunculosis - (n) a skin disease caused by the inflammation of hair follicles, thus resulting in the localized accumulation of pus and dead tissue.

Fusiform - tapering at each end

Fusion cell - cell produced by fertilization


Galactose - a simple sugar found in lactose

Gametangium - (n) Cell or organ in which gametes develop. (pl. gametangia)

Gamete - (n) Reproductive cell capable of uniting in fertilization with compatible cell to form zygote, such as sperm or egg.

Gametophyte - (n) The plant generation that produces the gametes and usually has a reduced chromosome number.

Gape - An opening in a bivalve shell which is unable to shut tightly.

Gaping - Incapable of closing completely.

Gastro vascular - functions in both digestion and the distribution of nutrients to all parts of the body

Gastrointestinal - of or relating to the stomach and intestines

Gastropod - a class of mollusks typically having a one-piece coiled shell and flattened muscular foot with a head bearing stalked eyes

Gastrovascular Cavity - (n) The site of digestion in a cnidarian. (literally gastro=stomach, vascular = blood vessels or circulation and cavity = opening)

Gelatinous - (adj) Rubbery, jelly-like.

Gemmate - Bud-like sculpture.

Geniculate - jointed to permit bending at a abrupt angle, distinctly elbowed.

Geniculum - flexible portion of the thallus, such as the non-calcified segments between calcified intergenicula of articulated corallines

Genital - (adj) Refers to the reproductive or sexual organs.

Genital double-somite - the body segment resulting from the fusion of the genital and first abdominal somites in females.

Genital somite - the somite bearing the genital apertures, the seventh thoracic somite.

Genome - the full DNA sequence of an organism

Genotoxic - (adj) Damaging to DNA; pertaining to agents known to damage DNA.

Genotype - (n) the genetic makeup of an individual; for a particular trait, you can't always tell the genotype by looking at the phenotype.

Genus - (n) Group of genetically related species possessing certain characters in common and easily separable from other groups of species. A taxonomic rank for closely related species which share a common phylogenetic origin.

Germ cell - reproductive cell

Germinate - (v) To start or cause to start a process of growth or development; sprout.

Gill - The breathing organ in a mollusk. A respiratory organ that extracts dissolved oxygen and salts from the water.

Gill arch - the U-shaped cartilaginous structure that supports the gill filament.

Gill chamber - In bivalves, the space between and around the gills.

Girdle - Side view of a diatom; the region between two valves.

Girdle - part of a diatom frustule between valves, also called cingulum

Girdle Band - (n) In diatoms, the rings or bands of silica encircling the valves where they overlap. Also called cingulum. (pl. cingula)

Gland cell - special, refractive cell in some red algae which may function in secretion or storage of compounds

Glandular - relating to or affecting or functioning as a gland

Gliding movement - movement of an organism when in contact with substratum

Globose - (adj) Globular or spherical in shape

Glochidium - bivalved larval stage of unionacean bivalves (Mollusca), generally parasitic on fish.

Glucose - (n) A member of the simple sugar carbohydrate group that is found in fruits and honey. Glucose is the most common free sugar that circulates in the blood of higher animals.

Gnathobase - the coxal endite of the mandible, bearing the toothed cutting edge distally.

Gonopore - the external opening of the reproductive system, the oviduct in the female and the vas deferens in the male.

Gram Staining - (n) Gram staining (or Gram's method) is an empirical method of differentiating bacterial species into two large groups (Gram-positive and Gram-negative) based on the chemical and physical properties of their cell walls.

Gram-negative negative - (adj) refers to bacteria that have a thick double cell wall that contains lipopolysaccharide or endotoxin; these bacteria lose a violet stain when rinsed.

Gram-positive - (adj) (of bacteria) being or relating to a bacterium that retains the violet stain used in Gram's method.

Granulated - (adj) Roughened as by small grains or granules.

Gravid - carrying eggs or young, pregnant

Growth line(s) - Impressed lines on the shell-surface due to growth-stages and rest periods.



Habitats - The places where plants and animals live.

Hair - colorless, elongate unicellular or multicellular structures

Halophilic - organisms that thrive in environments with very high concentrations of salt.

Haplobiontic - having single, free-living phase in its life history

Haploid - cell or organism having a single set of chromosomes

Haptera - multicellular structures that form holdfasts of kelps

Haptonema- (n) In haptophytes, a peg-like organelle attached near the flagella - unique to the group. Its function is unknown.

Head - in describing Lernaea, a morphological term loosely used for the rounded knob projecting from the anterior margin of the cephalothorax.

Hemimetabolous - Having/undergoing incomplete metamorphosis, showing a gradual change from molt to molt, changing gradually from the nymph to the adult.

Herbivore - An organism that consumes plant material.

Hemocyanin - respiratory proteins containing two copper atoms that reversibly bind a single oxygen molecule (O2).

Hemorrhage- (n) Heavy or uncontrollable bleeding.

Herbivore - consumes food from trophic level 1, i.e., plant food.

Herbivore- plant eater

Hermaphrodite - having both male and female reproductive organs, capable of forming male and female gametes on the same individual

Hermaphroditic- (adj) Of animal or plant; having both male and female reproductive organs.

Hermaphroditic - An animal or plant having both male and female reproductive organs.

Heterocysts- (n) Specialized nitrogen-fixing cells formed by some filamentous cyanobacteria.

Heterogamous - sexual reproduction where gametes are not identical in size or shape

Heterogeneity - an adjective used to describe an object or system consisting of multiple items having a large number of structural variations.

Heteromorphic - having life history phases morphologically different, having distinctly different gametophyte and sporophyte stages

Heterotrichous- (adj) In certain algae, a body that is divided into both ground-hugging and erect parts. Literally, with two types of trichomes.

Heterotroph- (n) An organism that obtains its food from other organisms, living or dead. Consumer.

Hinge line - In bivalves, the area along the upper margin where the two valves are hinged. See Hinge Plate.

Holarctic - refers to the habitats found throughout the northern continents of the world as a whole

Holdfast - (n) A root-like structure that anchors aquatic sessile organisms, such as seaweed, other sessile algae, stalked crinoids, colonial cnidarians, and sponges, to the substrate.

Holometabolous - Having/undergoing complete metamorphosis during development; the stages include egg, larva, pupa and adult.

Homeostatic - a system, either open or closed, that regulates its internal environment and tends to maintain a stable, constant condition.

Homeotype - A specimen which had been compared with the original type material and found to be identical.

Host - an organism that harbors or nourishes another organism.

HUC 6 (n) Six-digit Hydrologic Unit Code. Hydrologic Unit Codes are used for pinpointing the location of a body of water within the United States.

HUC 8 (n) Eight-digit Hydrologic Unit Code. Hydrologic Unit Codes are used for pinpointing the location of a body of water within the United States.

Humic - of or relating to or derived from humus

Hyaline - Thin and translucent or transparent

Hyaline membrane (plate) - a transparent, thin extension of an appendage segment.

Hybrid - The offspring produced through interbreeding of two biological species; since hybrids are not fertile they are unable to reproduce. (Hybrids are difficult to document in marine mollusks).

Hydrofuge- (adj) Of a structure, shedding water, as the hair on certain animals.

Hydroid- (n) A type of marine invertebrate (cnidarian) related to anemones, corals and jellyfish. They can often look like plants but they are in fact animals.

Hydrophyte- (n) Aquatic plant.

Hydrozoa - (n) simple and compound polyps and jellyfishes including stinging corals and Portuguese man of war; of the class Hydrozoa (singular: hydrozoan).

Hypolimnion- (n) Refers to the deepest, coldest, most dense layer of water in a stratified lake (layers of water differing in temperature and density).

Hypolithic - living on lower surface of rocks

Hyporheic - a region beneath and lateral to a stream bed, where there is mixing of shallow groundwater and surface water.

Hypotheca - Posterior (rear) part of a dinoflagellate, area below the horizontal flagella.

Hypotype - Specimen or specimens of a species or subspecies re-described and figured subsequently to the original description. The term is becoming obsolete.

Hypovalve - flattened or covex plate of diatom frustule opposite the epivalve

Hypoxia- (n) A condition or environment with very low oxygen levels.


Imbricate - overlapping or layered as scales or shingles

Immature - not mature, juvenile

Inconspicuous - not noticeable

Incremental lines - Faint concentric growth lines.

Incrustation - An irregular deposit on the shell surface.

Incurved - Term used to indicate that a structure curves in upon itself, as do the umbones of certain bivalves, or the spines or lamellae of certain bivalves and gastropods.

Indicator species - A species whose status provides information on the overall health of the ecosystem and of other species in that ecosystem. Indicator species reflect the quality and changes in environmental conditions as well as aspects of community composition.

Indigenous - native

Indo-Pacific - The faunal province comprising the shallow waters of the Indian and tropical western Pacific Oceans.

Inequivalve - In bivalves, having the two valves dissimilar in shape and size.

Infauna - Sessile and mobile animals that spend part or all of their lives buried beneath the substratum.

Infective - capable of causing infection

Inferior - below

Inhalant - (adj) inhaling or serving for inhalation; “an inhalant pore”

Inhalant siphon - A tube-like organ which facilitates the intake of water. Initial whorl: In gastropods, the first visible whorl at the apex.

Insemination - the introduction of semen into the genital tract of a female

Instar - (adj) the larval or nymph stage of an immature insect between successive molts.

Integument - an outer protective covering such as the skin of an animal or a cuticle or seed coat or rind or shell

Intensity - mean number of parasites per infected host.

Interbreeding - breed animals or plants using parents of different races and varieties

Intercalary- (adj) between the apex and base or between two other reference points such as nodes.

Intercostae (n) - space between costae

Intercoxal sclerite - the plate that connects the coxae of a pair of swimming legs; coupler.

Intermediate valve(s) - Any one of the valves between the head and tail valves of a chiton.

Internode - a segment of a stem between two nodes

Interspace(s) - The region between a pair of raised ribs, cords, ridges or other linear surface ornament.

Interstitial - microhabitat comprising space between particles of sand and gravel, associated with wet or submerged habitats.

Intertidal zone - (n) The area of beach between the high and low tide waterlines.

Intracellular- (adj) Located or occurring within a cell or cells; “intracellular fluid”.

Introgression - the movement of a gene (gene flow) from one species into the gene pool of another by backcrossing an interspecific hybrid with one of its parents.

Invertebrates- Animals lacking a backbone

Iridescence - Colors of the rainbow in shifting hues and patterns.

Isomorphic - morphologically similar, having similar looking gametophyte and sporophyte phases of life history

Isopod- (n) One group of small to medium-sized crustaceans found in marine, freshwater and terrestrial habitats and as parasites.

Iteroparous- multiple breeding


No words here



Keel - Carina or ridge. A prominent, sharply raised rib, generally marking an abrupt change of slope in the shell outline. See carina.

Kelp - member of brown algal order Laminariales

Kinetoplast - a disk-shaped mass of circular DNAs


Labiate - having lips or parts that resemble lips

Labrum - The upper lip of an arthropod.

Lacustrine - living near lakes

Lagoon - a body of shallow salt or brackish water separated from the deeper sea by a shallow or exposed sandbank, coral reef, or similar feature.

Lamella (lamellae) - gill filament

Lamellate - Covered with scales or thin plates.

Lamina - flattened leaf-like blade

Lampricide - a chemical which is designed to target the larvae of Lampreys in river systems before their recruitment as parasitic adults.

Lanceolate - Long and spearhead-shaped.

Lancoelate leaves - Leaves having a rounded base tapering towards a pointed tip.

Larva (pl. larvae) - The immature, wingless form of many insects that hatches from the egg. The larva then transforms into a pupa, and then metamorphoses into the adult form.

Larval shell - shell of a molluscan larva before it undergoes metamorphosis, usually set off by a change of sculpture.

Lateral - (adj) Situated at or extending to the side.

Lateral line - a sense organ used to detect movement and vibration in the surrounding water.

Lentic - (adj) Inhabiting still waters such as lakes, ponds or swamps

Lentic - standing-water environments (e.g., lakes, wetlands, temporary pools).

Lenticular - Having the shape of a double convex lens.

Lesion - (n) A wound or injury.

Lethargic - deficient in alertness or activity

Leucoplast - colorless, usually starch-containing plastid

Life Cycle - A life cycle is a period involving one generation of an organism through means of reproduction, whether through asexual reproduction or sexual reproduction.

Ligament area - In some bivalves, the area between the umbones containing the external ligament.

Limnetic zone - open-water, deeper areas of a lake or pond, away from the littoral zone.

Lipopolysaccharide - large molecules consisting of a lipid and a polysaccharide joined by a covalent bond.

Lirate - finely lined

Littoral - (adj) near the shore, intertidal

Littoral zone - area of a waterbody shallow enough for growth of rooted aquatic vegetation.

Locomotory - motive

Loculus - a small cavity or space within an organ or in a plant or animal

Lophophore - (n) Horseshoe-shaped feeding organ with filament appendages used to gather food.

Lorica - a hard protective sheath

Lotic - running-water environments (e.g., streams, springs).

Lysis - (n) The breaking open of a cell by the destruction of its wall or membrane (v. Lyse)


Macroalga - (n) Large alga that can be easily seen. E.g. kelp.

Macronucleus - large nucleus

Macrophytes - (n) Plants of lakes, streams and wetlands that are visible with the naked eye.

Macroscopic - Barely visible to the naked eye.

Macrothallus - large, conspicuous phase of organisms's life history

Malacology - The branch of zoology that deals with the mollusk, the animal within the shell.

Malacozoology - The study of living mollusks in relation to their animate and inanimate environment.

Malleated - Surface having a hammered appearance.

Mandibles - Paired, pincer-like hardened mouthparts (jaws) in arthropods, which are used to grasp, tear, and push food into the mouth.

Mantle (diatom) (n) - a surface of the valve.

Mantle cavity - The space between the mantle and the visceral mass.

Mantle scar - A broad area of attachment of the mantle edge in bivalves (e.g., sportella), too wide to be called a pallial line.

Manubrium - the bulla can be divided into two main parts, the handle or manubrium and the anchor. The two parts are not always clearly delimited. The manubrium connects the maxillary arms (via two ducts) with the anchor.

Margin - edge

Margin of opercle - Edge of the operculum or gill covering.

Marginal processes - projections from the edge of a cell or cell wall

Marl - a byproduct of photosynthesis formed when bicarbonate is used

Marsupium - Structures in invertebrates for enclosing or carrying eggs or young.

Mature - An individual that has reached the age for reproduction.

Maxilla - the fifth and last pair of cephalic appendages. Historically referred to as the second maxilla.

Maxilliped - the first pair of thoracic appendages, located on the last somite of the cephalosome. Uniramous and typically modified for feeding or grasping.

Maxillule - the fourth cephalic appendage. Historically referred to as the first maxilla.

Maximum - most, highest (plural maxima)

Medial - (adj) Dividing an animal into right and left halves.

Medulla - central tissue of thallus

Meiosis - nuclear division in which chromosome number is reduced from diploid to haploid, genetic segregation of chromosomes

Meristem - (n) A group or region of cells dividing rapidly and initiating growth.

Meristematic - (adj) Describing tissue in a distinct region of a plant that is actively, or potentially active, in the process of cell division

Meroplankton - organisms that spend part of their life cycle as plankton and part on the benthos

Mesentery - a double layer of peritoneum that attaches to the back wall of the abdominal cavity and supports the small intestines.

Mesial (mesal) - pertaining to the middle or in the direction of the middle.

Mesially - (adj) Of, in, near, or toward the middle.

Meso-eutrophic - (adj) A productive status between moderate productivity

Mesohaline - (adj) Describing intermediate levels of salinity between freshwater and seawater, about 15ppt (parts per thousand)

Mesohaline - Moderately brackish water with a salinity range of 5-18 ppt.

Mesokaryotic - having chromosomes that persist in condensed form at all times, the condition of the dinoflagellate nucleus

Mesoplax (Metaplax) - An accessory plate behind the umbones of some Pholadacea.

Mesothermal (mineralogy) (adj.) - Of a hydrothermal mineral deposit, formed at great depth at temperatures of 200-300°C.

Mesotrophic - (n) Lakes have moderate levels of nutrients and algae. Metabolic

Metamorphosis - (n) The marked and rapid transformation of a larva into an adult that occurs in some animals.

Metasoma - posterior part of the body

Metasomal wings - posterior lateral projections from the last somite of the metasome of some copepods.

Metasome - includes the somites of the copepod body anterior to the major body articulation. The metasome bears the second through fifth pairs of legs in calanoids, and the second through fourth pairs of legs in cyclopoids, harpacticoids, and poecilostomes.

Micron - (n) A unit of length. One Micron = 39 millionths of an inch = one-millionth of a meter.

Microphagous - Consuming microscopic food.

Microthallus - the tiny, inconspicuous stage of an organism's life history, alternating with the macrothallus stage

Microvilli - microscopic, finger-like projections

Mitochondria - an organelle containing enzymes responsible for producing energy

Mollusca (Mollusk) - Soft-bodied, highly developed animals without a backbone and with an exterior or interior shell.

Molluscivorous - eating mollusks

Molt / Molting - A process where crustaceans and insects shed their exoskeleton (external support). This is an important growth process, enabling the animal's body to expand.

Mono - one

Monoecious - (adj) having male and female reproductive organs in the same plant or animal. Literally ‘one house’.

Monogenea - a group of largely ectoparasitic members of the flatworm

Monosiphonous - made of a single siphon or tube

Monostromatic - blade composed of a single layer of cells

Monotypic - a genus having only one species

Moorland - (n) a type of habitat found in upland areas, characterized by low growing vegetation on acidic soils.

Morph - type

Morphological - (adj) Related to the observable shape or anatomy of an organism.

Motile - (adj) Capable of self-propelled movement

Mottled - (adj) having spots or patches of color.

Mouthparts - the group of appendages near the mouth which are involved in feeding, comprising the paired mandibles, maxillules, maxillas, and maxillipeds.

Mucilage - (n) A gelatinous substance, a glob of mucous

Mucilaginous - having the sticky properties of an adhesive

Multialxial - axis composed of multiple, longitudinal filaments, each derived from one apical cell

Multiseriate - (adj) Occurring in more than one series (row)

Murolith - heterococcolith with an elevated rim but without well developed shields

Mutant - an organism that has characteristics resulting from chromosomal alteration

Myxosporea - a class of microscopic parasites, belonging to the Myxozoa. They have a complex life cycle which comprises vegetative forms in two hosts, an aquatic invertebrate (generally an annelid) and an ectothermic vertebrate, usually a fish.



Nacre - (n) Mother-of-pearl: the iridescent internal layer of a mollusk shell.

Naididae - (n) The Naididae (formerly known as Tubificidae) are a family of clitellate oligochaete worms like the sludge worm, Tubifex tubifex. They are key components of the benthic communities of many freshwater and marine ecosystems.

Nanoplankton - plankton from 2 to 20 microns in diameter that would pass through the mesh of a normal plankton net

Nape - the back side of the neck

Native Transplant - native to a portion of the region but moved to a non-native area in the same region.

Naturalized - introduced from another region and persisting without cultivation

Nauplius - one of the 6 pre-copepodite stages of development (N1 through N6).

Necrosis - (n) The localized death of cells (as from infection or the interruption of blood supply).

Nekton (“Swimmers”) - The nekton includes all aquatic animals that actively swim in the water column, such as fish or squid. The nekton is one of three divisions of aquatic life; the others are the plankton (“drifters”) and the benthos (“bottom dwellers”).

Nemathecium - wart-like structure bearing reproductive parts

Nematocyst - complex ejectile organellee produced in a new dinoflagellate genera

Nematode - unsegmented worms with elongated rounded body pointed at both ends; mostly free-living but some are parasitic

Neonate - (n) A newborn.

Neotenic - attainment of functional sexual maturity in an animal otherwise immature, or the retention of some immature characters in adulthood.

Neotropica - The biogeographic region including tropical Mexico, Central America, South America, and the West Indies.

Neotype (Neoholotype) - A specimen selected to serve as the holotype provided that the holotype or paratypes can be proved to have been lost or destroyed.

Neritic - living in coastal ocean waters

Neurotoxin - any toxin that affects neural tissues

Neuston - organisms that live at the ocean-atmosphere interface

Niche - the relational position of an organism's species

Nitrogen - (n) Symbol: N; Atomic Number: 7; Atomic Mass: 14.00amu. Nitrogen is found as a gas in nature and it is classified as a non-metal. It makes up over 75 percent of the air surrounding the Earth.

Nitrogen-fixation - incorporation of atmospheric nitrogen as a nitrogen source in the cells of certain bacteria and Cyanobacteria

Nocturnal - active at night

Node - (n) site on an axis from which leaves or branches arise

Nominate - Subspecies (or subgenus) having the same name as the subdivided species (or genus) and the same type. (non-): Indicates homonyms.

Non - prefix meaning not

Non indigenous - (adj) Not originating where it is found. Not native to the area.

Non-encapsulated - (adj) Not enclosed in a capsule or other small container.

Non-motile - (adj)- not capable of movement

Nuclear whorl(s) - Small, and generally smooth and sculptureless whorls which have been formed within the egg and which constitute the apex of gastropod shells.

Nucleotide - the basic structural unit of nucleic acids

Nucleus - the central organelle in a cell which contains DNA

Nudibranch - (n) Sea slug: any of various marine gastropods of the suborder Nudibranchia having

Nutritive cell - specific cell of carpogonial branch with which carpogonium fuses after fertilization in some red algae of the order Cryptonemiales


Obligate - (adj) Restricted to a particular set of environmental conditions, without which an organism cannot survive.

Oblique - Slanting and inclined.

Oblong - (adj) having the shape of or resembling an ellipse

Obtuse - blunt or rounded at the end

Occluded - (adj) obscured, covered

Ocellus - simple eye consisting of a single, beadlike lens, occcurring singly or in small groups.

Oligochaete - (n) Any of various hermaphroditic aquatic and terrestrial annelid worms, of the class Oligochaeta, that have single bristles along the body.

Oligohaline - 1. (n) Organisms tolerant of only a moderate range of salinities. 2. (n) Brackish water with a salinity of 0.5 to 3.0 (or 5.0) parts per thousand from ocean-derived salts. 3. (n) Sea water having a salinity of 17 to 30 parts per thousand.

Oligosaprobic - (adj) Applied to a body of water in which organic matter is decomposing very slowly and in which the oxygen content is high.

Oligotrophic - nutrient-deficient

Omnivore - consumes both plant and animal food, from trophic levels 1 and above.

Oocyte -an egg cell; a female gametocyte or germ cell involved in reproduction

Oogamy - union of gametes in which a sperm fertilizes a relatively large, non-motile egg

Oogenesis - egg production

Oogonium - (n) The earliest recognizable form of the ovum, or egg; present only in the ovaries of fetuses. (plural: oogonia)

Opaque - Solid, not letting light through.

Operculum - lid or covering structure.

Operculum -a hard flap serving as a cover for (a) the gill slits in fishes or (b) the opening of the shell in certain gastropods when the body is retracted

Order - the taxonomic grouping between class and family

Organelle - specialized structure in a cell, like a plastid or nucleus

Organic matrix - (n) The organic fraction intimately bound to a skeletal structure. A framework or structure made of organic material.

Orthogyrate - In bivalves, having the beaks pointed toward each other.

Osmoregulation - (n) control of the water and electrolyte balance

Ostiole - opening in conceptacle or cystocarp through which spores or gametes can escape

Ostracod - tiny marine and freshwater crustaceans with a shrimp-like body enclosed in a bivalve shell

Ovary - Organ that produces eggs.

Overwinter - Survive the winter, hibernate.

Oviparous - Producing eggs that hatch sometime after leaving the body.

Ovoid - (adj) egg-shaped (applied to 3-dimensional forms).

Ovoviviparous - Producing eggs that hatch within the body or immediately afterwards.


P1 to P4 - first through fourth swimming legs.

P5 - fifth pair of swimming legs, typically vestigial or modified for use in copulation.

Pachyodont - Descriptive of bivalve shell with one heavy, blunt, and shapeless hinge tooth.

Palatable - tasty

Papilla - blunt, rounded, or nipple-shaped projection. Used to describe legs 5 of ergasilids, which consist of a single short segment and associated basal seta.

Paraphysis - a sterile hairlike structure among sporangia or gametangia, as those in the brown algal order Fucales

Parapodia - Fleshy paddle-like appendages on each segment of a polychaete’s body.

Parasite - An organism that lives on or within a body and takes its nourishment from the host without giving any benefit.

Parenchyma - tissue composed of living thin-walled cells of equal diameter that usually function in photosynthesis or storage

Parietal - Referring to the cell wall; in close proximity to the cell wall.

Parietal region - That part of the body wall just within and just without the aperture, and posterior to the columella.

Parthenogenesis - process in which an unfertilized egg develops into a new individual; common among insects and some other arthropods

Particulates - (n) Free suspended solids.

Parturition - the process of giving birth

Pathogen -(n) A disease-causing microorganism or agent.

Pebbled - Sculptured with small, irregular bumps.

Pectoral fins - Fins attached to the shoulder on the side of the body.

Pedigerous somite - a somite bearing one of leg pairs 1 through 5 (for swimming or copulation).

Peduncle - stalk bearing an inflorescence or solitary flower

Pelagic - (adj) Refers to fish and animals that live in the open sea, away from the bottom.

Pellicle - thin protective membrane in some protozoa

Penial - (adj) penile: of or relating to the penis; “penile erection”

Penis - (n) the external male genitalia.

Penultimate - next to last.

Perennial - (adj) Persisting for several years, sometimes dying back to a perennial crown during the winter and initiating new growth each spring.

Pereopod - walking legs

Perianth- The outer envelope of a flower.

Periostracum - (n) Thin coat of horn-like material found on mollusks.

Periphyton - (n) Microscopic plants or algae that are firmly attached to solid surfaces under water such as rocks, logs, pilings and other structures.

Peristome - region around the mouth in various invertebrates

Peristomium - (n) The area or parts around the mouth in certain invertebrates, such as the echinoderms.

Peritoneum - lining of the abdominal cavity

Perivalvar axis - (n) Axis alongside or in the vicinity of a valve.

Permeability - (n) A measure of the ease with which water penetrates a material.

Pervalvar - (adj) Alongside of or in the vicinity of a valve.

pH - (n) A measure of the acidity or alkalinity of a solution, numerically equal to 7 for neutral solutions, increasing with increasing alkalinity and decreasing with increasing acidity. The pH scale commonly in use ranges from 0 to 14.

Phagotrophy - endocytosis or engulfing particles of food as a mode of nutrition

Phenotypic - (adj) Of or relating to the observable characteristics of an individual.

Phosphorous - (adj) Symbol: P; Atomic Number: 15; Atomic Mass: 30.97amu. Phosphorus is a very reactive element and is classified as a non-metal. Plants and animals need phosphorus to survive. Phosphorus is often the limiting nutrient in freshwater systems.

Phosphorous Enrichment - (n) The adding of excessive phosphorous into a freshwater or marine ecosystem.

Photophilic - (adj) Light-loving. Refers to organisms that thrive in bright sunlight.

Phototactic - a behavioral response of an animal exposed to light, may be movement towards (positive) or away from (negative).

Phragmoplast - microfibrils parallel to the spindle axis at telophase across which a cell plate is deposited in cell division

Phycobilin - biliprotein pigments of Cyanobacteria and Rhodophyta

Phycoplast - assemblage of microtubules perpendicular to the spindle and at the equator of the cell at telophase in cell division

Phylogeny - The history of the evolution of a species.

Phylum - primary taxonomic grouping, division

Physodes - vesicles containing polyphenolic compounds (Naturally occurring compounds in grapes and wine, e.g. tannins), probably distasteful to most grazers.

Phytoplankton- A type of plant plankton, such as algae, that is the basic food source in many aquatic and marine ecosystems.

Phytotelm (pl. phytotelmata) - natural recesses of plants, such as leaf axils and treeholes, that collect water.

Pinnate - feather shaped, with lateral branches on either side of a central axis

Piscivore - fish eater

Planktivore - plankton eater

Plankton - drifting organisms. The plankton includes all aquatic organisms that are carried passively in the water currents.

Planktonic - (adj) Of or relating to plankton, a collection of small or microscopic organisms that float or drift in great numbers in fresh or salt water especially at or near the surface.

Plantigrade - an animal that walks with the entire sole of the foot touching the ground

Planula - worm-shaped ciliated larvae

Plasma membrane - a thin membrane (a double layer of lipids) enclosing the cytoplasm of a cell.

Plasmid - (n) A circular, self-replicating form of DNA found in many species of bacteria.

Plasticity - (n) malleability: the property of being physically malleable; the property of something that can be worked or hammered or shaped without breaking.

Plastid - (n) Any of several pigmented cytoplasmic organelles found in plant cells and other organisms, having various physiological functions, such as the synthesis and storage of food.

Plastron - (n) The nearly flat part of the shell structure of a tortoise or other animal, similar in composition to the carapace.

Platyhelminthes - flatworms

Pleistocene - from two million to 11 thousand years ago, extensive glaciation of the northern hemisphere

Plurilocular - having many small chambers or locules

Podocyst - a type of resting body, literally foot-cyst. Podocysts are cellular balls surrounded by a chitin-like membrane that protects the organism during cold temperatures or food-shortage.

Poikilothermic - animals having body temperature that varies with the environment

Polychaete - A bristle-worm.

Polyglucan granules - polymers of glucose somewhat like glycogen in animals

Polyhaline - Highly brackish water with a salinity of range 18-30 ppt.

Polymorphic - (adj) Literally ‘many forms’; Relating to the occurrence of more than one kind of individual (independent of sexual differences) in an interbreeding population; “a polymorphic species”.

Polyp - a small vascular growth on the surface of a mucous membrane

Polyphyletic - one whose members' last common ancestor is not a member of the group.

Polysiphonous - (adj) having many siphons; Referring to a construction characteristic especially of the Rhodomelaceae in which a simple ring of cells is produced, by longitudinal segmentation, around every cell of a primary uniseriate filament, the central or axial cell; or pericentral cells.

Polystichous - type of thallus constructed of true parenchyma as in some brown algal orders

Polystromatic - blade of many cell layers

Ponto-Caspian - areas stretching from the north of the Black Sea (called Pontus Euxinus in antiquity) as far as the east of the Caspian Sea, from central Ukraine across the Southern Federal District and the Volga Federal District of Russia to western Kazakhstan.

Pores - Small openings in the skin.

Postantennular spine - a spinous process associated with the antennae in Argulus.

Posterior - back, hind, rear

Posterior slope - Surface of valve of bivalve shell from umbo to posterior ventral margin.

Postero-dorsal surface - Dorsal surface of bivalve shell posterior to umbones

ppt - An abbreviation for parts per thousand and a measurement of salinity. For example, the open ocean is 35 parts per thousand (ppt). This means that if you had 1,000 buckets of sea water, and could put the salt and water in separate buckets, 35 of the buckets would be filled with nothing but salt.

Pre- - before

Prechlorination - (n) The addition of chlorine at the headworks of a treatment plant prior to other treatment processes.

Predator - An organism that captures or preys upon another organism for its food; a predaceous organism.

Prevalence - percentage of host fish infected by a particular parasite.

Proboscis - (n) The elongated mouthparts of some insects.

Process - Any object protruding from the surface of a cell.

Proctodeum - the most posterior portion of the alimentary canal.

Procumbent - trailing, lying flat along substratum, prostrate

Prodigious - (adj) exceeding: far beyond what is usual in magnitude or degree.

Prodissoconch - The embryonic shell in bivalves and scaphopods. See also Nucleus.

Produced - Prominently extended, elongated.

Profundal - deep bottom of a lake or sea

Propagule - (n) A structure with the capacity to give rise to a new organism, e.g. a seed, a spore, or a part of the vegetative body capable of independent growth if detached from the parent.

Propagule - multicellular structure for asexual reproduction

Prosome - the region of the body anterior to the major body articulation. The cephalosome together with the metasome form the prosome.

Prosomite - a somite of the prosome.

Prosternum - (n) The lower or ventral surface of the prothorax.

Prostomium - (n) Area in front of the mouth.

Prostrate - (adj) Being flat on the ground.

Proteinaceous - (adj) Relating to or of the nature of protein.

Prothorax - (n) the front part of an insect thorax which includes the attachment points for the front legs.

Protoplast - (n) A membrane-bound cell from which the outer wall has been partially or completely removed. The term often is applied to plant cells.

Protopod - the common basal part of an appendage, typically comprising the coxa and basis.

Protozoa - single-celled animals

Protrude - extend out or project in space

Protuberant - bulging outward

Proximal - situated nearest to point of attachment or origin

Pseudo - false

Pseudocardinal - (adj) false first

Pseudocardinal teeth - (n) Type of “teeth” found in clams.

Pseudocellus - (n) A false ocellus. A structure appearing similar to an ocellus but without visual capability.

Pseudofilament - false filament. Loose chain of individual cells held together by mucilage or attached at the end walls, rather than sharing a common cell wall as in a true filament

Pseudomembrane - (n) A tough, thick material on a mucosal or skin surface; a false membrane or covering.

Pseudonodulus - False nodulus or node, (diatom) a single structure that normally appears under the light microscope as a circular spot, usually hyaline but sometimes with faint markings; it is actually a hole in the shell - either funnel-shaped with a thickened rim or opening into a larger chamber.

Pseudoparenchyma - tissue resembling parenchyma with large, thin-walled cells, but developmentally filamentous

Pseudopod - temporary outgrowth used by some microorganisms as an organ of feeding or locomotion

Pseudoumbilicus - Depression or cavity in the base of the shell, involving only the body whorl, so that it is not a true umbilicus.

Puncta - (n) Pore or perforation through the valve, an areolae is a puncta bounded by an internal or external sieve membrane.

Pupa (pl. pupae)- The stage in holometabolous insects that occurs after the larval stage, during which the insect metamorphoses into the adult form.

Pupal - The transformational stage between larva and adult.

Pupate - (v) To go through a pupal stage; that is, to change from a larva to an adult, as in many insects.

Pupation - The tranformation between larva and adult.

Pycnocline - The pycnocline is the depth in the water column where there is an abrupt change in density, temperature, and salinity. A pycnocline often forms in the Chesapeake Bay and its tidal tributaries when the lighter, warmer, and fresher water coming downstream from the spring rains overlays the denser, colder, and saltier water of the salt wedge bringing water upstream from the ocean.

Pyloric caeca - (n) Blind sacs attached to the pyloric (stomach connecting intestine) section of the digestive tract.

Pyrenoid - (n) An organelle in or extending from the chloroplast and associated with reserve food accumulation.


Quadrangular - with 4 angles

Quadriflagellate - (adj) Having four flagella (cells).

Quiescence - (n) Quiet and inactive restfulness.



Ramus - a branch of an appendage, either the exopod or endopod.

Raptorial - living by preying on other animals especially by catching living prey

Receptacle - fertile area where gametangia or sporangia arise as in the brown algal order Fucales

Recommence - (v) Begin again.

Red Tide - (n) A reddish discoloration of coastal surface waters due to concentrations of certain toxin-producing algae.

Redox - (n) Redox, or reduction-oxidation, is a process in which an exchange of electrons occurs between two chemical elements.

Reduced - becoming smaller or lesser, smaller than normal

Reservoir - (n) An artificially created pond, lake or other space used for storage, regulation or control of water. May be permanent or temporary. 2. (n) a storage space.

Resorption - (n) The process of breaking down and assimilating something which was originally a distinct part of the body. With respect to bone, resorption refers to the breakdown of bone by osteoclasts that result in the release of calcium and phosphate (bone mineral) into the blood.

Respiratory - breathing

Resting cell - (n) A cell that is not actively in the process of dividing.

Resting stage - A point at which the molluscan shell is not being enlarged to accommodate growth, often marked by a thickening or ridge left on the shell surface.

Resuspension - a renewed suspension of insoluble particles after they have been precipitated.

Retention - 1. (n) That part of precipitation falling on a drainage area which does not escape as a stream flow, during a given period. 2. (v) The storage of stormwater to prevent it from leaving the development site. May be permanent or temporary. 3. (v) to retain or hold.

Reticulation - Pattern formed by obliquely intersecting threads or linear ridges of ornament.

Revolving - Turning with the whorls, or spirally.

Rhachis - A stemlike central gill axis supporting other elements.

Rheophilic - (adj) prefers to live in fast moving water.

Rhinophores - The posterior pair of tentacles on any opisthobranchs, especially nudibranchs.

Rhizoid - (n) A root-like structure forming part of the thallus in certain algae and fungi; it may anchor the organism to the substratum and/or act as an absorptive organ.

Rhizomes - A form of reproduction where a plant grows an underground offshoot from its roots or stems those surfaces and grows into a new plant at a different location.

Rhomboidal - With four more or less equal sides and no right-angled corners.

Riblet(s) - A small or narrow rib.

Ribosomes - an organelle in the cytoplasm of a living cell, they attach to mRNA and move down it one codon at a time and then stop until tRNA brings the required amino acid; when it reaches a stop codon it falls apart and releases the completed protein molecule for use by the cell

Ridge - Sharp-edged elevation of shell surface occurring as a single line.

Riffle - (n) A shallow area of a stream in which water flows rapidly over a rocky or gravelly stream bed.

Riverine - (adj) Relating to, formed by, or resembling a river.

Rod - (n) elongated sphere, Any rod-shaped bacterium.

Rostrate - Drawn out into a beaklike process.

Rostrum - a median extension, between the antennules, of the anterior margin of the dorsal cephalic shield.

Rotifers - (n) A phylum that includes organisms that have ciliated mouths and a retractable “foot” for anchoring. “Wheel-animals”

Rubble - A dense accumulation of broken shells, coral fragments, and stones on the sea bottom.

Rugose - wrinkled

Ruminant - any of various cud-chewing hoofed mammals having a stomach divided into four (occasionally three) compartments


Sagittal - (adj) Up and down, as opposed to transverse.

Salmonid - (n) A member of the family Salmonidae, which includes salmon, trout and whitefish.

Sargassum weed - A brown alga found on the open ocean, especially in the Atlantic.

SAV - Any Submerged Aquatic Vegetation, i.e., vascular aquatic plants that are rooted in the bottom sediments and grow no higher than the surface of the water, such as eelgrass or redhead grass.

Saxicolous - living on rock

Saxitoxin - neurotoxin produced by dinoflagellate Gonyaulax

Scavenger - An animal that feeds on refuse or dead and decaying animal and plant material.

Schizogony - asexual reproduction by multiple fission; characteristic of many sporozoan protozoans

Scientific Name - name agreed to by taxonomists internationally, usually the scientific name is given by the discoverer, but sometime organisms are renamed based on new knowledge of their genetic relationships to other organisms. Properly, the scientific name includes the genus name and species name, both in italics, e.g., humans are Homo sapiens.

Sculpture - A pattern of raised or depressed markings on the shell's surface. Synonymous with ornament, the term preferred here.

Scutes - modified scales that are spiny and keeled

Sediment - mud at the bottom of a lake or river.

Segment - in reference to the body, a “segment” is composed of 2 or more fused somites; alternatively, one of the sections of a jointed appendage.

Selenium - (n) Symbol:“Se” Atomic Number:“34“ Atomic Mass: 78.96amu. It is classified as a non-metal. Selenium is found in many forms. It may have red crystals or a grayish metal color.

Self-fertilization - fertilization by the union of male and female gametes from the same individual

Semelparous - reproducing once in a lifetime

Semiterrestrial - as applied to copepods, able to live in moist “terrestrial” environments such as humid soil and leaf litter.

Sensillum - epithelial sense organ.

Septicemia - (n) Disease caused by the spread of bacteria and their toxins in the bloodstream. Also called blood poisoning.

Serotonin - (n) A neurotransmitter that regulates many functions, including mood, appetite, and sensory perception.

Serration - (n) A row of notches; “the pliers had serrations to improve the grip”.

Sessile - permanently attached to a substrate; not free to move about

Sessile - Not free to move around; sedentary.

Seta - a tapering, moveable armature element, which is hollow and is inserted into a hole (socket) on the surface of the integument through which an associated muscle may be attached. Setae may be smooth or bear a variety of plumage.

Seta (pl. setae) - Hair-like bristles mostly used for locomotion.

Seta formula - the number of setae on the terminal segments of the exopodites of legs 1-4 respectively.

Setae - (n) Bristles or hairs.

Setal - (adj) A generic term for all the spine like structures (bristles, hairs, spines and trichobothria) that arise from the cuticle.

Setiferous - bearing one or more setae.

Setiform - formed like a seta, i.e. relatively thin and flexible, with or without fine hairs.

Setose - with many setae

Setule - a small, slender ornamentation element, which is borne on the surface of the integument.

Sexual reproduction - (n) Process in which two cells, termed gametes, come together to form one fertilized cell that contains genetic information from both parental cells.

Sheath - (n) an enveloping structure or covering enclosing an animal or plant organ or part.

Shelly - Composed of calcium carbonate rather than conchiolin; i.e., with a calcareous rather than a horny texture.

Shield - In gastropods, a thickened, distinctly margined callus on the body whorl near the inner lip.

Side teeth - In bivalves, hinge teeth on either side of the central teeth, at the ends of the hinge area.

Sieve area - field of pores through which translocation occurs as in brown algal order Laminariales

Sigmoidal Response - (adj) A classic response in which the relationship between the dependent and independent variables shows a characteristic S-shaped curve, indicating a transition from slow-to-rapid response followed by a plateau.

Silica - (n) A white or colorless crystalline compound, SiO2, occurring abundantly as quartz, sand, flint, agate, and many other minerals and used to manufacture a wide variety of materials, especially glass and concrete.

Siliceous - (adj) Relating to or containing or resembling silica; “gritrock is siliceous sandstone”.

Silicified - (adj) Combined or impregnated with silicon or silica, especially the latter; as, silicified wood.

Siphon - (n) a tubular organ in an aquatic animal (especially in mollusks) through which water can be taken in or expelled.

Siphonaceous (siphonous) - (adj) Relating to green algae that are tubular, multinucleate and not divided into cells by cross walls

Slope - One face of an angled bivalve shell, whether anterior, posterior, or central.

Snout - Fleshy part of the head before the eye and above the mouth.

Somite - a single, original body segment.

Sorus - a group or cluster of reproductive structures

Spawning - A form of sexual reproduction where microscopic eggs and sperm are discharged into the water column.

Spermatheca (n) - An organ of the female reproductive tract in insects, some mollusks, and certain other invertebrates and vertebrates. Its purpose is to receive and store sperm from the male, and it is usually the site of fertilization when the oocytes are ready.

Spermatogenesis - (n) The series of cell divisions in the testis by which maturation of the gametes (sperm) of the male takes place.

Spermatophore - packet of spermatozoa enclosed in a membranous capsule, which the male attaches with a glue on or near the female gonopore. In calanoids and harpacticoids the spermatophores are usually banana-shaped and attached singly; in cyclopoids they are usually bean-shaped and attached in pairs.

Spermatozoid - a motile male gamete of a plant such as an alga or fern or gymnosperm

Spine - a short stiff structure that is not inserted in a hole/socket passing through the integument; often loosely used for “spiniform seta.”

Spine formula - the number of spines on the external and apical edges of the last segment of the exopodite of the swimming legs, P1 to P4 respectively.

Spinule - a small spine.

Spiracles - (n) The breathing openings in the thorax and abdomen of insects.

Splash zone - (n) the water line ; The area where waves of ocean or lake strike the support members of offshore platforms and installations;.

Spleen - (n) A large dark-red oval organ on the left side of the body between the stomach and the diaphragm; produces cells involved in immune responses.

Sporadic - recurring in scattered and irregular or unpredictable instances

Sporangium - (n) A thick case containing one or more asexual spores. (Plural: Sporangia)

Spore - (n) Reproductive body, usually microscopic, that are produced by mushrooms, plants, bacteria, and Protozoa and that are widely dispersed.

Sporophyll - fertile, spore-producing blade as in brown algal order Laminariales

Stage - (n) A small platform on a microscope where the specimen is mounted for examination.

Statoblast - (n) An asexually produced encapsulated bud of a freshwater bryozoan that is released upon disintegration of the parent colony in autumn, remains inactive through winter, and develops into a new organism in spring.

Stellate - star-shaped

Stenothermic - (adj) a species or living organism only capable of living or surviving within a narrow temperature range.

Stephanokont - with ring of flagella

Stocked - (adj) Populating a body of water with fish reared in hatcheries.

Stolon - An above ground shoot or runner that results in a new plant.

Stomachal - (adj) relating to or involving the stomach

Stratification - (adj) The formation of separate layers (of temperature, plant, or animal life) in a lake or reservoir. Each layer has similar characteristics such as all water in the layer has the same temperature.

Stratum - (n) layer (plural: strata)

Striae - One or more rows of perforations.

Strutted processes - extensions of the cell or cell wall providing supports which hold the individual cells of the filament apart. E.g.,

Subaerial - (adj) Pertaining to land regions just above water level (ie, under air).

Subapical teeth - Teeth located just away from the apex (tip) of the mandible (in contrast to apical teeth, which are located on the tip of the mandible).

Subchela - the distal, moveable part of an appendage that opposes the unmodified flat surface of the proximal segment.

Subitaneous egg - develops and hatches with no arrest in development; usually produced during the warm season (summer eggs).

Sublittoral - below lowest low tide level

Subovate - (adj) Nearly in the form of an egg, or of the section of an egg, but having the inferior extremity broader; nearly ovate.

Sub-rhomboid - (adj) Somewhat diamond shaped.

Subspecies - A geographically defined group of populations comprising individuals which differ in certain characters from other such subdivisions of the species.

Substratum - (n) A layer that lies underneath another; The underlying cause or basis of something

Subtidal - The zone of the shoreline that is below low tide and is always covered by water.

Sulcations - (n) Channels or furrows.

Surfeit- eating until excessively full

Swim bladder - an air-filled sac near the spinal column in many fishes that helps maintain buoyancy

Swimming leg - one of the first through fourth pairs of legs, located on the third through sixth thoracic somites; these legs are relatively unmodified and are used primarily for movement.

Symbiosis - To live together; a condition in which two animals, two plants, or a plant and an animal live in partnership. The relationship can be that of commensalism, where one organism benefits from activities of the other; parasitism, where one organism lives on another to the detriment of its host; or mutualism, where both organisms benefit from the association.

Sympatric - occurring in the same or overlapping geographical areas

Syntype - One of several specimens collectivley designated type of a species.



Tangential - (adj) Tangent to a curve. In circular motion, used to mean tangent to the circle, perpendicular to the radial direction.

Taxon - (n) A term used to denote any group or rank in the classification of organisms, e.g., class, order, family. (pl. Taxa)

Taxonomy - a classification of organisms into groups based on similarities of structure or origin etc

Telangiectasis - an abnormal dilatation of capillary vessels and arterioles that often forms a tumor.

Teleost - bony fish

Temperature shock - (n) State of shock (abnormally fast gill rate, resting on the bottom, pale coloration) in fish (or other organisms) due to a sudden change in temperature. A temperature decrease causes more severe shock.

Tentacles - any of various elongated tactile or prehensile flexible organs that occur on the head or near the mouth in many animals; used for feeling or grasping or locomotion

Terminal - located at the distal end of an appendage.

Terminal cell - The last or end cell on a multicellular organism.

Terminal spots - A pair of spots at front or rear end of shell.

Terrestrial - Living or growing on land or in the soil.

Thallus - (n) The vegetative body of the lichen, composed of both fungus and alga. (pl. thalli)

Thermocline - (n) zone in water where the temperature changes drastically.

Thermophilic - an organism that thrives at relatively high temperatures, between 45 and 80 °C.

Thorax - a division of an animal's body that lies between the head and the abdomen.

Tidal - (adj) Involving the periodic variation in the surface level of the oceans and of bays, gulfs, inlets, and estuaries, caused by gravitational attraction of the moon and sun.

Tidal freshwater - Freshwater (0-0.5 ppt) that is tidally influenced.

Tidal system - (n) The systems involving the periodic variation in the surface level of the oceans and of bays, gulfs, inlets, and estuaries, caused by gravitational attraction of the moon and sun.

Toxicant - (n) poison: any substance that causes injury or illness or death of a living organism.

Trace Minerals - (n) Nutrients essential to the body but found in very small amounts. Trace minerals include iron zinc, selenium, fluoride, molybdenum, copper, and manganese.

Transition zone - intercalary meristem in region between stipe and blade where active cell division occurs in the brown algal order Laminariales

Translucent -Allowing light to pass through, but not transparent.

Transmission - (n) the act of sending through or across, infection: an incident in which an infectious disease is transmitted.

Transmittance - the fraction of radiant energy that passes through a substance.

Trapezoid - a quadrilateral with two parallel sides

Trematode - parasitic flatworms having external suckers for attaching to a host

Tropical - (adj) Refers to an area or climate that is frost-free and has temperatures high enough to support year-round plant growth if enough moisture is present.

Tufts - parallel, inter-twined filaments, usually perpendicular to the surface

Tumid - Swollen; enlarged.

Tunicate - primitive marine animal having a saclike unsegmented body and a urochord that is conspicuous in the larva.

Turion - A young or emerging shoot.

Tychoplanktonic - (adj) Refers to organisms that are circumstantially carried into the plankton. This can occur, for example, by turbulence.


Ulcer - a circumscribed inflammatory and often suppurating lesion on the skin or an internal mucous surface resulting in necrosis of tissue.

Ultrastructure - (n) Structure of an organism or cell at the electron microscopic level.

Unbranched - (adj.) Having no branches; straight-chain.

Undulate - (adj) With a wavy surface margin.

Unicellular - having only one cell

Unilocular - (adj) A term used to describe a radiographic appearance of a single, rounded compartment or locule that is well defined or outlined.

Unionid - refers to freshwater mussels in the order Unionoida. “Unio” is latin for pearls.

Uniseriate - (adj.) In one row.

Univalve - A mollusk consisting of a single spirally coiled shell.

Unpalatable - (adj) Displeasing to the taste.

Urosome - the region of the body posterior to the major body articulation.

Urosomite - a somite of the urosome.


Vacuole - a tiny cavity filled with fluid in the cytoplasm of a cell.

Variant - (n) Any unnamed variation within a species, variety, forma specialis or physiolgic race.

Veliger - (n) The planktonic larva of the zebra mussel.

Velum - (adj) A thin membrane, resembling a veil, such as: A locomotory and feeding organ provided with cilia found in the larval stage of bivalves.

Ventral - (adj) opposite of dorsal, front or stomach side

Ventral margin - In bivalve shells the edge or border which is directly opposite the hinge-line and beaks.

Ventral view - Base view.

Vermiform- worm-shaped.

Vertebrates - Animals with a backbone

Vertical mixing - (n) Up/down mixing in water, either via a vertical ocean current, by upwelling along a coast, by turnover (breakdown of thermal stratification) or by artificial means.

Vesicle - (n) A bubble or bladder-like structure. In algae.

Vestigial - (adj) Describing a characteristic which has receded from a useful structure in an ancestral form, and has little or no current use.

Virulent - (adj) Infectious; having the ability to cause disease

Viviparous - producing living young (not eggs).

Voracious - excessively greedy and grasping


Watershed - 1. (n) A ridge of high land dividing two areas that are drained by different river systems. Also called water parting. 2. (n) The region draining into a river, river system, or other body of water. 3. (n) A critical point that marks a division or a change of course; a turning point.

Weevil - any of several families of mostly small beetles that feed on plants and plant products; especially snout beetles and seed beetles

Weir - a fence or wattle built across a stream to catch or retain fish.

Whorl - (n) A ring of 3-more similar structures radiating from a common point.



Young-of-the-year - juveniles during the period from the last larval stage to adulthood, or one year of age, whichever comes sooner.


Zooid - one of the distinct individuals forming a colonial animal such as a bryozoan or hydrozoan.

Zooplankton - (n) The small animals that drift in the surface waters.

Zoospore - (n) any swimming spore, (e.g., found in algae and fungi). Zoospores can be haploid or diploid

Zygote - the product of fertilization

Zygotic meiosis - meiosis that occurs during zygote maturation or germination