Order Eucopepoda - Oarsmen

More than 33 species of copepods call the Great Lakes home, however, in most of the open water regions of the Great Lakes only one or two species of calanoids and a single cyclopoid generally dominate. A greater variety of species are typically found in the littoral and benthic habitats, with harpacticoids being more common than cyclopoids in these areas.

Some copepods are strong swimmers. Vertical migration (daily movements up and down in the water column in response to food abundance, predators or other environmental cues) is common, particularly for the calanoids.

Copepods reproduce sexually, with females able to store sperm internally for later release with eggs. Eggs are usually brooded by the female in a sac or sacs attached to the genital segment (joining body and tail). Several clutches may be fertilized from a single mating. Copepod eggs hatch into small active larvae known as nauplii. Copepod nauplii molt as they grow, though six naupliar stages, each larger, more elongated and with more legs than the previous stage. The naupliar stages are followed by juvenile copepodid stages in which the young resemble adults but may lack some of the swimming legs. Juveniles continue to mature and molt until the sexually active adult stage is reached. Some species mature rapidly and can produce several generations per year, others require up to a full year to mature to the adult form.

Copepods are able to survive unfavorable conditions (e.g., winter) by entering diapause, a resting state similar to hibernation. Copepods in diapause are usually found on the lake bottom.

See:

Free-living and Parasitic Copepods (Including Branchiurans) of the Laurentian Great Lakes - USGS/Great Lakes Science Center

This includes taxonomic keys to group and species, profiles, photos of all species, distribution, life histories, ecology, and pretty much anything else you could possibly want!

See Also:
Profile - Museum of Victoria
Biology of Copepods - University Oldenburg
Introduction to Copepods - The Copepod Web Portal
Line drawings of nauplii, copepodid and adult copepods
Annotated Checklist of the Free-Living Copepods of the Great Lakes - JGLR
Identification of Nauplii N1-N6 and Copepodids CI-CVI of the Great Lakes Calanoid and Cyclopoid Copepods by
Czaika, Sharon C. - JGLR
Copepod Neuroecology - University of Hawaii
Tumor-like abnormalities in Great Lakes Copepods

Suborder Calanoida

Filter feeders which may have some ability to selectively filter certain sizes and types of algae. A few may be able to eat smaller zooplankton. Eggs are released to sink or held in a single egg sac. Calanoid copepods have been reported to be a food source for cyclopoid copepods, for chironomid insect larvae, Chaoborus sp. and for juvenile fish.

Free-living and Parasitic Copepods (Including Branchiurans) of the Laurentian Great Lakes - USGS/Great Lakes Science Center
Annotated Checklist of the Free-Living Copepods of the Great Lakes - JGLR
Zooplankton of the Great Lakes Central Michigan University - Profiles and photos for Eurytemora affinis and Limnocalanus macrurus.
An Introduction and Key to the Freshwater Calanoid Copepods of British Columbia
- Annotated line drawings
Southwest Missouri State University Zooplankton Project - Photos of Eurytemora affinis, Skistodiaptomus pallidus and Skistodiaptomus reighardi

Suborder Cyclopoida

Raptorial feeders with mouthparts modified for grasping and chewing. May be herbivores, omnivores or carnivores with distinct food preferences. Two egg sacs.

Free-living and Parasitic Copepods (Including Branchiurans) of the Laurentian Great Lakes - USGS/Great Lakes Science Center
Annotated Checklist of the Free-Living Copepods of the Great Lakes - JGLR
Southwest Missouri State University Zooplankton Project - Photos of Mesocyclops edax and Tropocyclops prasinus mexicanus
BioImages: The Virtual Field Guide (UK) - Photos of Acanthocylops vernalis, Eucyclops agilis and Tropocyclops prasinus mexicanus
- Line drawings of adult male and female (a-b)
- Animated gif of 'hopping' male - Research Strickler Lab

Suborder Harpacticoida

Great Lakes harpacticoid copepods have not been well studied. Predominantly benthic feeding on detritus. Two egg sacs.

Free-living and Parasitic Copepods (Including Branchiurans) of the Laurentian Great Lakes - USGS/Great Lakes Science Center
Annotated Checklist of the Free-Living Copepods of the Great Lakes - JGLR
Scientific Abstract - Invading Species Dominate the Harpacticoid Fauna in Nearshore Sands of Southern Lake Michigan. T.G.Horvath, E.J.Oberdick, L.L.Last, and R.L.Whitman. U.S. Geological Survey.

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