Order Cladocera - Waterfleas

About 70 species of waterfleas make their homes in the waters of the Great Lakes basin. Of these, only a handful make up the bulk of the open water biomass. Leptodora kindtii is a native predatory waterflea. Two recent invaders, Cercopagis pengoi and Bythotrephes cederostroemi are also common predatory cladocerans. Larger members of the Daphnia family are most common in the spring: Daphnia retrocurva nearshore, Daphnia galeata in the deep clear waters, and Ceriodaphnia sp. in the warm upper waters. Smaller waterfleas in the families Bosminidae and Chydoridae become more abundant in the summer and fall: Bosmina in the cool, well-oxygenated waters, Eubosmina in warm epilimnetic waters and Chydorus in the eutrophic and near-benthic waters.

The Great Lakes have 4 species of predatory waterfleas, the natives Leptodora kintii and Polyphemus pediculus, and two exotics - Cercopagis pengoi and Bythotrephes cederstroemi. These are raptorial predators which grasp protozoans, rotifers, and small zooplankton with their forelegs. All other native Great Lakes waterfleas are herbivores, feeding on phytoplankton, attached vegetation or decaying organic material. Most use their legs to generate a current, filter appropriate sized food particles, and pass them to the mouth. The Chydoridae and Macrothricidae have modifications to their legs which enable them to cling to vegetation and/or detritus and scrape food particles from the surfaces.

Most cladocerans can reproduce by parthenogenesis (asexual reproduction), females producing 2-20 eggs per brood that develop into young without fertilization by males. As a result, males are not present in the population for much of the year. As long as environmental conditions remain favourable females will continue to reproduce in this manner, producing only female offspring. Eggs are laid inside a brood chamber along the back of the animal and are released as free-swimming juveniles when the parent molts. If the environment starts to deteriorate due to overcrowding, lack of food, oxygen depletion. or simply seasonal changes, eggs are produced that develop into males and females capable of sexual reproduction. These females produce eggs that once fertilized by the males are capable of surviving extended periods of harsh conditions such as drying or freezing (sometimes called resting stages). Each female produces only 1-2 such eggs in a specialized brood chamber called the ephippia. When the female molts, ephippia are released - eggs remain in the ephippia until conditions trigger hatching. In this manner cladoceran populations survive through winter and periods of drought. Some zooplankton resting stages are believed to have survived centuries buried in sediment. When environmental conditions are again favourable the eggs hatch and produce parthenogenic females.

Cladocerans have hard exoskeletons and molt many times as they grow. Many species show changes in shape as they grow - characteristic of age, season, or environmental conditions.

Order Profiles and General Information -

- "Zooplankton of the Great Lakes" by Balcer, Korda and Dodson. 1984.
The Cladoceran Body Plan
A Key to Cladocerans (Crustacea) of British Columbia (includes most Great Lakes families except Cercopagidae)
An Image-Based Key To The Zooplankton Of The Northeast (USA)
The Cladoceran Life Cycle
The Waterflea - An introduction to the taxonomy of the sub-fossil remains ot the Cladocera
Waterfleas - Jan Parmentier & Wim van Egmond
Cladocerans of the Thompson-Okanagan Region
MN Sea Grant - Seiche Article - Our Lake Has Fleas

Distribution and Habitat (access gallery by location)

Taxonomic Key (access gallery by taxa)

Browse Gallery

Distribution and Habitat x=present Image Link Scientific Name Lake Superior Lake Michigan Lake Huron Lake Erie Lake Ontario Habitat Family Leptodoridae             Leptodora kindtii x x x x x littoral and limnetic Family Polyphemoidea             Polyphemus pediculus x x x   x nearshore areas occassionally to 40m Family Cercopagidae             Cercopagis pengoi   x   x x   Bythotrephes longiramus x x x x x   Family Sididae               Diaphanosoma spp.             Diaphanosoma brachyurum x x x x   littoral Diaphanosoma birgei x x x x x sheltered open waters at depths of 3-6 meters Latona setifera x x x x   rare Latonopsis occidentalis       x     Sida crystallina x x x x x extremely patchy distribution Family Holopedidae             Holopedium gibberum x x x x x littoral and pelagic, prefers cold waters Family Daphnidae               Ceriodaphnia spp.           littoral and limnetic, usually nearshore or in the warmer upper layers of water Ceriodaphnia lacustris x x x x x   Ceriodaphnia laticaudata       x     Ceriodaphnia pulchella x     x   Ceriodaphnia quadrangula   x x x   Ceriodaphnia reticulata       x     Daphnia spp. x x x x x   Daphnia ambigua   x x x   very low abundances post-1970 Daphnia galeata x x x x x Deep, transparent waters. Daphnia longiremis   x x x x Usually found below the thermocline but above the poorly oxygenated regions Daphnia lumholtzi           Exotic. Daphnia parvula   x       Green Bay and Milwaukee Harbor - rare Daphnia pulex x x x x x easily confused with Daphnia retrocurva so ID uncertain Daphnia retrocurva x x x x x One of the most abundant cladocerans in the Great Lakes. Daphnia schodleri   x       Collected in 1970's   Scapholeberis spp.               Scapholeberis aurita   x   x   Occassional, near surface, littoral. Scapholeberis kingi x x   x   aka S. mucronata   Simocephalus spp.             Simocephalus exspinosus x           Simocephalus serrulatus   x   x   Abundant in the littoral areas of Lake Erie. Simocephalus vetulus x     x   Family Moinidae             Moina micrura x x       generally low numbers but may reach high densities in Green Bay Family Bosminidae               Bosmina coregoni x             Bosmina liederi x           Bosmina longirostris x x x x x Found in cool, well-oxygenated waters and littoral areas. Abundant during the summer.   Eubosmina spp.             Eubosmina coregoni x x x x x prefers warm, epilimnetic water. Abundant summer species, only recently observed in the Great Lakes (post-1970).   Eubosmina longispina (?)     x x x   Family Macrothricidae             Acantholeberis curvirostris     x     shallow waters of Georgian Bay, 1903   Drepanothrix dentata x x       rare - Isle Royale and Georgian Bay   Ilyocryptus spp.               Ilyocryptus acutifrons   x       SE Lake Michigan 1980 Ilyocryptus sordidus x x   x   littoral - rare Ilyocryptus spinifer x     x x variable abundance   Macrothrix laticornis x x   x x rare   Ophryoxus gracilis   x x     littoral Georgian Bay and Green Bay   Wlassicsia kinistinensis   x       occassionally found among nearshore vegetation Family Chydoridae             Acroperus harpae x x   x   littoral, benthic, abundant in some areas of Green Bay   Alona spp. x           Alona affinis x x x x x benthic, near bottom in weedy littoral areas, Alona circumfimbriata   x       littoral, benthic   Alona costata x x   x   low density, littoral, benthic Alona guttata x x   x   low density, littoral, benthic   Alona lepida x         planktonic, ID uncertain Alona quadrangularis   x   x   littoral, benthic   Alona rectangula x x   x   low density, littoral, benthic   Alonella spp.               Alonella excisa       x   rare   Alonella nana x     x   Isle Royale and littoral Lake Erie   Alonopsis elongata x         rare   Anchistropus emaginatus x             Anchistropus minor x x x     Isle Royale, Georgian Bay, Green Bay, weed-associated   Camptocercus spp.               Camptocercus macrurus       x   near bottom in weedy areas Camptocercus rectirostris x x x x x littoral, occassional high local abundances   Chydorus spp. x         Nearshore and littoral - eutrophic, usually found clinging to fliamentous algae. Epibenthic by day.   Chydorus faviformis   x         Chydorus gibbus x     x     Chydorus globosus x   x x     Chydorus latus       x   Chydorus sphaericus x x x x x   Disparalona spp.               Disparalona acutirostris x           Disparalona rostrata x x       recent (1980) and rare to Lake Michigan   Eurycercus lamellatus x x x x x benthic, moving into the water column at night Graptoleberis testudinaria   x x x   very low numbers Kurzia latissima     x x   occassional Leydigia acanthocercoides       x   5 sites, 1960 Leydigia leydigi   x x x   rare   Leydigia quadrangularis x           Monospilus dispar x   x x   <6 per cubic meter   Pleuroxus spp.               Pleuroxus aduncus       x   Cedar Bay Pleuroxus denticulatus   x   x   littoral   Pleuroxus hastatus x         open water 1893   Pleuroxus procurvus   x   x       Pleuroxus striatus       x   4 nearshore locations   Rhynchotalona falcata x         <1 per cubic meter Table drawn from "Zooplankton of the Great Lakes: A Guide to the Identification and Ecology of the Common Crustacean Species" by Mary Balcer, Nancy Korda and Stanley Dodson. University of Wisconsin Press. 1984. with additions from: Lake Superior: an invasion coldspot? 2003. Igor A. Grigorovich, Alexei V. Korniushin, Derek K. Gray, Ian C. Duggan, Robert I. Colautti& Hugh J. MacIsaac. Hydrobiologia 499: 191-210.

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