Overview of Freshwater Invertebrates of North America

• 10,000-15,000 species in temperate North America

• all major invertebrate phyla accept Echinodermata have freshwater representatives

Protozoa• ubiquitous

• important consumers of bacteria & cyanobacteria, algae, and other protozoans

• prey for oligochaetes, chironomids, rotifers, etc.

• do not tolerate anoxic conditions

Porifera • 25 species freshwater sponges in North

America

• one family (Spongillidae)

• symbiotic algae

• Gemmules

• restricted to waters containing silica

Cnidaria • Hydrozoa only; 20 species

• e.g. taxa:• Hydra (polyp)• Chlorohydra (polyp); contains Chlorella an

endosymbiotic algae• Craspedacusta (medusoid)

Platyhelminthes• class Turbellaria (Planarians)

• > 200 species

• mostly benthic scavengers

Rotifera “wheel animals”• 2500 species described

• free living herbivores & predators

• Corona

• muscular pharynx & mastix

Mollusca• class Gastropoda (350 species);

snails & limpets

• class Bivalvia (250 species); clams & mussels

Annelida• classes Oligochaeta & Hirudinea

Arthropoda• subphylum Chelicerata

• class Acari (water mites)

• subphylum Uniramia• class Insecta- 10 orders have aquatic

representatives

Arthropoda• subphylum Crustacea

• class Malacostraca- crayfish & shrimps, isopods, & amphipods

• class Ostracoda- "seed shrimps“

• class Brachiopoda- fairy shrimps, tadpole shrimps & cladocerans (e.g. Daphnia)

• class Copapoda- important zooplanktors

Order Hemiptera• “true bugs”

• piercing-sucking mouth parts

Order Diptera• flies, gnats, and

mosquitoes

• complete metamorphosis

• important disease vectors

Order Odonata- dragonflies & damselflies

• ~650 North American species

• aquatic nymphs; mostly fresh water

• flying adults

• common families:• Gomphidae• Aeshnidae• Corduliidae

Anisoptera vs. Zygoptera

Ephemeroptera- mayflies• rocky-bottom 2nd &

3rd order streams

• most with three caudal filaments

Order Trichoptera- caddis flies

• nymphs construct nets and cases

• cool lotic waters

Order Plecoptera- stone flies• inhabitants of

clean, cool water

• good bioindicators

• adults live 1-4 weeks

Order Megaloptera- dobson flies• also called

hellgrammites

• predaceous larvae

• common families:• Corydalidae• Sialidae

Chelicerata (water mites)

Order Isopoda• pill bugs, sow bugs

• aquatic and terrestrial forms

• dorsoventrally flattened body