Field Guide

Aquatic Invertebrates

Showing 1 - 10 of 16 results
Photo of a spothanded crayfish viewed from above on white background.
Crayfishes
About 38 species in Missouri
Crayfish are freshwater aquatic invertebrates that look a lot like small lobsters, to which they are related. There are about 38 species of crayfish in Missouri.
Photo of a fishfly larva crawling among rocks in an aquarium.
Fishfly Larvae
Chauliodes, Neohermes, and Nigronia spp. (in eastern US)
Fishfly larvae look a lot like their cousins the hellgrammites, but they lack cottony or hairy gill tufts along the abdomen, and they have 2 short, fleshy tails at the hind tip.
Photo of an alderfly larva among rocks and gravel in an aquarium.
Alderfly Larvae
Sialis spp.
Alderfly larvae look a lot like their cousins the fishflies, but instead of having pairs of fleshy tails, they have only a single tail pointing straight back.
Photo of caddisfly larva with case made of detritus
Caddisfly Larvae
About 1,500 species in North America north of Mexico
The aquatic larvae of caddisflies are famous for building portable, protective cases out of local materials, including grains of sand, bits of leaves and twigs, and other debris. The adults are mothlike.
Photo of an aquatic tubificid worm among rocks in an aquarium.
Tubificid Worms (Tubifex Worms)
Tubifex spp. and other aquatic tubificid annelids
Tubificid worms, as a group, include the tubifex worms that aquarists feed to their pet fish. These segmented worms are related to earthworms and like them are detritus eaters.
Photo of a pink planarian on a rock.
Turbellarians (Planarians; Free-Living Flatworms)
Dugesia, Planaria, and other genera
Unlike their parasitic cousins in the flatworm group, turbellarians, or planarians, are tiny carnivores or detritus-eaters that glide smoothly across submerged leaves and other objects.
Water springtails congregate in water above soggy dead leaves
Water Springtail
Podura aquatica
In early spring, clusters of water springtails float on the surface of quiet waters, on muddy banks, and on protruding objects. Adults are bluish gray with reddish appendages.
Photo of amphipod on a rock
Scuds and Sideswimmers (Amphipods)
Species in the crustacean order Amphipoda
Often overlooked by people, but eagerly sought by fish, Missouri’s amphipods resemble shrimplike sowbugs. Scuds live in various aquatic habitats, and several species inhabit caves.
pond mussel
Freshwater Mussels
Bivalve molluscs in order Unionoida
Secretive and seldom seen, freshwater mussels are extraordinarily diverse in Missouri. We have nearly 70 species within our borders. Many are declining, and several are endangered.
Photo of several prosobranch pond snails crawling on a rock.
Gilled Aquatic Snails (Prosobranch Pond Snails)
Over 20 Missouri species in former subclass Prosobranchia
Gilled snails are one of two main groups of aquatic snails in Missouri (the other group is the "lunged" snails). Gilled snails, or prosobranchs, breathe with gills and possess a hard trapdoor-like operculum. They are most common in the Ozarks.
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About Aquatic Invertebrates in Missouri

Missouri's streams, lakes, and other aquatic habitats hold thousands of kinds of invertebrates — worms, freshwater mussels, snails, crayfish, insects, and other animals without backbones. These creatures are vital links in the aquatic food chain, and their presence and numbers tell us a lot about water quality.