Field Guide

Aquatic Invertebrates

Showing 1 - 10 of 16 results
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.
Photo of pulmonate snail crawling on rock
Lunged Aquatic Snails (Pulmonate Pond Snails)
Over 30 Missouri species in former subclass Pulmonata
Pulmonate, or lunged snails breathe via a lunglike pulmonary cavity, and they lack the hard trapdoor-like operculum found in gilled snails. Except for in the Ozarks, pulmonate snails predominate in most of the aquatic regions in our state.
Photo of a ramshorn snail on a wet rock.
Ramshorn Snails
Gyraulus, Helisoma, Menetus, Micromenetus, Planorbula spp.
Ramshorn snails are easy to identify at a glance, because the shell is a flat, disklike coil. Like other pulmonate aquatic snails, they lack the hard horny “trapdoor” possessed by other types of aquatic snails.
Hydras
Various species in the genus Hydra
We’ve all seen aquariums and pictures of tropical saltwater invertebrates such as corals, jellyfish and anemones—but did you know that there are similar creatures living in the freshwater habitats of Missouri?
Gray, speckled, translucent gelatinous blob cut in half to show structure
Bryozoans (Moss Animals)
Freshwater species in the phylum Bryozoa
Bryozoans are tiny, filter-feeding invertebrates. They create colonies that can be mossy, branching, or round and jellylike.
Photo of crane fly larva
Crane Fly Larvae
There are over 500 species of crane flies in North America.
Crane fly larvae are tan or gray grubs that live in aquatic habitats or in moist places on the ground. The harmless adults resemble huge mosquitoes.
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 a stonefly naiad clinging to a rock underwater
Stonefly Larvae
There are hundreds of species in North America
Stonefly larvae are aquatic and somewhat resemble the larvae of mayflies and damselflies. Their presence usually indicates good water quality.
See Also

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.