Field Guide

Aquatic Invertebrates

Showing 1 - 10 of 19 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 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 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.
Red midge fly larva, side view, in a petri dish
Midge Fly Larvae
Nearly 1,100 species in North America
Midge larvae look something like thin aquatic inchworms. They can be clear, whitish, olive, tan, or bright red. They occur in a variety of aquatic habitats. As adults, they resemble mosquitoes but they never bite.
Photo of a spotted fishing spider perched on the water's surface amid floating duckweed plants
Aquatic Spiders
Dolomedes spp., Tetragnatha spp., and others
A variety of spiders are adapted for live on and around water. Many of these are called fishing spiders. Several have the ability to run across the water’s surface. Some build webs, others do not.
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.
Photo of a northern, also called virile, crayfish.
Virile Crayfish (Northern Crayfish)
Faxonius virilis (formerly Oronectes virilis)
The virile crayfish is large, reddish brown or green, and lacks prominent markings. The pincers are green with orange tips and are studded with whitish knobs. Paired dark blotches run along the abdomen. This species is widespread.
Photo of a water nymph crayfish, side view of specimen carefully arranged against black background
Water Nymph Crayfish
Faxonius nais (formerly Orconectes nais)
The water nymph crayfish is normally found in streams but can also be found in a variety of other aquatic habitats. It is greenish brown or brown with no prominent markings. Its known distribution in Missouri is spotty.
lilliput
Lilliput
Toxolasma parvus
These diminutive mollusks are the smallest of Missouri’s freshwater mussels.
pink papershell
Pink Papershell
Potamilus ohiensis
This species enjoys the same geographic distribution in our state as the pink heelsplitter, and it generally resembles that species, too. But as the name suggests, the pink papershell usually has a thinner shell and is smaller. Also, it prefers rather shallow water with a good current.
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.