Field Guide

Aquatic Invertebrates

Showing 1 - 10 of 45 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 hellgrammite
Hellgrammite
Corydalus cornutus
Hellgrammites are the aquatic larval form of eastern dobsonflies. They are fiercely predaceous and look a little like centipedes. Anglers often use them as bait.
Photo of a horsehair worm in an aquarium
Horsehair Worms
About 350 species scientifically described.
Adult horsehair worms can be nearly 3 feet long and live in water. They are practically featureless, smooth, aquatic worms that writhe into knots and curls.
Photo of a water scorpion, genus Ranatra, captured in a jar of pond water.
Water Scorpions
Ranatra spp. and Nepa apiculata
Water scorpions remain still, looking like a random bit of plant material. Then they suddenly grab their prey and deliver disabling fluids with a quick jab of their knifelike beak.
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 gray-speckled crayfish.
Gray-Speckled Crayfish
Faxonius palmeri (formerly Orconectes palmeri)
The gray-speckled crayfish is gray with numerous greenish-black speckles and blotches. A pair of large blotches are present near the back of the head, and another pair occur where the carapace joins the abdomen. In Missouri, it is found only in the southeastern section.
Photo of a painted devil crayfish standing on a sandy substrate
Painted Devil Crayfish
Lacunicambarus ludovicianus (syn. Cambarus ludovicianus)
The painted devil crayfish is a burrowing lowland species. In Missouri, it is known from only a few locations in the Bootheel. Its overall color is olive green to blue, with reddish and cream markings.
Photo of a paintedhand mudbug carefully arranged against a black background
Paintedhand Mudbug
Lacunicambarus polychromatus (syn. Cambarus polychromatus)
The paintedhand mudbug is a burrowing crayfish known in Missouri from only a few locations along the eastern border of the Bootheel. It is tan to olive green, and the abdominal segments and tail fan are trimmed with red. The pincers have red spots and red tips.
Photo of a devil crayfish.
Devil Crayfish
Lacunicambarus aff. diogenes (syn. Cambarus diogenes)
The powerfully built devil crayfish is usually a uniform olive or tan, without obvious blotches or spots. It digs underground burrows, often with mud chimneys, and has a wide distribution.
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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.