Field Guide

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.

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.

Adult White River crawfish are usually a deep burgundy red with a black V-shaped stripe on the abdomen. Juveniles are gray with dark spots scattered over the carapace. In Missouri, this species mostly occurs in the Bootheel and north along the Mississippi River.

The calico crayfish is rather plain: gray-green with a pale central zone along the middle of the carapace and abdomen. The pincers are orange-tipped, and in mature males are tinged with purple. It is usually only found in the northern half of the state.

The elktoe is one of many Missouri mussels with a declining population.

Most people are repulsed by leeches. But once you get past the fact that many species are parasitic bloodsuckers, you will discover that they are fascinating creatures with an important role in nature.

Bryozoans are tiny, filter-feeding invertebrates. They create colonies that can be mossy, branching, or round and jellylike.