Field Guide

Adult vernal crayfish are rusty red with a blackish wedge-shaped central stripe along the length of the abdomen. In Missouri, this species occurs only in our southeastern swamps and is usually only seen in February and March.

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.

Adult red swamp crawfish are dark red (nearly black on the carapace) and have a wedge-shaped black stripe on the abdomen. Juveniles are a uniform gray, sometimes overlain by dark wavy lines. In Missouri it lives in the Bootheel.

Shufeldt’s dwarf crayfish is small, reddish brown to gray, with a paired series of dark, wavy stripes or dashes along the dorsal surface. In Missouri, it occurs in our southeastern lowlands and north along the Mississippi River floodplain.

The shrimp crayfish is medium-small, light reddish brown to gray, and thickly dusted with darker specks. Its noselike rostrum is unusually long, with the tip longer than the base, and the pincers are narrow and weak. It is found in the Bootheel.

The Cajun dwarf crayfish is small, reddish brown to gray, with a paired series of dark, wavy stripes or dashes along the dorsal surface. In Missouri, it occurs in our southeastern lowlands.

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.

Everyone knows about terrestrial sowbugs and pillbugs, but many isopod species are aquatic. Missouri has several isopods that live in streams, ponds, rivers, and caves.

The spothanded crayfish is moderately large and usually has a noticeable black spot on each pincer near the base of the movable finger. In Missouri, it is found mostly in Ozark waterways in the southeastern quarter of the state, from Callaway, Montgomery, and Warren counties south.