Northern Crayfish (Virile Crayfish)

Oronectes virilis
Cambaridae (freshwater crayfish) in the order Decapoda (shrimp, crabs, and lobsters)

The northern crayfish (sometimes called the virile crayfish) is reddish-brown or green without prominent markings. The pincers are green with orange tips and in adults are conspicuously studded with whitish knobs. Paired dark blotches run lengthwise along the abdomen. The rostrum has conspicuous notches or spines near its tip.

The virile crayfish is the largest of crayfish in the Prairie Region and in the state. The calico (“papershell”) crayfish (O. immunis) differs from this species in having pincers that are gray or purple, a pale lengthwise stripe along the middle of the carapace and abdomen, and a rostrum without lateral notches or spines.

Adult length: to about 5 inches (or more).
Habitat and conservation: 
In the Prairie Region this crayfish is very abundant in the pools of rocky streams. It occurs in fertile, warm, moderately turbid streams without a strong base flow and prefers abundant cover of slab rocks, logs and organic debris. Also occurs in some artificial ponds.
Adults are primarily nocturnal; this active, alert, agile crayfish feeds on a variety of plant and animal material, both living and dead.
Distribution in Missouri: 
Effectively statewide: The native range encompasses all of Missouri's Prairie Region and a band of streams along the northern and western border of the Ozarks. Widely introduced elsewhere. Absent from the southeastern lowlands and parts of the central Ozarks.
This species is called the northern crayfish because it occurs farther north in Canada than any other crayfish. Its broad range comprises the southern tip of Hudson Bay, New England, western Montana, Oklahoma, and northern Arkansas. It has been widely introduced elsewhere, as it is a popular fishing bait.
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