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Saddlebacked Crayfish

Orconectes medius
Family: 
Cambaridae (freshwater crayfish) in the order Decapoda (shrimp, crabs, and lobsters)
Description: 

The most obvious feature of this crayfish is the bold blackish band (saddle mark) across the hind margin of the carapace; note also the absence of dark blotches or specks. Another dark bar crosses the head just in front of the cervical groove (the groove separating head from thorax). The pincers are broad and powerful. Similar species within the range of this species are the golden crayfish (Orconectes luteus), which has a darker abdomen and red on many body parts, and the belted crayfish (O. harrisoni), in which the forwardmost saddle spans the cervical groove.

Size: 
Adult length: about 1 to 2 1/2 inches.
Habitat and conservation: 
Occurs most often in small to medium-sized creeks having clear, permanent flow and stable, rocky bottoms. This crayfish digs shallow burrows beneath rocks.
Distribution in Missouri: 
Confined to the Ozark Region of Missouri, where it is found only in the Meramec River and Big River drainages, but not in the adjoining Bourbeuse drainage.
Status: 
In many small streams where it is found, it is the most abundant crayfish.
Shortened URL
http://mdc.mo.gov/node/6339