Cajun Dwarf Crayfish and Swamp Dwarf Crayfish

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

The two species of dwarf crayfish are appropriately named for their size. Both are reddish brown to gray, with a paired series of dark, wavy stripes or dashed lines along the dorsal surface. The tail fan usually has a dark central blotch. The pincers are narrow and long. The two species can be distinguished by examining the male reproductive structures, which are straight in the swamp dwarf crayfish (C. shufeldtii; sometimes called Shufeldt's crayfish) and curved in the Cajun dwarf crayfish (C. puer).

These two dwarf crayfish can be distinguished from the young of other lowland crayfish by the conspicuous dark pigment in the tail fan, and the lengthwise dark stripes or lines on the carapace. Also, the rostrum is flat, without a central troughlike depression.

Size: 
Adult length: 1 to 1 1/2 inches.
Habitat and conservation: 
They are found in shallow, temporary pools during wet seasons, retreating to cells they dig in mud or moist soil during periods of drought.
Distribution in Missouri: 
These small crayfish occur sporadically throughout the Bootheel lowlands, and C. shufeldtii also occurs on the floodplain of the Upper Mississippi River.