Red Swamp Crayfish
(Procambarus clarkii)

Description: Adult red swamp crayfish are colored dark red, whereas juveniles are a drab gray. A blue vein is visible under the tail of this species, and it also has a wedge-shaped black stripe on dorsal side of the abdomen. The texture of the carapace (shell) is rough, and the tail and carapace are not separated by an abrupt space. The pincers are narrow and long and may appear red in subadults. Full-grown adult crayfish can measure 20 cm in length.

Habitat: Red swamp crayfish are tolerant to a wide salinity range and are therefore found in both freshwater and brackish water habitats. They burrow into the muddy banks of sloughs, rivers, swamps and irrigation ditches.

Origin: Southeastern North America.

Invaded Areas: In North America, western states including California.

Concerns: In their native range, red swamp crayfish are economically valuable, for instance as the basis of profitable aquaculture in Louisiana, where they are used for Cajun cooking. They have been intentionally introduced outside their native range for aquaculture operations. They are known to be very aggressive, territorial, and are generalist feeders, making them a formidable threat to organisms that rely on the same resources; in California, they may outcompete native crayfish. They are also known to prey upon endangered newts and are thought to be directly responsible for the decline in newt numbers in some areas. The burrowing behavior of this species can compromise the integrity of banks and levees, thereby increasing erosion and causing destruction to important wildlife habitat.