The Signal Crayfish (Pacifastacus leniusculus) is a freshwater crustacean. Crustaceans include shrimp, lobsters, and crabs.
The Signal Crayfish has a hard, bluish-brown to reddish-brown exo-skeleton (outer shell), called a carapace. It has a white to pale blue-green patch near its claw hinge like a white signal flag. It is a decapod because it has 10 clawed limbs, with two large, smooth, front claws called nippers. It has eye stalks. It has gills to breathe oxygen from the water. Its abdomen has six segments, ending with a fan-shaped tail called a telson.
It grows to about 6-10 centimetres (2-4 inches) in length.
The Signal Crayfish is native to the waters of North America. It prefers freshwater rivers, lakes, and streams. It is benthic because it lives on the bottom of the river, walking on the sandy floor.
It is nocturnal, active mostly at night. During the day, it rests in a burrow or rock crevice.
It is an omnivore and detrivore, eating a range of food including dead aquatic material. Its predators include eels, fish, otters, and muskrats.
The female lays 200-400 eggs, carried under her tail on her swimmerettes. The eggs hatch after 14-21 days into juvenile crayfish.
Its lifespan is about 30 years.
Photographer: Martina Nicolls
Martina Nicolls: SIMILAR BUT DIFFERENT IN THE ANIMAL KINGDOM