The Signal Crayfish, Pacifiastacus leniusculus, is a North American species of Crayfish. This lobster-like crustacean varies in color from bluish-brown to reddish brown, but cook up red. They are named for the white oval patch near the claw hinge which look like the white flags that signalmen used to direct trains back in the day. These wild Crayfish are caught in traps in the deltas of California.
The Signal Crayfish is a voracious predator. They dine on a variety of fish, frogs, invertebrates, plants and its own species. Signal Crayfish are have almost wiped out the White-clawed Crayfish and become invasive predators in Europe and Japan. They can also cause damage to waterways by burrowing into banks. Fortunately, they are very tasty.