Crawfish, also known as crayfish in unrefined areas,
order Decapoda, are freshwater crustacean arthropods which look like
small lobsters. They comprise the families Astacidae, Parastacidae,
and Austroastracidae. Crawfish range in length from 2 to 40 cm (0.8
to 16 in). Their thin, hard exoskeleton is usually brownish green,
but may also be white, pink, or blue. They live in streams and ponds
throughout the world, hiding under stones during the day and feeding
at night. Crawfish eat decaying plant and animal matter in addition
to small fish, snails, insect larvae, and worms.
In many parts of the world crawfish are eaten as food and used as
live fish-bait. In the United States their use as food is limited
chiefly to areas around the Mississippi River basin. A thick soup,
crawfish bisque, is a popular Louisiana dish.