Crayfish


Crayfish, order Decapoda

About

Crayfish are classified in the order Decapoda. They are separated into 2 families: Astacidae (western Eurasian and western North America) and Cambaridae (eastern Asia and eastern North America). Crayfish are somewhat tolerant of impairment.

Habitat

Crayfish live in freshwater lakes and streams that do not freeze to the bottom. Crayfish can usually be found hiding under rocks and logs.

Diet

Most crayfish prefer feeding at night, when they will eat snails, algae, insect larvae, worms, tadpoles, small fish, and vegetation. Crayfish are also scavengers, and will eat almost anything that is dead.

Reproduction

Crayfish become sexually mature and mate in the October or November after they’re born, but fertilization and egg laying usually occur the following spring. The fertilized eggs are attached to the female’s swimmerets on the underside of her jointed abdomen. There the 10 to 800 eggs change from dark to translucent as they develop. The egg-carrying female is said to be “in berry,” because the egg mass looks something like a berry. Females are often seen “in berry” during May or June. The eggs hatch in 2 to 20 weeks, depending on water temperature. The newly hatched crayfish stay attached to their mother until shortly after their second molt.

Life Cycle

Crayfish don’t have distinct morphological phases (baby crayfish look like small versions of adults). Since they are covered in a hard exoskeleton, they must molt as they grow. To molt, a crayfish will find a place to hide and crack its way out of its old exoskeleton. Recently molted crayfish are very vulnerable because their new exoskeleton is very soft at first.

Other

Crayfish are also called Crawfish, Mudbugs, and Crawdads. They are eaten as a delicious dish in Europe, China, Africa, Australia and the United States.

Click here for more information about crayfish from the VA Cooperative Extension.

References

  1. “Crayfish.” Wikipedia. http://en.wikipedia.org/wiki/Crayfish#Names
  2. “Crayfish Information.” The Crayfish Corner, http://www.mackers.com/crayfish/info.htm#behaviour

For more crayfish pictures, click here
Research conducted by StreamWatch volunteer Zach Pierson