The crayfish (also known as crawfish) is one of the most interesting of the aquatic animals because of its large size and impressive pincers. These claws are important tools for catching food and for defense. Watch how it moves sideways or shoots backwards as if jet propelled. Its periscope eyes help it hunt for food and see danger in all directions. Its gills can't be seen, they are under the hard body shell. The crayfish is an omnivore, hunting mostly at night. It prefers a meal of plants and dead animals but will catch its dinner if given a chance. In the spring look for eggs or young attached under the female's tail.
If your crayfish has a rusty spot on its shell, it is an alien invader or exotic. The "rusty" crayfish was accidentally introduced into Wisconsin and wherever it is introduced, it causes problems. In some northern Wisconsin lakes it has eaten most of the aquatic plants, hurting the quality of the lakes. Fish that normally eat crayfish don't like the feisty, aggressive "Rusty." It takes over the homes of native crayfish and has been known to eat fish eggs. It is illegal to transport live crayfish from one place to another or to use live crayfish for fishing bait.