Ed Golson Outdoor Education

Rusty crayfish

( Invasive Species )

Scientific Name: Orconectes rusticus

Description: All crayfish look very similar to small lobsters. They should as they are very closely related. They are both crustaceans. What you might not realize is that crayfish and all crustaceans belong to a larger group called arthropods. That's the same group that is home to insects and spiders.  Crayfish are more closely related to insects than they are to fish. 

Most crayfish look very similar, so it's often hard to identify individual species. The rusty crayfish averages about 2 ½ inches in length, not including the claws. Their claws have black bands along the tips. They also have rust colored spots along both sides of their outer covering.  

Habitat: While most invasive species come from foreign countries, the rusty crayfish is originally from the area surrounding the Ohio River in states like Kentucky, Indiana, Ohio, and Illinois. Since the early 1960's however, they have been turning up in many areas around the Great Lakes. They were likely brought here as bait for fisherman and escaped into the environment. Like most crayfish, the rusty crayfish lives in freshwater habitats where there are lots of rocks or tree branches that it can hide under.  

Food: These crayfish eat aquatic plants and insects, fish eggs, and small fish. 

So What's the Problem? These crayfish have very large appetites. They will often eat twice as much as normal crayfish. As a result, they have killed off much of the aquatic plants in many areas. Also, they reproduce very quickly and are so aggressive that larger fish don't want to bother trying to eat them. They are now taking over the habitat that was normally home to many of our native species of crayfish.

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