Wild Fact #756 – Be Afraid of the “Claw” – Rusty Crayfish

Photo by Jeff Gunderson, Minnesota Sea Grant

I was having a tough time choosing an animal for today’s Wild Fact when I suddenly remembered talking about the Rusty Crayfish the other day.  I thought this interesting and highly competitive Crayfish would be perfect for a Friday Fact.

The Rusty Crayfish isn’t your normal everyday crayfish. I am willing to bet that you if you gave a regular crayfish steroids that it would end up being like good ol’ Rusty.  You see the Rusty Crayfish is large, very aggressive  and spreading rapidly across North America.  This invasive species is beginning to displace our regular, native crayfish here in Canada.  Not only are these particular crayfish more aggressive but they also have bigger claws. Some scientists have found that fish will actually avoid eating the Rusty Crayfish in favour of the more docile, native ones.  When working for the Province of Ontario I had heard reports of this mean crayfish actually putting up a fight with a Smallmouth Bass.  This might be a new technique for fisherman, start using bait that attacks the fish.

So what do these big guys feed on? Well, they like your typical aquatic food such as snails, leeches, aquatic worms, plants, insects and of course small fish.  Believe it or not the Rusty Crayfish will not only consume aquatic vegetation but they will also clip the plants at the base using their large claws. Researchers believe that this destruction of vegetation allows for greater population expansion.  By removing vegetation they are reducing the amount of key habitat for juvenile sunfish.  Therefore this leads to a reduction in sunfish populations which are a major predator on baby Rusties.  If this theory is correct than I am absolutely impressed with Mother Nature right now. How incredible is it that a species is controlling their predators by removing their habitat? Hey, wait a minute! I am a Habitat Biologist whose job is to ensure “no net loss” of fish habitat.  I wonder if I should charge the Rusty Crayfish for violating the Fisheries Act?

Rusty Crayfish Fast Fact – Just before the female crayfish lays her eggs she will develop white patches on the underside of her tail. These white patches are actually a mucus-like substance created during egg fertilization and development. If you ever find a Rusty Crayfish with white patches you will be able to dazzle your friends with this little bit knowledge.

Have a great weekend everyone! See you first thing Monday morning.

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  1. Larissa 7 years ago
    • Nathan Nathan 7 years ago
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