Cannibalistic Crayfish

blog post photo

Perhaps overlooked by many people as a boring crustacean, the crayfish is actually a fascinating species with tons of quirky behaviors. Worms live on their pinchers, they urinate to solicit mating, they’re known to be aggressive and they’ll even eat a smaller crayfish to satiate their appetite.

While many different types of crayfish species have hot tempers, Pacifastacus leniusculus “takes the cake,” according to biologist Carin Anne Bondar, Ph.D, a Vancouver-based crayfish expert. “I’ve seen entire little juveniles – whole – in the gut contents of adults! Moulting represents a huge tradeoff for any arthropod because it requires being ‘soft’ in your new exoskeleton until it hardens up again… If you’ve ever had ‘soft shelled’ crab in a sushi restaurant, you know what I mean. For aggressive animals like crayfish, ‘deciding’ when to moult is tricky. Your conspecifics can prey directly on you very easily when you are soft, but in the long run if you can manage to become a very large individual (lots of moults later), you can become the bully on the block!”

Both male and female crayfish can be aggressive, and they will fight either gender when necessary. “And this doesn’t mean the males always win,” says Carin. “Recent research suggests that if a female is maternal and has babies to look after, she’ll fight hard against aggressive males and will generally win.”

Crayfish are hailed the “freshwater cousin of the marine lobster,” and some recent archaeological findings suggest that crayfish have been on the planet for at least 150 million years. 

Interested in other unique animals? Animal Oddities airs on Wednesday November 10 at 10P et/pt on Nat Geo Wild.

Photo Credit: Carin Bondar, Ph.D


  1. Chuck Worden (txfshrmn)
    Flower Mound Tx
    June 13, 2014, 9:58 pm

    If I find a place of my own I will raise these things. I have so much info on crawdads, you will not believe.