In almost every stream and river, and some ponds, we have “miniature lobsters”. Much smaller, but packing muscular pincher claws that they use to catch their prey and defend themselves, crayfish patrol our water systems. During the day, most are usually found under rocks (a few, like Digger crayfish, are in underground and underwater tunnels), but at night they creep out and look for food. Like nature’s janitors, they clean up by eating anything decaying (like dead fish, dead leaves and algae), and will also eat whatever small animals they can catch. In turn, they are tasty snacks for raccoons, mink, herons, fish like bass and catfish, and many other predators. In other words, they are important links in aquatic food chains.
Take a look for crayfish under rocks in a local stream or river (kids should always be with an adult near rivers, of course). All you need is a net or even a kitchen sieve, and a container to put them in. And you can tell male from female easily – just check out the video. Males have enlarged swimmerets under their tail that extend forward under their back legs (for depositing sperm). Try picking them up, and see if you can tell the difference! Don’t forget to put the rocks back where you find them, and release the crayfish (and other critters you may discover) soon.
The ones in the videos are probably Common crayfish. Unfortunately in some areas of Ontario Rusty crayfish have been released. These larger crustaceans have reddish patches on either side of their cephalothorax, and black-tipped claws. They can out-compete and sometimes replace our native species. It’s important to never release crayfish (or other animals) far from where they were found or purchased for bait or pets.