Look out for the lawn lobster! Did you know you might find crayfish in your yard? Or in the meadow nearby? We mostly think of them as living in streams and creeks, but they can actually live down below the soil. There is water deep beneath the ground, and that’s where they make themselves at home.
The crayfish you are most likely to find in your yard is the devil crayfish, Cambarus diogenes. It’s also known as the chimney crayfish. Or crawfish. Or even crawdad. Clearly, it’s hard to pick just one name!
What gives these crayfish away is that they build chimneys as the entryways to their homes. These “chimneys” don’t have fires like human chimneys. Instead, they look like little balls of mud stacked around a hole until they have a whole tower built up. You can find them in fields, yards and along streambanks.
Scientists aren’t sure exactly why they build a chimney instead of just creating a hole. Maybe you’ll be the scientist to discover their exact reasoning!
Words to know
Exoskeleton: A rigid external covering of the body of some invertebrates.
Molt: To shed old feathers, hair, skin or shells to make way for new growth.
Pleopod: A forked swimming limb on a crustacean.
Devil crayfish are crustaceans and resemble small lobsters, which makes sense because they’re cousins. Their hard exoskeleton — a skeleton on the outside of their bodies — protects them from predators.
They can be dark reddish-brown to gray in color. People have even come across bright red and blue devil crayfish. They have 10 legs and a pair of claws. While underwater, they use gills underneath their body to breath. Males have larger claws than the females. They never get too big, though. The longest devil crayfish is only 2.4 inches long. That’s only a little longer than an AA battery!
Baby crayfish hold onto their mothers while they’re very little. They hold onto her pleopod, a part of her abdomen near her tail that can curl underneath her. Once they are large enough, they let go, but their coloring is clear to help them hide from predators.
Because they have an exoskeleton, they molt to get bigger. That means their bodies grow, and when it’s time, their exoskeleton gets very thin. Then their new, bigger exoskeleton bursts through, and they are now a little bigger! Their new exoskeleton gets darker and darker as they get older, which is how they change from clear to their adult coloring.
Our devil crayfish may seem like they’re in a world all their own, but lots of life depends on them. In fact, an endangered species needs them to survive. The Hine’s emerald dragonfly only uses the tunnels of the devil crayfish to lay its eggs. These dragonflies won’t lay their eggs anywhere else.
Baby dragonflies spend their first several years of life underwater, and the Hine’s emerald dragonfly chooses devil crayfish tunnels to grow up in. Without the devil crayfish, these dragonflies wouldn’t be around at all. All life is connected, even in mysterious ways!
While you’re out discovering why the devil crayfish makes those chimneys, maybe you’ll also discover why the Hine’s emerald dragonfly only likes those tunnels and water sources.
If you find a chimney in your yard, you can be proud that a lawn lobster thinks your yard is a safe place to be. And you can rest assured that the whole world under your feet is busy and happy.
____________ Follow Willy's Wilderness on Facebook for more kid-friendly nature stories and activities.