When most adults hear someone mention crayfish, what most likely comes to mind is a culinary dish rooted in the South. However, mention crayfish to a group of Summer Campers at the Lake County Forest Preserves, and you will see eyes light up and hands reach for pond-scooping nets and buckets while their minds contemplate questions of “how big?” and “how many?” During our hikes to the edge of a pond the campers exchange crayfish stories about the best techniques for catching these crustaceans, the size of earlier catches growing the closer we get to the water.
Illinois is home to 24 species of crayfish, which are invertebrates (without a backbone) of the order Decapoda. They are most often found in ponds, streams and wetlands. If you are surprised by the number of local species, you may be even more surprised to learn that new species are discovered all the time. Most recently, Chris Taylor, an aquatic biologist at the University of Illinois, found a whopper that can grow to the size of a lobster. The eager Summer Campers would love to catch one that large, but our ponding buckets are typically filled with critters two to five inches long.
Crayfish are nocturnal scavengers, spending the day under rocks or in burrows topped with “chimneys” made from excavated mud balls. These burrows can be found quite far from a water source and are often mistaken for snake holes. Crayfish emerge from their shelters each night to feed on live and decaying plants, although they won’t pass up live snails, aquatic insects or the occasional fish that swims their way. Crayfish use large front claws to capture, crush and rip their food. Fish such as smallmouth bass, snakes and raccoons are among the few predators that can break through a crayfish’s hard exoskeleton to get a good meal.
The armor-like shell of a crayfish isn’t the only thing it relies on for protection. Their large claws also double as a defense, actively pinching potential predators. More interesting, though, is how they dart backwards to elude would-be attackers. When a crayfish is grabbed, muscles in their back legs contract in a crease at the base of the leg, snapping the leg off quickly. The crayfish then attempts escape by swimming backwards in a darting motion, using its flipper-like tail to propel through the water. The missing leg will regenerate the next time the exoskeleton is shed.
The tail, and the female’s abdomen attached to it, plays an important role in reproduction as well as escape. When the biological clock strikes, a female crayfish secretes a sticky substance that covers the underside of her abdomen. Her eggs attach to this “glue” and stay snug and protected for the weeks (two to 20, depending on species) under the brooding watch of the mother. Newly hatched crayfish stay attached to Mom until they have shed their skin two to three times before swimming off on their own into uncharted waters.
This year at the Lake County Forest Preserves we are celebrating how “Water Connects Lake County” with a variety of programs on this theme. Come search for crayfish at night during our Full Moon Paddle or unearth these crustacean treasures and more at the upcoming Waterfest at Independence Grove. Perhaps you’ll end up with a crayfish tale of your own that rivals those of the Summer Camp kids.