They use their mouth and claws to excavate, carrying mud pies to the surface, piling it up beside the burrow which allows them to stay close to safety if a predator comes along. Some of these so-called "terrestrial" crayfish dig water-filled tunnels that they inhabit in cooler months. These crawdads are often eaten by humans, and also used as a fishing bait.Ĭrayfish mostly live in lakes, rivers and streams, though some can spend a great deal of time on land, such as the upland burrowing crayfish.
Right: A virile crayfish ( Orconectes virilis) from Leech Lake in Minnesota. A “ tail-flip” is an instinctive reaction that propels the crayfish backward, away from a potential predator or disturbance. Their tail fans can curl under the body, which help to protect eggs. Under the main part of their tail are small appendages called swimmerets that help them move and assist with carrying eggs. To grow bigger, they must shed their skins, or molt, and form a new exoskeleton.Ĭrayfish have a long rostrum, a pointed structure in the front of their heads that looks like a nose but is thought to offer protection for their compound eyes. Here’s why.)Ĭrayfish also all wear the same costume, so to speak-their exoskeletons are made of a tough chemical called chitin. ( Related: Animal blood comes in a rainbow of colors. Others are simpler, such as the beige-and-brown calico crayfish of the midwestern and eastern U.S.Īll crayfish have blue blood due to the copper-based pigment hemocyanin. Then there’s the Murray spiny freshwater crayfish of Australia, which sports punk-rock spikes. Some are flashy, such as the New Guinea’s thunderbolt crayfish, with dazzling pink, purple, and blue hues. They come in a range of shapes and sizes. The noises made are likely used for communicating with other crawdads, and to alert others to the presence of predators. Though they don’t exactly sing, these little decapods do produce sounds both in and out of water.Ī thin appendage that draws water and air through the gills makes a noise called a “ pulse train” that sounds a bit like Morse code. They eat just about anything they can get those chelae on, including insects, algae, fish, invertebrates, carrion, and plant detritus. The southeastern United States and, to a lesser extent, Australia, are considered crayfish diversity hot spots. There are nearly 600 known species of these creatures, with new varieties found every year. Two of these legs are modified into large claws, called chelae, used for defending themselves and snagging food.
These animals have 10 pairs of walking legs, hence the Latin name for the crayfish order, known as Decapoda (“ten-footed”). Crayfish, or crawdads, are crustaceans that live in freshwater environments throughout the world, except for India and Antarctica.
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