Crustaceans are arthropods , related to insects and myriapods. They are the most diverse animal group in underwater habitats. Only a few crustacean groups have evolved the ability to live on land, and like amphibians, these terrestrial crustaceans still need water or damp places to live. Like all arthropods, crustaceans have a hard (sometimes very hard!) exoskeleton, and jointed legs. Unlike other arthropods, crustaceans have 2 pair of antennae. Sometimes one pair is very small and hard to see.
There are two main crustacean groups that live on land in Michigan. These are isopods and crayfish . Terrestrial isopods are sometimes called pillbugs, sowbugs, slaters, or roly-polies. These little animals have oval-shaped bodies with 14 legs and a hard exoskeleton of overlapping plates. The overlapping plates allow the animal to roll into a ball for protection from predators. Isopods feed mainly on dead plant material, and the fungus and micro-organisms that grow there. They can live in many habitats, as long as they can find some moisture and a dark place to hide. Most kinds of isopods live on ocean shores or on the sea bottom, but a few have spread across the land, far from the sea.
Crayfish look like small lobsters and are closely related to lobsters. They have one pair of big claws and 10 walking legs. Most crayfish live in freshwater, though a few species come out of the water at night to look for food or new places to live. Crayfish are omnivores, eating algae, small animals, and scavenging on larger dead animals too.
Both isopods and crayfish lay eggs, and the females carry their eggs under their bodies until they hatch.