Isopods are a type of non-insect arthropod, or crustacean. Most isopods live on land, however there are approximately 100 North American aquatic species, mostly belonging to the family Asellidae. They tend to be rather flat from top to bottom (depressed), not laterally. They often have mottled coloring. These are usually bottom dwelling sprawlers, found in shallow, freshwater habitats. Usually they are omnivores or detritivores.