When people think of animals in the arthropod subphylum Crustacea, they probably think about crabs, lobsters, and shrimp. That would be unsurprising since they’re the crustaceans most people come in contact with, usually as dinner. For most people, however, there are much more common crustaceans all around them.
Woodlice (order Isopoda, suborder Oniscidea) are unique among crustaceans for being terrestrial. Also known as sowbugs, these little arthropods can usually be found in or under fallen logs or rotting wood in damp environments. Although they live on land, they still require considerable moisture in order to breathe.
These crustaceans feed mostly on plant material, usually decaying plant matter found near the soil. They can, however, feed on sufficiently moist and tender seedlings, and have been known to be crop pests.
Sowbugs in the family Armadillidiidae (also known as pillbugs) can roll themselves into defensive balls. The sowbug above is not in this family. Most sowbugs are incapable of rolling into balls, and either freeze in place or scurry for cover. The individual above kept trying to run away from me, but paused just long enough to get this picture.