Isopods (Woodlice)

This group gathers Crustaceans subcategory members belonging to the order Isopoda, a remarkably diverse crustacean order that has colonized marine, freshwater and fully terrestrial habitats more successfully than almost any other crustacean group. It spans the woodlice, also called pillbugs or roly-polies, among the very few crustaceans to have fully adapted to life on dry land, commonly found under logs, stones and leaf litter in gardens and forests worldwide, marine isopods that scavenge the sea floor, and parasitic species such as the sea lice that attach to the skin and gills of fish. Many terrestrial and aquatic isopods can roll their segmented body into a tight, armored ball when threatened, a defense called conglobation that protects the softer underside from a predator's bite, and most retain gill-like breathing structures inherited from their aquatic ancestry even in species that now spend their entire life on land.