A woodlouse is any crustacean belonging to the suborder Oniscidea within the order Isopoda. They get their name from often being found in old wood, and from louse, a parasitic insect, although woodlice are neither parasitic nor insects.
Whole woodlouse.
Woodlice under a concrete block.
Hemilepistus reaumuri lives in "the driest habitat conquered by any species of crustacean".
Ligia oceanica is aquatic.
Crustaceans are a group of arthropods that are a part of the subphylum Crustacea, a large, diverse group of mainly aquatic arthropods including decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, opossum shrimps, amphipods and mantis shrimp. The crustacean group can be treated as a subphylum under the clade Mandibulata. It is now well accepted that the hexapods emerged deep in the Crustacean group, with the completed group referred to as Pancrustacea. The three classes Cephalocarida, Branchiopoda and Remipedia are more closely related to the hexapods than they are to any of the other crustaceans.
Image: Sally Lightfoot crab (4202519454)
Image: Humarus gammarus 1
Image: Procambarus clarkii
Image: Lysmata amboinensis in Tropicarium Oceanarium Budapest