While the broader phylogeny of the Oniscideans has not been settled, eleven infraorders/ sections are agreed on with 3,937 species validated in scientific literature in 2004 and 3,710 species in 2014 out of an estimated total of 5,000–7,000 species extant worldwide. Juveniles then go through a series of moults before reaching maturity.

The immature young hatch as mancae and receive further maternal care in some species.

Woodlice have a basic morphology of a segmented, dorso-ventrally flattened body with seven pairs of jointed legs, specialised appendages for respiration and like other peracarids, females carry fertilised eggs in their marsupium, through which they provide developing embryos with water, oxygen and nutrients. Woodlice in the families Armadillidae, Armadillidiidae, Eubelidae, Tylidae and some other genera can roll up into a roughly spherical shape ( conglobate) as a defensive mechanism others have partial rolling ability, but most cannot conglobate at all. They have many common names and although often referred to as terrestrial isopods, some species live semiterrestrially or have recolonised aquatic environments. Woodlice evolved from marine isopods which are presumed to have colonised land in the Carboniferous, though the oldest known fossils are from the Cretaceous period. They get their name from often being found in old wood. Clockwise from top right: Ligia oceanica, Hemilepistus reaumuri, Platyarthrus hoffmannseggii and Schizidium tiberianumĪ woodlouse (plural woodlice) is any crustacean belonging to the suborder Oniscidea within the order Isopoda.

Wood hatch pattern