Isopoda
Isopods, Woodlice, Pill Bugs & Relatives
Isopoda is a large and diverse order of crustaceans in the class Malacostraca. Found in marine, freshwater, and terrestrial environments across every continent including Antarctica, isopods are one of the most successful crustacean lineages on Earth. They are characterised by a flattened body, seven pairs of walking legs (pereopods), and the absence of a carapace. Many species are important decomposers and form an essential part of nutrient cycling in their ecosystems.
Armadillidium sp. — generalised dorsal view
Sub-orders of Isopoda
Select a sub-order to explore families, genera, and species within.
Oniscidea
Terrestrial Isopods
Terrestrial — leaf litter, soil, rotting wood, rocky crevices
Oniscidea is the suborder containing all fully terrestrial isopods — commonly known as woodlice, pill bugs, roly-polies, and sow bugs. They have evolved a rem…
Explore →Asellota
Aquatic Pill Bugs
Freshwater streams, ponds, lakes, and coastal marine environments
Asellota is a large suborder of primarily freshwater and marine isopods. The freshwater species (especially Asellus aquaticus) are popular in aquatic vivariums,…
Explore →Valvifera
Marine Isopods
Marine — seaweed, rocky coastlines, subtidal zones
Valvifera are predominantly marine isopods characterised by a pair of plate-like appendages (uropods) that fold under the abdomen to protect the pleopods. They …
Explore →Cymothoida
Fish Lice & Relatives
Marine; parasitic species attached to fish hosts
Cymothoida includes both free-living and parasitic isopods. The parasitic Cymothoidae ("fish lice") are well-known for attaching to fish hosts, while the Gnathi…
Explore →Featured Species
Highlights from the Isopodex community index.