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Feature of isopod anatomy
Pleopodal lungs are an anatomical feature of terrestrial isopods and a component of their respiratory system. They are ancestrally derived from pleopodal gills, and they facilitate gas exchange on land. They perform a function similar to spiracles in insects.
Pleopodal lungs are identifiable on woodlice as white patches on the lower five segments (the pleon) on the ventral side (underside). The number of pleopodal lungs varies by species: they may have up to five pairs, or only two pairs as in Porcellio laevis; a minority of species lack pleopodal lungs entirely.