oniscids

Oniscids, commonly known as woodlice, pill bugs, or roly-polies, are a suborder of terrestrial crustaceans belonging to the order Isopoda. They are among the few crustaceans that have adapted to life on land. Oniscids are characterized by their segmented bodies, typically protected by a hard exoskeleton. Most species have seven pairs of legs.

These creatures are detritivores, meaning they feed primarily on decaying organic matter, such as dead leaves, wood, and fungi. Their role in ecosystems is significant as they help to break down this material, returning nutrients to the soil. Oniscids are found in moist, dark environments, often under logs, rocks, leaf litter, or in damp soil. They are particularly sensitive to dehydration and rely on these humid microhabitats to survive.

Reproduction in oniscids involves internal fertilization. Females carry their eggs in a ventral pouch called a marsupium until they hatch. The young, known as mancae, resemble miniature adults and molt several times as they grow. Some oniscid species, like the pill bug (Armadillidium vulgare), possess the remarkable ability to roll into a tight ball when threatened, a defense mechanism that protects their softer undersides. Despite their common names, they are not insects but are related to shrimp and crabs.