Isopoda

Armadillidium vulgare. Image credit: Ron Matsumoto (https://eol.org/pages/1021952/media)

The isopoda group includes various crustaceans such as woodlice (e.g., pillbugs). These organisms possess a rigid and segmented exoskeleton, two pairs of antennae, seven pairs of jointed limbs on the thorax, and five pairs of branching appendages on the abdomen. Terrestrial isopods play an important role in many tropical and temperate ecosystems by aiding in the decomposition of plant matter through mechanical and chemical means, in turn enhancing and providing resources for the activity of microbes. Many species can roll themselves into a ball, a behavior mechanism that helps conserving moisture.