Pereonites

Pereonites are the segments that make up the pereon, the main body section of many arthropods, particularly crustaceans and some myriapods. The pereon is typically located between the head (or cephalon) and the abdomen (or pleon). Each pereonite is a distinct segment of the exoskeleton.

In crustaceans, the pereonites bear appendages called pereopods, which are primarily used for locomotion, such as walking and swimming. The number of pereonites can vary significantly between different crustacean groups. For example, decapods, like crabs and lobsters, have ten pereonites (hence "deca" meaning ten) and typically eight of these bear pereopods, with the first pair often modified into claws (chelipeds). Other crustaceans may have fewer or more pereonites and associated appendages.

In some myriapods, such as centipedes and millipedes, the body is also composed of numerous segments, many of which can be considered homologous to pereonites, and they bear legs. The term "pereonite" is most commonly associated with the field of carcinology, the study of crustaceans. The structure and modification of pereonites and their appendages are key characteristics used in the classification and identification of arthropod species.