(phylum Arthropoda, subphylum Crustacea)
A superorder of crustaceans that possess a brood chamber (marsupium) beneath the thorax into which the eggs are deposited and where they are fertilized. Development of the young is direct. Most peracaridans are small. Approximately 40% of all crustaceans belong to this superorder, which includes seven orders: Amphipoda, Cumacea, Isopoda, Mysidacea, Spelaeogriphacea, Tanaidacea, and Thermosbaenacea.
Subjects: Zoology and Animal Sciences.