The evolution of segmentation in Crustacea is the formation of sclerotized and jointed body somites and arrangement of somites into tagmata, is viewed in light of historical traits and functional constraints. The larvae stages provide us with insight on their structural equipment. The variety of evolutionary levels including lobopodians, tardigrades, and pentastomids also allows interpretations far beyond the Crustacea. The principal strategy of arthropods is the simultaneous development of head somites, as expressed in a basal "head larva,"The principal strategy of arthropods is the simultaneous development of head somites, as expressed in a basal "head larva". This can be recognized in the developmental patterns of extant and fossil representatives of several crustaceans.