Nemertea (proboscis worms) Unique anterior proboscis surrounded by fluid filled cavity (rhynocoeol); complete digestive tract (mouth and anus); circulatory system with closed vessels
Mollusca (clams, snails, and squids) coelomates with three main body parts (muscular foot, mantle, visceral mass); coelom reduced; main body cavity is a homocoel
Annelida (segmented worms) coelomates with body wall and internal organs (except digestive tract) segmented
Nematode (roundworms) cylindrical, unsegmented pseudocoelomates with tapered ends; no circulatory system
Arthropoda coelomates with segmented body; jointed appendages, exoskeleton from ectoderm
Echinodermata (sea stars and sea urchins) coelomates with secondary radial anatomy (larvae bilateral; adults radial); unique water vascular system; endoskeleton
Chordate (lancelets, tunicates, vertebrates) coelomates with notochord; dorsal hollow nerve cord; pharyngeal slits; muscular postanal tail