Hemichordates Hemichordates are a group that have a combination of both invertebrate and chordate characteristics. The hemichordates along with echinoderms and chordates belong to the group deuterostome branch of animal kingdom. Because of their close relationship to chordates these animals are called pre-chordates. The common examples of this phylum are Balanoglossus and Saccoglossus. General characteristics 1 Soft bodied animal and are worm-like. 2 Body is divided into an anterior proboscis, collar and trunk. 3 Body wall is made of unicellular epidermis with mucus-secreting cells. 4 Digestive tract is straight and may show variations. 5 Coleom cavities correspond to each of the three body regions i.e., proboscis, collar, coelomic pouches. 6 Circulatory system consists of a median dorsal and a median ventral vessel. 7 Respiratory system is composed of gills slits forming a dorsal row behind collar. 8 Excretory system has single glomerulus. 9 Nervous system has a sub epidermal plexus of cells and fibers.
