Phylum Priapulida retractable (Penis Worms) used in locomotion and in feeding (from “priapos” the greek god of reproduction) has adhesive tubules used to capture prey 17 living & 11 fossil species (Burgess shale) has rows of spiny sensory projections they were probably major predators during the Cambrian (=stylets) cylindrical cucumber shaped worms that live in sand in some species these are elongated into or mud tentacle-like structures .5mm to 30 cm long trunk (abdomen) all marine benthic animals mostly in colder waters covered with tubercles and spines àfrom shores to several 1000 M’s 30-100 superficial rings tail or caudal appendages à marine burrowers hollow some species show high tolerance for hydrogen sulfide and low oxygen levels probably a respiratory organ Body Form also chemoreceptor body divided into: Body Wall proboscis (pharynx or introvert) body wall is covered with cuticle of chitin over epidermis appears somewhat swollen cuticle is molted periodically Animals: Phylum Priapulida; Ziser Lecture Notes, 2015.9 1 Animals: Phylum Priapulida; Ziser Lecture Notes, 2015.9 2 with rows of circular and longitudinal muscles no circulatory system à contractions circulate fluid in body cavity but contraction of body wall circulate fluids in body cavity à also uses hydrostatic skeleton to move along substrate coelomic fluid contains O2 carrying cells and phagocytes circular and longitudinal muscle layers in body wall Nervous System body cavity is pseudocoelom that acts as a haemocoel simple nervous system Feeding & Digestion nerve ring around pharynx most are burrowing predators prominent mid ventral nerve cord with ganglia running the length of the animal feed on bacteria and soft bodied invertebrates no specialized sense organs eversible pharynx nerve endings, probably for the sense of touch in mouth, cuticle is modified into teeth around the mouth a few species are suspension feeders Excretion complete digestive tract excretion via protonephridia (1000’s of solenocytes) contains microvilli to improve absorption drains through urogenital pore terminal anus Reproduction Circulation dioecious Animals: Phylum Priapulida; Ziser Lecture Notes, 2015.9 3 Animals: Phylum Priapulida; Ziser Lecture Notes, 2015.9 4 reproductive system is closely associated with the excretory system eggs and sperm released into water extremely slow development produces a free swimming larva in about 3 weeks Animals: Phylum Priapulida; Ziser Lecture Notes, 2015.9 5 .