LIFESCI 1 Lecture 21: wk #8 animals b(bilaterians)
Document Summary
Triploblastic bilaterians (all bilaterians are triploblastic: ectoderm -> skin & nervous system, endoderm -> digestive system, mesoderm -> everything else (circulatory system, organs, muscles, bones, protostome: mouth form first, deuterostome: anus form first. Lophotrochozoans either: suspension feeding structure lophohpores (ciliated tantacles, larval character trochophore (swim & may feed) Platyehlminthes (flatworm): gas exchange by diffusion -> thin, acoelomate. Annelida (segmented worms) terrestrial/aquatic: coelomate, celphalization -> (cid:260)brain(cid:261, digestive tract -> mouth & anus, longitudinal & circular muscles, gas exchange through skin/gills, closed circulatory system -> faster o2 delivery, diversity: polychaetes (marine worms with bristles); leeches. Mollusks: unique: mantle -> excretion , breathing, shell formation, calms, mussels, scallops, oysters, caco3 shells secreted by mantle, high energy stress habitat: suck to the rocks, bivalve: Herbivorous grazers (scrape algae in high tides), strong radula. Strong teeth for scraping rocks: gastropods (snails & slugs) Nudibranchs (sea slugs): aposematic coloration (warning); sometimes eat coral and take its toxin to use for itself: cephalopods (octopus, squid, cuttlefish )
