BIOL108 Lecture Notes - Lecture 22: Circulatory System, Trochophore, Radula

• School: University of Alberta
• Department: Biology (Biological Sciences)
• Course: BIOL108
• Professor: Lien Luong

Document Summary

Mantle: thin layer of tissue that secretes shell. Organs contained in a visceral mass above foot the visceral mass is covered by the mantle. Mouthparts a strap-like rasping organ called a radula. Gills for gas exchange & sometimes for filter feeding. Blood not contained in vessels; just flows throughout the body reduced coelom; not as prominent. Class gastropoda they prey on cnidarians but somehow prevent nematocysts from firing. Of extant mollusc species; e. g. snails and their relatives. Develop trochophore larvae some are terrestrial & freshwater. No larval stage- direct development after hatching (e. g. they look like baby snails) they glide along using muscular contractions of large foot. Slugs" have lost / have reduced shells torsion. Visceral mass twists during development so that the anal open is over head- no clear reason found. Gas exchange land snails & slugs exchange gases using their lung" (lining of mantle cavity) Most are grazers, scrape algae or plants using radula.