BIOL108 Lecture Notes - Lecture 22: Mollusca, Radula, Gastropoda

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

Document Summary

~ 93,000 named species snails, clams, squids and many others. Calcareous (i. e. , calcium carbonate) shell enclosing soft body. Shell lost or reduced in many taxa moll = soft, originally named for octopuses and cuttlefish. Mantle: thin layer of tissue that secretes shell. Organs contained in a visceral mass above foot. Mouthparts a strap-like rasping organ called a radula. Gills for gas exchange and sometimes for feeding e. g. , bivalves like scallops. Open circulatory system blood not in vessels coelom reduced. Glide along using muscular contractions of large foot gastro = stomach, pod = foot. Single, coiled, tubular shell slugs" are those that have lost shells. Torsion visceral mass twists during development so that anal opening over head why? not exactly clear. But are 1000"s of terrestrial and freshwater spp. direct development. Land snails and slugs exchange gases using lung" (lining of mantle cavity) Most are grazers, scrape algae or plants using radula.