BIOL10005 Lecture Notes - Lecture 27: Dorsal Nerve Cord, Notochord, Starfish
15 Aug 2018
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* mostly marine; some freshwater and damp terrestrial. Generic mollusc characteristics (molluscs have a variation on some basic characteristics): * mantle: dorsal body wall which often forms shell. * mantle cavity: space between mantle and main body where gill (or lungs in terrestrials snails) are found. * muscular foot: used for moving, feeding, manipulation. * head with specialised mouthparts (radula - a rasp-like structure of tiny teeth used for scraping food particles off a surface and drawing them into the mouth) * shell consists of 8 large plates surrounded by a girdle of smaller spicules. *mostly feed on algae or encrusting organisms, but some are predators. * reproduce sexually; some brood their young in their mantle. * characterised by 2 shells; no distinct head. * lost radula; filter feed (sometimes through foot) * gills function for gas exchange and food collection. * marine (e. g. whelks, sea slugs), freshwater & terrestrial. * as a snail develops their body twists (torsion)
