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Today’s Agenda Did you know? Phylum Mollusca notes Correct concept map Review of chordate table Read over Frog Dissection lab for tomorrow Today’s Agenda Did you know? Phylum Mollusca notes Correct concept map Review of chordate table Read over Frog Dissection lab for tomorrow Hand back microorganism tests Today’s Agenda Did you know? Video Portfolio #4 Phylum Molusca Etymology:- From the Latin Molluscus meaning soft of body. 10,000 species known to science most of which are marine. Habitats range from from the arctic seas to small tropical streams and from valleys to mountainsides 7,000 meters high. There are a few adapted to live in deserts and some are parasitic. Characteristics of Mollusca: Bilaterally Organs Body symmetrical. derived from three tissue layers plan: head, foot, and viceral mass covered with a mantle called pallium that secretes the shell (calcium carbonate). Mantle is used in somes species for respiration Some primitive species use one or more pair of gills called ctendia Buccal cavity contains the radula (can be compared to a tongue) which has a ribbon of teeth used for feeding Ventral foot used for locomotion (propelled by combination of cilia and mucus) Mollusks are coelomates (reduced coelom) that includes the kidneys, gonads, pericardium (main body cavity that surrounds the heart) Body possesses a through gut with mouth and anus Has a nervous system with no true brain but two or three pairs of nerve chords contained in visceral mass Has an open circulatory system with a heart and an aorta. Has a pair of kidneys. Reproduction Feed Live normally sexual a wide range of material. in most environments. Mollusk Pests Shipworms – burrow through wood, including docks & ships. Terrestrial snails and slugs damage garden plants. Mollusks serve as an intermediate host for many parasites. Zebra mussels – accidentally introduced into the Great Lakes and reeking havoc with the ecosystem. http://www.cbc.ca/player/play/2454408986 Common Classes Monoplacophora- Chitons Gastropoda- Cowries, Limpets, Slugs and Snails Scaphopoda-Tusk Shells Bivalvia- Bivalves = Muscles, Clams etc. Cephalopoda- Nautilus, Octopus and Squid Class Polyplacophora Includes the chitons Eight overlapping plates Can roll up Live mostly in the rocky intertidal zones. Use radula to scrape algae off rocks. Water flows over gills to respire Class Scaphopoda Includes the tusk shells. Found in subtidal zone to 6000 m deep. Mantle wraps around visceral mass and is fused, forming a tube. Class Gastropoda Gastropoda is the largest of the mollusk classes. 70,000 named species. Include snails, slugs, sea hares, sea slugs, sea butterflies. Marine, freshwater, terrestrial. Slugs lack a shell! Class Bivalvia Bivalve mollusks have two shells (valves). Mussels, clams, oysters, scallops, shipworms. Mostly sessile filter feeders. No head or radula. https://www.youtube.com/ watch?v=m07OvPEoR6g Class Cephalopoda Cephalopods include octopuses, squid, nautiluses and cuttlefish. Marine carnivores with beak-like jaws Surrounded by tentacles modified from their foot.
