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Mollusks

Mollusks. Mollusks. Coelom : Fluid filled body cavity A circulation system helps carry nutrients and oxygen to the tissues and removes wastes and carbon dioxide. Blood moves by one ore more muscular hearts Mollusks : Have no segmented bodies Have 3 distinct regions

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Mollusks

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  1. Mollusks

  2. Mollusks • Coelom: Fluid filled body cavity • A circulation system helps carry nutrients and oxygen to the tissues and removes wastes and carbon dioxide. Blood moves by one ore more muscular hearts • Mollusks: Have no segmented bodies • Have 3 distinct regions • Visceral Mass: Central section that contains the body’s organs • Head • A foot: muscular region

  3. Mollusks • Share the following characteristics • Body Cavity: Have a true coelom which is around the heart • Symmetry: Have bilateral symmetry and 1 or more shells called valves • Organ Systems: Circulation, respiration, digestion and excretion • Three- part body plan: (muscular foot, head and visceral mass)

  4. How Mollusks Breathe • Breathe with ciliated gills located in their mantle cavity if in the water • Mantle cavity becomes the lung when on land

  5. Mollusk Circulation • 3 chambered heart and an open circulatory system • Blood leaks out of blood vessels and bathes the body’s tissues directly • Only octopuses and squids have a closed circulatory system where blood stays in the blood vessels (Nutrients pass through by diffusion) • 2 of the heart’s chambers collect blood from the gills • Third chamber pumps oxygenated blood out of the vessels and into spaces of the mollusk’s tissues

  6. Excretion • Wastes are collected in the coelom where helpful molecules are recovered from body fluids before wastes are discharged from the animal

  7. Gastropods • (Snails and Slugs) Use muscular foot to crawl and their mantle causes a hard protective shell • Move using muscular foot and secrete a mucus from the base of their foot which allows them to glide along the path. • Terrestrial snails: Herbivores • Other gastropods are carnivores. They drill a hole into other shells and suck the tissue out.

  8. Bivalves • (Clams, Oysters and Scallops) Secrete a two-part shell (Valve) with a hinge. Feed by drawing water into their shells and filtering out food particles • Use their muscular foot to dig into the sand where they live

  9. Cephalopods • (Octopuses and Squids) Most of their body is a head attached to tentacles • Octopuses: 8 tentacles • Squids: 10 tentacles • Eat fish, mollusks, crustaceans and worms • Modified cavity that creates a jet propulsion system to propel them rapidly through the water

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