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http://www.youtube.com/watch?v=Gg57Idz7Bs4 http://www.youtube.com/watch?v=vP_td9q_344. General. Name means soft body this is one of the largest animal phyla, besides Arthropoda There are nearly 75,000 species and some 35,000 fossil species Very diverse group (snails, clams, octopus)
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http://www.youtube.com/watch?v=Gg57Idz7Bs4 • http://www.youtube.com/watch?v=vP_td9q_344
General Name means soft body this is one of the largest animal phyla, besides Arthropoda There are nearly 75,000 species and some 35,000 fossil species Very diverse group (snails, clams, octopus) Range from simple organisms to some of the most complex invertebrates
Ecological Relationship Habitats: from tropics to polar region ponds, lakes, streams, surf, ocean depths, etc Most live in the sea Include herbivores, carnivores, and filter feeders
Economic Importance many are food for humans produce pearls (most from Eastern Asia) Some molluscs are destructive (Great Lakes, Snails and Slugs in gardens)
Form and Function Body Plan – • consist of head-foot portion (cephalopod) and a visceral mass (nervous system) • head-foot portion – contains feeding, cephalic sensory, and locomotion organs • visceral mass – contains digestive, circulatory, respiratory, and reproductive organs
Form and Function Body Plan – two folds of skin make up a protective “mantle” mantle houses the lungs and secretes a shell in many species
Form and Function Head-foot – many have a well developed head containing sensory organs range from simple to complex eyes Foot is used for locomotion
Form and Function Head-foot – Unique structure inside mouth called “radula” It is a tonguelike found in all molluscs except bivalves (shell fish) Has rows of tiny teeth that point backward It has about 250,000 teeth When protruded, it can scrape, pierce, tear, or cut food material http://www.youtube.com/watch?v=mLVDwlrSq5U&list=TLDlxJTSuqf42kySqHbo0jexNdvt3BkIqS
Form and Function Head-foot – Foot can be adapted for locomotion, attachment, or a combination of functions Some modifications include – “hatchet foot” of bivalves, funnel for jet propulsion in squids and octopi
Form and Function Visceral Mass – (mantle and mantle cavity) mantle – the outside of the skin extending from the visceral hump that runs down each side of the body, protecting soft parts and creating a space
Form and Function Visceral Mass – (mantle and mantle cavity) mantle cavity – houses respiratory organs products from digestive, excretory, and reproduction systems empty into the mantle cavity in aquatic species, surface cilia create water currents that continually flush out waste
Form and Function Visceral Mass – Shell (when present) typically has three layers outer layer Composed of a protein called “conchiolin” Growth only occurs at the edge of the shell middle layer Composed of densely packed prisms of calcium carbonate in a protein matrix Inner layer Composed of calcium carbonate sheets laid down over a thin protein matrix This layer is continuously secreted by mantle surface, so it becomes thicker during the animals life Calcium for the shell comes from environmental water, soil, or food
Form and Function Internal Structure and Function – there is an open circulatory system pumping heart blood vessels blood sinuses closed circulatory system
Form and Function Internal Structure and Function – Digestive tract is highly specialized according to feeding habits Most have a pair of kidneys Ducts of kidneys in many forms serve to discharge eggs and sperm
Form and Function Internal Structure and Function – Nervous System consists of several pairs of ganglia (nerve cells) with connected nerve cords Most molluscs are dioecious Some are hermaphroditic
Mating Leopard Slugs https://www.youtube.com/watch?v=FhVi4Z6CjZk
Class Polyplacophora: Chitons are somewhat flattened and have a surface that bears eight plates, or valves name means “bearing many plates” most are between 2 and 5 cm commonly occur on rocky surfaces in intertidal regions if detached, they can roll up like an Armadillo for protection Sexes are separate
Class Gastropoda (gastro – stomach, podos – foot) By far the largest and most diverse class Contains about 40,000 living species Includes snails, limpets, slugs, whelks, conchs, periwinkles, sea slugs, sea hares, sea butterflies, etc. Often sluggish, sedentary animals Because of heavy shells and slow locomotion organs
