Transcript Mollusks
Mollusks Characteristics of Mollusks Mollusks are invertebrates Mollusks have soft bodies Mollusks have bilateral symmetry Mollusks have a digestive system with 2 openings Mollusks have an open circulatory system • THINK! – What does it mean to have an open circulatory system? Blood does not travel in vessels throughout the entire body. Structure of Mollusks Although they don’t look much alike at first, a snail, a clam, and a squid have the same basic body structure. • Shell – hard outer covering • Gills – organs that remove oxygen from water • Mantle – a thin layer of tissue that lines the internal organs; it secretes the hard shell • Digestive tract – stomach plus intestines • Foot – used for crawling, digging, or catching prey Groups of Mollusks: Gastropods Examples: Snails & Sea Slugs Characteristics: • Has a single shell or no shell at all • Eats using a radula, a flexible ribbon of tiny • teeth to obtain food. Moves by oozing mucus along its broad foot Groups of Mollusks: Bivalves Examples: Oysters, Clams, Scallops, & Mussels Characteristics • • • They have 2 shells held together by hinges They are filter feeders that strain the water for food They do not move quickly; adults stay in one place or use their foot to move very slowly • THINK! – Which bivalve do you think is able to move? • Clams dig into the mud by changing the shape of its foot Groups of Mollusks: Cephalopods Examples: Octopuses & Squids Characteristics: • • • Captures its prey with muscular tentacles, crushes the prey with its beak, and cuts the flesh with its radula Has large eyes, excellent vision, and large brains. They are capable of learning! They swim by jet propulsion squeezing water out of a tube called a siphon Mollusks In the News and Video For many years, it has been rumored that giant squid existed but only dead carcasses of a few have been found along some beaches. None have been seen alive. Until now… Live Giant Video_0113 Mollusks In the News and Video A study emerged in March 2008 in which scientists have found that the hard and soft materials of a Humboldt squid’s beak may be used to improve artificial limbs for humans. The squid’s beak is like placing a razor blade in a bowl of Jell-o but, because the beak is soft towards the bottom and sharp only towards the top, it does not harm the squid’s body but can still pierce its prey. • “We could maybe imagine creating a full prosthesis that mimics the chemistry of the beak, so that it matches the elasticity of cartilage on one side and on the other side you could create a material which is very stiff..” VIDEO – Smartest Animals_Octopus & Squid? 4min2sec Deep-Sea ‘Dating’ Video Clip Amazing Fish Changes Its Stripes Cuttlefish Dating http://abcnews.go.com/search?searchtext=squid&type=