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Mollusks Phylum: Mollusca. Characteristics: Invertebrates Soft, unsegmented bodies Bilateral symmetry Has a mantle Has a foot. Mollusks. Snail. Key:. Digestive Tract. Gills. Foot. Shell. Mantle.
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MollusksPhylum: Mollusca Characteristics: Invertebrates Soft, unsegmented bodies Bilateral symmetry Has a mantle Has a foot
Mollusks Snail Key: Digestive Tract Gills Foot Shell Mantle Mantle- thin layer of tissue that covers internal organs and produces the hard shell in many mollusks Open circulatory system- blood is not inside vessels (it sloshes over organs and returns to the heart) Gills-organs that remove oxygen from water Foot- organ used for crawling, digging, or catching prey Clam
3 Groups of Mollusks • Gastropods • Bivalves • Cephalopods Biologists classify mollusks into groups based on physical traits (presence of shell, type of foot, or type of nervous system
Gastropods • Largest group of mollusks • They have either 1 outer shell or no shell • They can be herbivore or carnivore • They have aradula( flexible ribbon of tiny teeth to eat) • They move slowly with a foot • Examples are slugs and snails
Bivalves Mollusks with 2 shells held together by hinges and strong muscles • They are filter feeders (strain tiny organisms from the water) • Most are omnivore • The cilia on its gills moves food into the mouth • Some stay attached to hard surfaces, and some move slowly • Some can make pearls when sand gets stuck in between its mantle and shell • Examples are oysters, clams, scallops, and mussels
Cephalopods A mollusk whose foot is adapted to form tentacles around its mouth • Not all have external shells. But Nautilus does have shell • Only mollusk with a closed circulatory system • They are carnivores that use their muscular tentacles , radula and beak to cut up its food • They have suction cups (suckers) that can “taste” and sticks to its prey • They have large brains and great eyesight • They swim by jet propulsion by squeezing water out of their mantle through a tube called a siphon