Chapter 2 Section 1 Animals Mollusks Chapter 2 Section 1 Animals

What are Mollusks? Invertebrates Soft unsegmented bodies Often protected with hard shells Mantle Thin layer of tissue protecting organs Produces the shell

What are Mollusks? Move with a muscular foot Live everywhere Adapted for variety of uses Live everywhere Water, mountains, trees, oceans, land Bilateral symmetry

What are Mollusks? Internal organs all located in one area Kidneys Filter wastes Gills Remove oxygen from water Radula Flexible ribbon of teeth

Evidence of Early Mollusks Lived in Earth’s oceans 540 million years ago Evidence in limestone rocks Layers of broken shells fell to ocean floor Chemical reaction caused cementation Some shells didn’t break and were preserved in the rock

Snails and their Relatives Gastropod Stomach foot Shells Single Coiled None

Snails and their Relatives Habitat Anywhere Herbivore Carnivore Scavenger Defense Curl up in shell and close trapdoor

Two Shelled Mollusks Bivalves Two shells Held together by hinges do not have radula Filter feeders Use gills to capture food as they breath

Two Shelled Mollusks Found in watery environments Stay put or move slowly Oysters and mussels attach to a surface Clams dig into the sand Scallops clap their shells together to “swim”

Two Shelled Mollusks Grit lodged in a bivalve cause an irritation Mantle coats the grit Becomes covered in a pearly coat pearls

Mollusks with Tentacles Cephalopod Octopus Cuttlefish Nautiluses squid

Mollusks with Tentacles Shell Nautilus external shell Squid and cuttlefish internal shell Octopus no shell Obtain food Capture with tentacles Keen sense of touch and taste

Mollusks with Tentacles Large eyes Excellent vision Large brain and complex nervous system Live in the oceans only