1. Mollusks

2. A. Mollusks - soft bodied invertebrates that have a mantle and a muscular foot. 1. Mantle - tissue that covers a mollusk’s body. 2. Have lungs or gills that exchange carbon dioxide for oxygen. 3. Have a radula or a scratchy tongue-like organ to help them eat.

4. Three Groups of Mollusks

5. 1. Gastropods - most have a shell and are the largest group. a. Live in water or land b. Move by gliding their large muscular foot across a trail of mucus. c. Have a radula to help them get food. d. Snails, slugs, and conchs are examples.

6. 2. Bivalves - have two shell halves held together by a muscle. a. Are filter feeders that take food out of the water. b. Have gills that take oxygen out of the water. c. Have an open circulatory system where blood splashes over organs. d. Clams, oysters, and scallops are examples.

7. 3. Cephlapods - have no shell and are the most complex group. a. Developed foot is divided into tentacles with suckers. b. Have a closed circulatory system that contains blood vessels. c. Adapted for quick movement in the ocean. d. Octopuses, squids, and nautilus are examples.