| A | B |
|---|
| mollusks | soft-bodied invertebrates that usually have shells |
| invertebrate | animal without a backbone |
| appendages | structures that grow out from the body |
| radial symmetry | body parts arranged a central point |
| arthropods | invertebrates with jointed legs |
| metamorphosis | change in form some animals go through as they develop and mature |
| polyp | body plan that is shaped like a tube or vase |
| echinoderms | spiny-skinned invertebrates that live on the ocean bottom |
| medusa | body plan that is bell-shaped |
| mantle | thin layer of tissue that secretes a mollusk's shell |
| vertebrate | an animal with a backbone |
| open circulatory system | system in which blood is not in vessels but surrounding organs |
| gills | organs that exchange oxygen and carbon dioxide with water |
| radula | tongue-like organ in mollusks that works like a file |
| sessile | remaining attached to one place |
| bilateral symmetry | body parts are mirror images of each other |
| free-living | describing an organism that does not depend on another for food or a place to live |
| metamorphosis | change in body form some animals go through as they mature |
| exoskeleton | protective outer covering on arthropods |
| mollusks | soft-bodied invertebrate usually with a shell |
| closed circulatory system | system in which blood is contained in vessels |
