| A | B |
|---|
| mollusk | invertebrates with soft, unsegmented bodies that are often protected by hard outer shells |
| mantle | thin layer of tissue that covers the internal organs |
| kidneys | organs that remove the waste produced by animal's cells |
| gills | organs that remove oxygen from the water |
| radula | flexible ribbon of tiny teeth |
| gastropod | mollusks that have a single shell or no shell |
| bivalves | mollusks that have two shells held together by hinges and strong muscles |
| cephalopods | mollusks whose feet are adapted to form tentacles around their mouths |
| arthropod | invertebrate that has an external skeleton, a segmented body, and jointed attachments called appendages |
| invertebrate | no backbone |
| exoskeleton | outer skeleton; protects the animal and helps prevent evaporation of water |
| chitin | material that exoskeletons are made of |
| molting | process of shedding an outgrown exoskeleton |
| antenna | appendage on the head that contains sense organs |
| crustacean | arthropod with two or three body sections and usuallyhas three pairs of appendages for chewing |
| metamorphosis | process in which an animal's body undergoes dramatic changes in form during its life cycle |
| arachnid | an arthropod with only two body sections |
| abdomen | hind section that contains the reproductive organs and part of the digestive system |
| insect | arthropod with three body sections, six legs, one pair of antenna and usualy one or two pairs of wings |
| thorax | mid-section to which wings and legs are attached |
| complete metamorphosis | four dramatically different stages: egg. larva, pupa, adult |
| pupa | insect is enclosed in a protective covering and gradually changes from a larva to an adult |
| gradual metamorphosis | no distinctly different larval stage, resembles the adult version at all stages |
| nymph | resembles the adult insect |
| camouflage | protective coloration in which the insect blends into its surroundings |
| sound | produced by vibrations and usually used to attract mates |
| echinoderm | radial symmetrical invertebrate that lives on the ocean floor |
| endoskeleton | internal skeleton made of plates that contain calcium |
| water vascular system | internal fluid system consists of fluid filled tubes within the echinoderm's body |
