| A | B |
|---|
| water vascular system | a system of fluid-filled tubes in an echinoderm's body |
| dorsal | back or spine side |
| posterior | away from the head |
| anterior | toward the head |
| ventral | front or belly side |
| antenna | an appendage that contains sense organs, usually found on the head of an arthropod |
| arthropod | a phylum of invertebrates that have hard segmentd body coverings and jointed legs |
| bilateral symmetry | body plan with two halves that are mirror images |
| bivalve | a mollusk that has two shells held together by hinges and strong muscles |
| carnivore | an animal that feeds on other animals |
| cephalopod | an ocean-dwelling mollusk whose foot is adapted as tentacles that surround its mouth |
| closed circulatory system | blood moves only within a connected network of blood vessels |
| commensalism | relationship between species in which one species is helped and the other is unaffected |
| consumer | an organism that feeds on other organisms |
| crustacean | an arthropod that has two or three body sections, five or more pairs of legs, and two pairs of antennae |
| decomposer | simple organisms that break down dead organisms and waste, returning important nutrients to the environment |
| exoskeleton | a firm, supportive covering on the outside of certain organisms |
| gastropod | a mollusk with a single shell or no shell |
| gill | organs that take in oxygen that is dissolved in water |
| herbivore | an animal that feeds only on plants |
| metamorphisis | a process in which an animal's body undergoes dramatic changes in form during its life cycle |
| mollusk | an invertebrate with a soft, unsegmented body; most are protected by a hard outer shell |
| molting | the casting off or shedding of an outer layer or covering and the formation of its replacement |
| mutualism | relationship between two species in which both benefit |
| omnivore | an animal that feeds on both plants and animal |
| open circulatory system | system in which the heart pumps blood into open spaces in the body and blood is not confined to blood vessels |
| producer | organism that makes its own food |
| radula | a flexible ribbon of tiny teeth in mollusks |
| tube feet | extensions of an echinoderm's water vascular system that stick out from the body and function in movement and obtaining food |
| endoskeleton | an internal skeleton |
