| A | B |
|---|
| herbivore | an organism that eats only plants |
| mantle | a membrane that surrounds the internal organs of the mollusk |
| radula | a tongue-like organ with rows of teeth |
| gill | respiratory structures in mollusks |
| open circulatory system | a system in which the blood is pumped out of vessels into open spaces surrounding the body organs |
| closed circulatory system | a system in which the blood is confined to vessels as it moves through the body; it efficiently transports oxygen and nutrients to cells |
| nephridium | invertebrate structure used to eliminate wastes from cellular processes |
| siphon | tubular organ that pumps water over the gills of most mollusks; can be used for locomotion if water is expelled forcefully |
| protostome | an animal with a mouth that develops from the opening in the gastrula |
| crop | sac in which food and soil are stored until they pass to the gizzard; found in earthworms and birds |
| gizzard | muscular sac in earthworms and birds that contains hard particles that grind soil and food before they pass into the intestine |
| seta | tiny bristle that digs into soil and anchors an earthworm as it moves forward |
| clitellum | thickened band of segments that produce a cocoon from which young earthworms hatch |
