| A | B |
|---|
| acoelomate | A solid-bodied animal lacking a cavity between the gut and outer body wall |
| coelom | A body cavity completely lined with mesoderm |
| pharynx | An area in the vertebrate throat where air and food passages cross; in flatworms, the muscular tube that protrudes from the ventral side of the worm and ends in the mouth |
| flame cell | Specialized cell that filters and remove excess water from the body of a flat worm |
| ganglion | A cluster (functional group) of nerve cell bodies in a centralized nervous system |
| eyespot | Group of cells that can detect changes in amount of light in the enviroment |
| hermaphrodite | An individual that functions as both male and female in sexual reproduction by producing both sperm and eggs |
| fission | Form of asexual reproduction in which an organism split into two, and each half grows new parts to become a complete organism |
| scolex | Head of an adult tape worm |
| proglottid | One of the segments that nake up most of a tape worm's body |
| testis | The male reproductive organ, or gonad, in which sperm and reproductive hormones are produced |
| pseudocoelom | A body cavity consisting of a fluid-filled space between the endoderm and the mesoderm; characteristic of the nematodes |
| anus | Opening through which wastes leave the digestive tract |
| septum | A partition, or cross wall, that divides a structure, such as a fungal hypha, into compartments |
| seta | bristle attched to segments of many annelids |
| crop | In earthworms, part of the digestive system in which food can be stored |
| gizzard | In earthworms, part of the digestive system in which food is ground into smaller pieces |
| closed circulatory system | A type of internal transport in which blood is confined to vessels |
| gill | A localized extension of the body surface of many aquatic animals, specialized for gas exchange |
| nephridium | A tubular excretory structure found in many invertebrates |
| clitellum | band of thickened, specialized segments in annelids that secrete a mucous ring into which eggs and sperm are released |
| trochophore | Free-swimming larval stage of an aquatic mollusk |
| foot | muscular part of a mollusk |
| mantle | A heavy fold of tissue in mollusks that drapes over the visceral mass and may secrete a shell |
| shell | Structure in mollusks made by glands in the mantle that secrete calcium carbonate |
| visceral mass | Smooth muscle found in the walls of the digestive tract, bladder, arteries, and other internal organs |
| radula | Tongue-shaped structure used for feeding by snails and slugs |
| siphon | Tubelike structure through which water enters and leaves a mollusk's body |
| open circulatory system | An arrangement of internal transport in which blood bathes the organs directly and there is no distinction between blood and interstitial fluid |
