| A | B |
|---|
| anterior | toward the head end |
| bilateral | when divided down the middle plane the two halves are mirror images |
| radial | when divided along a central axis the two halves are roughly equal |
| asymmetry | having an irregular (unbalanced) body design |
| carnivore | an animal that eats other animals |
| cephalization | term meaning having a definite head |
| detritus feeder | an organism that eats dead or decaying material |
| division of labor | each body part has its own function |
| dorsal | toward the top of the animal |
| proximal | the body end of an appendage that is closest to the body |
| distal | the end of an appendage away from the body |
| caudal | toward the tail |
| filter feeder | an animal that strains food from water |
| herivore | an animal that eats plant material |
| omnivore | an animal that eats both plants and animals |
| invertebrate | an animal with no backbone |
| vertebrate | an animal having a backbone |
| larva | immature from of an animal before adulthood |
| metamorphosis | the process of change |
| parasite | an animal that feeds from a host |
| posterior | toward the rear |
| ventral | toward the belly or under side |
| sessile | staying permanent attached to neighboring rocks or other surfaces |
| locomotion | moving around from place to place |
| heterotroph | term referring to organisms that have to get food from an outside source |
| egg | female sex cell |
| sperm | male sex cell |
| development | series of stages from zygote to adult |
| zygote | a fertilized egg cell |
| blastula | hollow ball formed by a single layer of cells and filled with fluid |
| gastrula | a developmental stage when the blastula has folded inward yeilding two layers of cells |
| endoderm | the inner surface of the gastrula; forms the digestive system |
| ectoderm | the outer layer of the gastrula; forms the skin and nervous system |
| mesoderm | the "middle" layer of the gastrula; forms muscles, skeleton, circulatory system, and reproductive system. |
| endoskeleton | an internal skeleton |
| exoskeleton | an external skeleton or shell |
| protosomes | animals whose mouth is formed from the opening in the gastrula |
| deuterosomes | animals whose anus forms from the opening in the gastrula |
| coelom | a complete body cavity (surrounded by the mesoderm) |
| acoelomates | animals that lack a body cavity |
