| A | B |
|---|
| radial symmetry | Characterizing a body shaped like a pie or barrel, with many equal parts radiating outward like the spokes of a wheel; present in cnidarians and echinoderms |
| bilateral symmetry | Characterizing a body form with a central longitudinal plane that divides the body into two equal but opposite halves |
| cephalization | Concentration of sense organs and nerve cells in front of the body |
| coelom | A body cavity completely lined with mesoderm |
| intracellular digestion | Process in which food is digested inside cells |
| extracellular digestion | Process in which food is broken down outside the cells in a digestive tract |
| 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 |
| closed circulatory system | A type of internal transport in which blood is confined to vessels |
| hydrostatic skeleton | A skeletal system composed of fluid held under pressure in a closed body compartment; the main skeleton of most cnidarians, flatworms, nematodes, and annelids |
| exoskeleton | A hard encasement on the surface of an animal, such as the shells of mollusks or the cuticles of arthropods, that provides protection and points of attachment for muscles |
| external fertilization | Process in which food is broken down outside the cells in a digestive tract |
| internal fertilization | Process in which eggs are fertilized inside the female's body |
