| A | B |
|---|
| invertebrates | animals that lack a backbone |
| vertebrates | animals that possess a backbone |
| sponges | phylum Porifera |
| epidermis | an outer layer of cells designed to provide protection |
| mesenchyme | the jellylike substance that separates the epidermis from the inner cells in a sponge |
| collar cells | flagellated cells that push water through a sponge |
| amoebocytes | cells that move using psuedopods and perform different functions in different animals |
| radial symmetry | if any longitudinal cut through an organism's center creates two identical halves |
| spherical symmetry | if any cut that runs through an organism's center creates two identical halves |
| bilateral symmetry | if an organism can only be cut into two identical halves by a single longitudinal cut along its center which divides it into right and left halves |
| phylum Cnidaria | jellyfish, sea anemones and hydra |
| polyp | the sessile, tubular form of a cnidarian with a mouth and tentacles at one end and a basal disk at the other |
| medusa | a free-swimming cnidarian with a bell-shaped body and tentacles |
| nematocysts | small capsules that contain a toxin which in injected into prey or predators |
| testes | organs that produce sperm |
| ovaries | organs that produce eggs |
| anterior end | the end of the animal that contains its head |
| posterior end | the end of an animal that contains its tail |
| circulatory system | a sytem designed to transport food and other necessary substances throughout a creature's body |
| nervous system | a system of sensitive cells that respond to stimuli such as sound, touch and taste |
| ganglia | masses of nerve vell bodies |
| hermaphroditic | possessing both the male and the female reproductive organs |
| regeneration | the ability to regrow a missing part of the body |
| univalve | an organism with a single shell |
| bivalve | an organism with two shells |
| foot | a muscular organ that is used for locomotion and takes a variety of forms depending on the animal |
| visceral hump | a hump that contains a mollusk's heart, digestive and excretory organs |
| mantle | a sheath of tissue that encloses the vital organs of a mollusk, makes the mollusk's shell and performs respiration |
| shell | a tough, multilayered structure secreted by the mantle, generally used for protection, but sometimes for body support. |
