| A | B |
|---|
| echinoderms | members of the phylum Echinodermata are invertebrates including sea stars, sand dollars, sea urchins, and sea cucumbers |
| pentaradial symmetry | a type of radial symmetry in which the body parts extend from the center along five spokes |
| ossicles | an endoskeleton composed of calcium carbonate plates which are attached to spines or spicules that protrude through the skin |
| water vascular system | a network of water-filled canals inside their body |
| tube-feet | many small moveable extensions of the water-vascular system which aid in movement, feeding, respiration, and excretion |
| class Crinoidea | called crinoids include sea lillies, and feather stars |
| class Ophiuroidea | 2000 species of basket stars and brittle stars |
| class Echinoidea | consists of about 900 species of sea urchins and sand dollars |
| test | a compact rigid endoskeleton where the internal organs are enclosed |
| class Holothuroidea | sea cucumbers, armless echinoderms that live on the sea bottom |
| class Asteroidea | sea stars or star fish |
| oral surface | the side of the body where the mouth is located |
| aboral surface | the side of the body that is opposite from the mouth |
| pedicellariae | numerous tiny pincers surrounding each spine in many star fish |
| madreporite | a sievelike plate on the aboral surface |
| stone cannal | a tube that connects the madreporite to the ring canal |
| ring canal | encircles that mouth |
| radial canal | another tube that extends from the ring canal to the end of each arm, which carry water to the hundreds of hollow tube feet |
| ampulla | a bulblike sac made up of the upper end of each expanded tube foot tube foot |
| cardiac stomach | where the sea star's mouth is connected by a short esophagus |
| pyloric stomach | the cardiac stomach transfers food here which connects to a pair of digestive glands in each arm |
| skin gills | hollow tubes that project from the coelom lining to the exterior where gas exchange and waste excretion take place by diffusion through the thin walls of the tube feet |
| nerve ring | what the nervous system is composed of and circles the mouth |
| radial nerve | the second part of the nervous system that runs from the nerve ring along the length of each arm |
| bipinnaria | free swimming larva |
| phylum Chordata | vertebrates or animals with backbones |
| subphylum Cephalochordata | contains about 2 dozen species of blade shaped animals known as lancets |
| atriopore | an opening where the water leaves |
| subphylum Urochordata | 2000 species are commonly called tunicates because their bodies are covered by a tough covering or tunic |
