| A | B |
|---|
| notochord | a flexible, rodlike structure that extends the length of the body |
| cartilage | tough, flexible material making up the skeletons or parts of skeletons of vertebrates |
| neural crest | a group of cells that develop from the nerve cord in vertebrates |
| fin | paddle-shaped structure on a fish or other aquatic animal that is used for balance, steering, and propulsion |
| scale | small, flat, plate-like structure near the surface of the skin |
| operculum | a movable flap that covers the gills and protects them |
| atrium | the chamber of the heart that receives blood from the body |
| ventricle | a chamber of the heart that pumps blood from the heart to the gills |
| nephron | a filtering unit within the kidney that helps to maintain the salt and water balance of the body and to remove cellular waste products from the blood |
| lateral line system | this enables fish to detect movement in the water and also helps to keep them upright and balanced |
| spawning | a process in which male and female fish release their gametes near each other in the water |
| swim bladder | a gas-filled space, like a balloon, found in bony fish that allows a fish to control its depth |
