| A | B |
|---|
| dorsal structure that becomes the backbone | notochord |
| structure that later develops a brain at one end | dorsal hollow nerve cord |
| paired openings in the throat behind the mouth | gill slits |
| animal whose body temperature changes with the climate | ectotherm |
| animal whose body temperature stays the same in all climates | endotherm |
| tough, flexible tissue in the tips of human noses | cartilage |
| structure in which a reptile embryo develops | amniotic egg |
| fanlike structure fish used for steering, balance, and movement | fin |
| period of inactivity in the winter | hibernation |
| period of inactivity in the summer | estivation |
