| A | B |
|---|
| amniotic egg | in reptiles, th eleathery egg that provides a complete environment for the developing embryo |
| amphibian | ectothermic land and water animal |
| biological indicator | species that are sensitive to changes in the environment |
| cartilage | tough, flexible tissue |
| chordate | every vertebrate is also this |
| dorsal hollow nerve cord | a tubular bundle of nerves that lies above the notochord in a chordate animal |
| ectotherm | vertebrate animal whose internal body temperature changes with its environment |
| endoskeleton | internal skeleton |
| endotherm | vertebrate animal that maintains a constant body temperature |
| estivation | inactivity in hot temperatures |
| fin | fanlike steering structure in fish |
| fish | an ectothermic vertebrate whose gills, fins, and scales adapt it to living in water |
| gill slit | paired openings in the throat, exhanges carbon dioxide with water. |
| hibernation | inactivity in cold temperatures |
| notochord | dorsal structure that becomes the backbone in vertebrates |
| reptile | an ectotherm with dry skin |
| scale | hard, thin, overlapping plates that cover and protect a fish's body |
