| A | B |
|---|
| gill slits | paired openings used for breathing |
| endotherm | vertebrates with a constant body temperature |
| endoskeleton | the internal skeleton |
| nocturnal | inactivity at night |
| external fertilization | males swim over the eggs and release sperm |
| ectotherm | body temperature changes with environment |
| notochord | dorsal structure that becomes the backbone in vertebrates |
| amphibian | ectothermic land and water animal |
| swim bladder | structure that allows a fish to go up or down in the water |
| buoyancy | the ability of a liquid or gas to exert an upward force |
| reptile | an ectothermic animal with dry skin |
| skin and lungs | structures used by frogs to brethe |
| scales | hard, thin, overlapping plates used for protection |
| fins | fan-like steering structures in fish |
| ectotherms | species that are sensitive to changes in the environmental temperature |
| chordate | every vertebrate is also this |
| nerve cord | bundle of nerves above the notochord and/or backbone |
| hibernation | inactivity in winter |
| adaptatiion | makes an organism better able to survive its environment |
| fish | ectothermic vertebrae that lives entire life in water |
| cartilage | tough, flexible tissue not present in bony fish |
