| A | B |
|---|
| gill slits | paired openings used for breathing |
| endotherm | vertebrates with a constant body temperature |
| ectotherm | body temperature changes with environment |
| amphibian | ectothermic land and water animal |
| swim bladder | structure that allows a fish to go up or down in the water |
| reptile | an ectothermic animal with dry skin |
| tympanic membrane | structures used by frogs to hear |
| scales | hard, thin, overlapping plates used for protection |
| fins | fan-like steering structures in fish |
| amniotic egg | provides a complete environment for the embryo |
| Open Circulatory System | Blood is not always in vessels |
| Agnatha | The jawless fish |
| Closed Circulatory System | Blood stays within the heart and blood vessels |
| Osteichthyes | Bony Fish |
