| A | B |
|---|
| chordate | the phylum whose members have a notochord, a nerve cord, and slits in their throat area at some point in their lives |
| notochord | a flexible rod that supports a chordate's back |
| cartilage | a connective tissue that is more flexible than bone and gives support to some parts of the body |
| vertebra | the bones that make up the backbone of an animal |
| ectotherm | an animal whose body does not produce much internal heat |
| endotherm | an animal whose body controls and regulates its temperature by controlling the internal heat it produces |
| fish | a vertebrate that lives in the water and has fins |
| swim bladder | an internal gas filled organ that helps a bony fish stabilize its body at different water depths |
| buoyant force | the force that water exerts upward on any underwater object |
| amphibian | an ectothermic vertebrate that spends its early life in water and its adulthood on land, returning to water to reproduce |
| atrium | each of the two upper chambers of the heart that receives blood that comes into the heart |
| ventricle | a lower chamber of the heart that pumps blood out to the lungs and body |
| habitat | the place where an organism lives and that provides the things the organism needs |
| reptile | an ectothermic vertebrate with lungs and scaly skin; lays eggs with tough leathery shells |
