| A | B |
|---|
| swim bladder | an internal, gas-filled organ that helps bony fish stabilize its body at different water depths |
| cartilage | firm, flexible connective tissue |
| closed circulatory system | blood moves only within a connected network of blood vessels |
| ectotherm | an animal whose body does not produce much internal heat |
| gill | organs that take in oxygen that is dissolved in water |
| free-living organism | an organism that does not live in or on other organisms |
| notochord | a flexible rod that supports a chordate's back |
| sexual reproduction | process in which two parents contribute genes to form a new individual |
| endotherm | an animal whose body controls and regulates its temperature by controlling the internal heat it produces |
