| A | B |
|---|
| vertebrate | animal with a backbone |
| chordates | members of the phylum Chordata; vertebrates |
| notochord | stiff, flexible rod that is replaced by a backbone |
| hollow nerve cord | in vertebrates, this is also known as the spinal cord |
| pharyngeal pouches | develop into the gills and other body parts |
| vertebrae | flexible column of bone; protect the spinal cord |
| spinal cord | nerve cord filled with fluid |
| cartilage | tough, flexible material that makes up the softer parts of a skeleton |
| endotherm | an animal that can use body heat from chemical reactions in the body's cells to maintain a constant temperature |
| ectotherm | an organism that needs sources of heat outside of the body |
| lateral line | row or rows of tiny sense organs that detect water vibrations |
| gill | respiratory organ that removes oxygen from the water and exchanges it for carbon dioxide in the blood |
| cartilaginous fishes | store oil in their livers to help them float |
| swim bladder | a gas filled sac that is used to control bouyancy; also calledd a gas bladder |
| lung | a sac-like organ that takes oxygen from the air and delivers it to the blood |
| amphibian | "double life" |
| tadpole | the aquatic larva of a frog or toad |
| metamorphosis | a phase in the life cycle of many animals during which a rapid change from the immature form to the adult organism takes place |
| ecological indicators | organisms that are sensitive to vhanges in their environment that are used by scientists to measure the health of the environment |
| vocal sac | thin walled sac of skin that surrounds the vocal cords |
| amniotic egg | type of egg that is surrounded by a membrane; holds in fluids and protects the embryo |
| albumen | provides water and protein to the embryo |
| yolk | provides the embryo with a rich source of food |
| allantois | stores the embryo's waste; passes oxygen to the embryo from the shell |
| turtles | spend most of their lives in the water |
| tortoises | spend most of their lives on land |
| frogs | amphibian with smooth, moist skin |
| toads | a type of frog; bumpier and drier skin |
| crocodiles | narrow head and pointed snout |
| alligators | broad head and a rounded snout |
