| A | B |
|---|
| mammal | an animal with a backbone, hair or fur, and milk-producing glands to feed its young |
| density | the quantity of matter in a given unit of volume |
| sound waves | vibrations transmitted through substances in waves |
| language | a system of signs or sounds that refer to objects or ideas and that can be combined in different ways to produce different meanings. |
| echolocation | in certain animals, such as dolphins and bats, a system in which sound waves are sent out and their echoes interpreted to determine the direction and distance of objects. |
| life cycle | the series of changes an animal goes through in its life |
| pupa | the nonfeeding stage in the life cycle of some insects when their adult tissues are formed |
| egg | in animals, the female reproductive cell |
| adult | the stage of an organism’s life cycle in which it is fully grown and developed |
| caterpillar | the wormlike stage in the life cycle of a butterfly or moth |
