| A | B |
|---|
| behavior | the way a living thing acts |
| instinct | a behavior that an animal is born with and doesn't have to learn |
| reflex | a simple, automiatic behavior |
| stimulus | the cause of a behavior |
| response | a behavior caused by a stimulus |
| endangered | a population falling; in danger of becoming extinct |
| extinct | no longer existing |
| fossil | any mark or remains of a plant or animal that lived a long time ago |
| backbone | the main bone that runs along the middle of the back in some animals |
| molt | to shed an animal's outer covering |
| ecosystem | all living and nonliving things in an environment and how they interact |
| habitat | a place where an animal or plant lives |
| food chain | the energy flow through a community |
| predator | an animal that hunts and kills other animals for food |
| prey | the animals that predators hunt |
| food web | all the food chains in a community |
| pollution | anything harmful added to the air, land, or water |
| recycle | to use the same materials over and over again |
| exoskeleton | a hard outer covering that supports and protects some animals without a backbone |
