1. Introduction to the Anthropods 28-1

2. Exoskeleton External skeleton; tough external covering that protects and supports the body of many invertebrates.

3. Chitin Complex carbohydrate that makes up walls of fungi; also found in the external skeletons of arthropods.

4. Appendage Structure, such as a leg or antenna, that extends from the body wall.

5. Tracheal Tube One of many branching, air-filled tubes that extend throughout the bodies of many terrestrial arthropods.

6. Spiracle Small opening located along the side of the body through which air enters and leaves the body of many terrestrial arthropods.

7. Book Lung Organ that has layers of respiratory tissue that is used by some terrestrial arthropods for the exchange of gases.

8. Malpighian Tubule Saclike organ in most terrestrial arthropods that extracts wastes from the blood, adding them to feces that move through the gut.

9. Molting Process in which an arthropod sheds its exoskeleton and manufactures a larger one to take its place.