Download Directed Reading Section: Arthropods 1. Arthropods and annelids

Directed Reading
SECTION: ARTHROPODS
1. Arthropods and annelids are both protostomes.
2. Arthropods have jointed appendages that extend from the body wall. The appendages of annelids are not
jointed.
3. The eight characteristics of arthropods are segmentation; jointed appendages; a distinct head; an exoskeleton;
respiration by gills, tracheae, or book lungs; excretion through Malpighian tubules; an open circulatory system;
and compound eyes (in some species).
4. In adult arthropods, body segments are fused to form three regions—the head, thorax, and abdomen. In some,
the thorax and head fuse to form a body region called the cephalothorax.
5. The majority of terrestrial arthropods respire through a network of fine tubes called tracheae. Air passes through
spiracles and into the tracheae. Book lungs are used by some groups.
6. Water and small dissolved particles in the blood move through Malpighian tubules and into the arthropod’s gut.
Metabolic wastes remain in the gut and eventually leave the body through the anus.
7. A compound eye is an eye made of thousands of individual visual units.
8. An arthropod’s exoskeleton prevents the arthropod from growing bigger. For this reason, they must molt. To
molt, arthropods shed their exoskeleton from time to time and form a new exoskeleton.
9. Hexapoda
10. Chelicerata
11. Chelicerata
12. Crustacea
13. Chelicerata
14. Myriapoda
15. Chelicerata
Active Reading
SECTION: ARTHROPODS
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An exoskeleton is a skeleton found outside an organism’s body.
It protects the organism from predators and helps prevent water loss.
It forms just before molting beneath the old exoskeleton.
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Quiz
SECTION: ARTHROPODS
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