2.) Vertebrates have a backbone, an endoskeleton, or skeleton on the inside of the body, a large brain in a skull, a large brain in a skull, an advanced nervous system. A complex heart and circulatory system, a special kind of outer covering, one or two pairs of appendages.

3.) The five classes of a vertebrate are the fish, amphibian, reptile, bird, and mammal classes.

4.) Lampreys are parasites. They have a circular mouth with teeth on their tongues, which they use to attach themselves to another fish's body. When they attach to the fishes(host) they scrap away at the skin with their large teeth and a strong, rasping tongue. They then suck up the tissues and the body fluids of the fish(host). They are not true fishes because they have no bones what so ever. They are the only vertebrates that do not have backbone as adults.

5.) Sharks are not true fish because they do not have scales or bones in their skeleton. The also do not have a flap of skin covering their gills as some other fishes do. Sharks just have five to seven rows of slits.

6.) Cartilage is a tough tissue that bends easily.

23.) Birds can fly because the birds body is light because of the hollow and light bones. Birds also have large and powerful breast muscles to move their wings in flight.

21.) The protection given to an egg is one example of why the vertebrates are the most successful of all animals.

26.) Birds lay eggs because if the held them they would be to heavy to fly.

18.) Factors that make it possible for reptiles to live on land are internal fertilization and a protected egg.

Some common words found in the essay are:
, highly developed, chambered heart, internal fertilization, highly developed brain, true fish, heart warm-blooded, developed brain, heart cold-blooded, two-chambered heart, shape beak, brain skull,
Approximate Word count = 863
Approximate Pages = 3 (250 words per page double spaced)