the sharks

Amazing fact about sharks. let's read it.Sharks have been studied closely for more than 100 years, mainly because of their low likelihood of contracting disease. Fish with bones have a pretty high rate of growing tumors. For a long time, scientists believed that sharks were immune to cancer and tumors. So what makes sharks different? They don't have bones. Their skeleton is made up entirely of cartilage. This is one reason that shark teeth are collectible -- it's the only fossil you can find from dead sharks. Their cartilage dissolves over time, and nothing is left but the hard-enameled teeth. Many researchers think that this cartilage holds the secret to the cure for some human medical conditions -- namely cancer.that's all.

thank you,
from:animal book