Sharks

how would you like to be swallowed by this guy?

There are more than 350 different kinds of sharks, and they range in size between 9 in. and 45 ft. 

Sharks have skeletons of cartilage, which is lighter and more  flexible than bones. Sharks' scales are called denticles, and are like sharp teeth and are rough and jagged - they feel like sandpaper. They have five different kinds of fins; caudal, anal, dorsal, pelvic, and pectoral:

Sound travels faster through water than air, hence the shark uses sound to locate prey. However, they use their eyes as well, though not as much. A shark's sense of smell is amazing, they can smell blood from about a mile away.

There are many rows of teeth in a shark's mouth. The front teeth are easily lost, then are replaced by new ones moving up from behind. 

Don't worry, sharks don't mainly prey on humans, in fact, if a shark attacks a human, it's almost always an accident. For instance, If a shark is really hungry and sees you moving, it might mistake you for a seal, but that usually never happens. All that stuff on movies about people being attacked by sharks are all over exaggerations. Another time that a shark might attack you is if it is trying to check you out. Sharks have nerves in their teeth, and they literally bite something to see what it is.