Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha and are the sister group to the rays.
Speed: 31 mph (Maximum, Adult, In the Water, In Short Bursts)
Lifespan: 20 – 30 years
Scientific name: Selachimorpha
Phylum: Chordata
Higher classification: Sharks
Subclass: elasmobranchii
Size
Sharks come in all sizes. The largest is the whale shark, which has been known to get as large as 18 meters (60 feet). The smallest fits in your hand. And the great white shark is somewhere in the middle.
It is made up of tiny teeth-like structures called placoid scales, also known as dermal denticles. These scales point towards the tail and help to reduce friction from surrounding water when the shark swims. Each year worldwide there are ~ 10 deaths attributable to shark attacks compared with ~ 150 deaths worldwide caused by falling coconuts. More people each year are killed by elephants, crocodiles, bees, and wars and many other dangers that confront us, than by sharks do you ask yourself why there are tiny fish under them the fish do that to eat the shark's leftovers.