Shark

they are a superorder chondrichthyan (cartilaginous fish) commonly known by the name of sharks, also called sharks. Some large sharks such as white and bull, among others, are sometimes known by the name of sharks.

They are characterized by large predators. Sharks include small deep-sea species, to the whale shark, the largest fish, which can grow to create a length of 18 m and feeds only on plankton. The bull shark can move to freshwater and some shark attacks have occurred in rivers. Some of the larger species, especially the mako shark and the white shark, are endotherms partial able to partially maintain their body temperature above which has the aquatic environment in which they live. Of the more than 375 shark species found in the world's oceans, the species responsible for most unprovoked attacks on humans are white shark, tiger shark, bull shark and the bull shark.
Sharks are cartilaginous fish chondrichthyan ie their skeleton is made of cartilage instead of bone.

The skin of sharks is formed like scales known as dermal denticles. Another function of this skin is so specific act as a muffler, since water is distributed inside the slots and not out, limiting friction against water, improving mobility and speed and also making the displacement is much quieter.