shark

The selacimorfos (Selachimorpha, the Greek selachos, sharks, and morph, shape) is a superorder of Chondrichthyes (cartilaginous fish) commonly known by the name of sharks, or so-called sharks.

Are characterized by large predators. The sharks range from small species of the deep sea, to the whale shark, the largest fish, which is believed can measure a length of 18 m and feeds only on plankton. The bull shark can move to fresh water and some shark attacks have occurred in rivers. Some of the larger species, including mako shark and great white sharks, are partial endotherms, partially able to maintain their body temperature above that found in the aquatic environment in which they live