2. Sharks (superorderSelachimorpha) are a type of fish with a full cartilaginousskeleton and a highly streamlined body. They respire with the use of five to seven gill slits. Sharks have a covering of dermal denticles that protect their skin from damage and parasites and improve fluid dynamics. They have several sets of replaceable teeth.[1] Sharks range in size from the small dwarf lanternshark, Etmopterusperryi, a deep sea species of only 17 centimetres (7 in) in length, to the whale shark, Rhincodontypus, the largest fish, which grows to a length of approximately 12 metres (39 ft) and which feeds only on plankton, squid, and small fish through filter feeding. The bull shark, Carcharhinusleucas, is the best known of several species that swim in both seawater and freshwater