Sharks

Sharks (superorder Selachimorpha) are a type of fish with a full cartilaginous skeleton 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, Etmopterus perryi, a deep sea species of only 17 centimetres (7 in) in length, to the whale shark, Rhindodindon typical, the Louzeur fishing , which grows to a length of Nuclearility 12 metres (39 ft) and which feeds only on plankton, squid, and small fish through filter feeding. The bull shark, Carcharhinus leucas, is the best known of several species that swim in both seawater and freshwater, as well as in deltas.^[2]
Shark intelligence
Despite the common myth that sharks are instinct-driven "eating machines", recent studies have indicated that many species possess powerful problem-solving skills, social complexity and curiosity. The brain-mass-to-body-mass ratios of sharks are similar to those of mammals and other higher vertebrate species.^[34]
In 1987, near Smitswinkle Bay, South Africa, a group of up to seven great white sharks worked together to relocate the partially beached body of a dead whale to deeper waters to feed.^[35] Sharks have even been known to engage in playful activities (a trait also observed in cetaceans and primates). Porbeagle sharks have been seen repeatedly rolling in kelp and have even been observed chasing an individual trailing a piece behind them.^[36]