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Sharks

Selachimorpha

Sharks are a diverse group of cartilaginous fishes (elasmobranchs) 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 (unlike rays). Modern sharks are classified in the clade Selachimorpha, the sister group to the rays. Sharks range in size from the dwarf lanternshark (Etmopterus perryi), which reaches about 16–21 cm total length, to the whale shark (Rhincodon typus), the largest fish in the world, commonly cited at up to ~12 m (39–40 ft). Sharks are found in all seas and occupy a wide range of habitats and depths. Most sharks are marine, but a small number can enter or live in brackish and freshwater, notably the bull shark (Carcharhinus leucas), which is recorded in both salt and fresh water, and some river sharks (genus Glyphis) that use estuarine and freshwater habitats.

Sharks are a diverse group of cartilaginous fishes (elasmobranchs) 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 (unlike rays). Modern sharks are classified in the clade Selachimorpha, the sister group to the rays. Sharks range in size from the dwarf lanternshark (Etmopterus perryi), which reaches about 16–21 cm total length, to the whale shark (Rhincodon typus), the largest fish in the world, commonly cited at up to ~12 m (39–40 ft). Sharks are found in all seas and occupy a wide range of habitats and depths. Most sharks are marine, but a small number can enter or live in brackish and freshwater, notably the bull shark (Carcharhinus leucas), which is recorded in both salt and fresh water, and some river sharks (genus Glyphis) that use estuarine and freshwater habitats.