The bottlenose dolphin (Tursiops spp.) is one of the most well-known species of dolphin. There appear to be two main varieties; a smaller, inshore form and a larger, more robust form that lives mainly offshore. This stocky species has a torpedo-shaped body, a short beak and pointed flippers. They are usually dark grey on the back with paler grey flanks and a white or pinkish belly. The sickle-shaped dorsal fin is tall, and positioned centrally on the back; variations in the shape of the dorsal fin along with scars and other markings on the skin can help researchers to identify individuals. A social species, the bottlenose dolphin may live in groups of 100s of individuals. The bottlenose dolphin has a broad diet, preying on a range of fish and invertebrate species. Dolphins can rest one side of their brain at a time, allowing them to sleep whilst remaining conscious enough to surface and breathe.