The common bottlenose dolphin is the dolphin most people picture: grey above, paler below, with a short thick beak, a curved dorsal fin and a mouth shaped into a permanent smile. Adults are 2-4 meters (6.5-13 feet) long and weigh 150-650 kg (330-1,400 lbs). Dolphins living offshore in cooler water tend to be larger than those in warm coastal bays.
They have 72-104 small cone-shaped teeth, used to grip fish that are then swallowed whole. Their skin is smooth and rubbery and is replaced every two hours or so, which helps them slip through the water. A bottlenose dolphin can swim at more than 30 km/h (18 mph) in short bursts.
Bottlenose dolphins have large, complex brains and are considered among the most intelligent animals. They live 40-60 years, and females give birth to a single calf every three to six years after a 12-month pregnancy.
Common bottlenose dolphins live in temperate and tropical waters all around the world. Coastal populations stay in bays, estuaries, lagoons and harbours, and some follow the tide into rivers. Offshore populations live far out at sea along the continental shelf and around oceanic islands.
They are found from the Atlantic coast of the United States and the Mediterranean to the Indian Ocean, Australia and the Pacific coast of the Americas.
Bottlenose dolphins eat fish such as mullet, croaker, mackerel and herring, along with squid and shrimp. An adult eats 8-15 kg (18-33 lbs) a day.
Different groups have invented their own hunting tricks: driving fish onto mudbanks and sliding out to grab them, stirring up rings of mud to trap fish, smacking fish into the air with their tails, and in parts of Brazil working alongside human fishermen to herd mullet into nets.
Bottlenose dolphins live in loose groups of 2-15 near the coast and in larger groups of hundreds offshore. Group membership changes often, but mothers and calves and pairs of adult males form long-lasting bonds.
Each dolphin develops a unique signature whistle that works like a name. They use echolocation to find prey, ride the bow waves of boats, leap, surf and play with seaweed and other objects. They have been seen helping injured companions to the surface to breathe.
Tursiops truncatus belongs to the oceanic dolphin family Delphinidae. For many years all bottlenose dolphins were treated as one species, but the smaller Indo-Pacific bottlenose dolphin (Tursiops aduncus) is now recognised separately, and other populations are still being studied.
The IUCN lists the common bottlenose dolphin as Least Concern, with a worldwide population of at least 600,000. Some local populations, such as those in the Mediterranean and Black Sea, are at greater risk.
Threats include entanglement in fishing gear, pollution, disturbance from boats, underwater noise, and a history of capture for marine parks and aquariums.
