Bottlenose dolphins are marine mammals known for their intelligence and social behaviors. They have streamlined bodies adapted for efficient movement and a distinctive snout.
Worldwide Presence
Bottlenose dolphins inhabit temperate and tropical waters globally, avoiding only the Arctic and Antarctic Circle regions. Their distribution is limited to surface water temperatures ranging from 10° to 32°C (50° to 90° F).
In the Atlantic Ocean, they are found from Nova Scotia to Patagonia and from Norway to southern South Africa. They are abundant along the United States’ coast, from Cape Cod through the Gulf of Mexico, and also extend into the Mediterranean and Black Seas.
In the Pacific Ocean, bottlenose dolphins range from northern Japan to Australia and from Southern California to Chile. They are also found offshore in the eastern tropical Pacific, reaching as far west as the Hawaiian Islands. Along the California coast, they have been observed as far north as Monterey during warmer periods.
The Indo-Pacific bottlenose dolphin (Tursiops aduncus) occupies the Indian Ocean, from Indonesia to Australia and South Africa, including the Red Sea, and extends into the tropical and subtropical western Pacific. This species resides over the continental shelf in shallow coastal waters. The common bottlenose dolphin (Tursiops truncatus) has a broader global distribution, found in coastal and oceanic habitats across most tropical to temperate oceans.
Preferred Environments
Bottlenose dolphins adapt to diverse marine and estuarine habitats, including warm temperate waters and occasionally rivers. Their habitat choices are influenced by factors like available resources, water depth, temperature, and seabed type. They are frequently found in coastal waters, including harbors, bays, gulfs, and estuaries, as well as shallow offshore areas over the continental shelf.
Scientists recognize two ecotypes of bottlenose dolphins: coastal and offshore populations, with distinct anatomical, physiological, behavioral, ecological, and genetic differences. Coastal dolphins form smaller groups, fewer than 20 individuals, and are seen in bays, tidal creeks, inlets, marshes, and rivers. They prefer shallow waters, less than 3 meters (9.8 feet) deep, and their smaller bodies and larger flippers are suited for maneuverability and heat dissipation in these warm, shallow environments. Their diet in these areas consists of fish and bottom-dwelling invertebrates.
Offshore bottlenose dolphins are larger and form larger groups, sometimes exceeding 100 individuals. These dolphins inhabit deeper waters of the continental shelf break and deeper waters. Their diet includes fish and squid, and they can dive to depths greater than 500 meters (1,600 feet) to find food. While coastal populations stay within limited home ranges close to shore, offshore populations range over larger areas.
Food availability is a key factor in bottlenose dolphin habitat choice. The presence and migration of their prey, correlating with seasonal water temperature changes, contribute to the dolphins’ movements. They thrive where fish, squid, and crustaceans are abundant, coordinating hunting techniques to capture schooling fish. Shallow waters also provide an advantage for detecting predators, contributing to the reproductive success of some female dolphins.