Bottlenose dolphin, (genus Tursiops), also called bottle-nosed dolphin, any of three species of oceanic dolphins classified within the marine mammal family Delphinidae and characterized by a bottle-shaped snout. The common bottlenose dolphin (Tursiops truncatus), which is the most widely recognized dolphin species, is found worldwide in warm and temperate seas. In contrast, the Indian Ocean bottlenose dolphin (T. aduncus) inhabits continental shelf areas of the Indian Ocean and the waters fringing Southeast Asia, Indonesia, and Australia. The southern Australian bottlenose dolphin (T. australis), or Burrunan dolphin, which frequents the waters off Australia’s southern and southeastern shores, has the smallest geographic range.
Bottlenose dolphins reach an average length of 2.5–3 metres (8–10 feet) and weight of 135–300 kg (300–650 pounds). Males are generally larger than females. A familiar performer at marine shows, T. truncatus is known for its “built-in smile” formed by the curvature of its mouth. It has also become the subject of scientific studies because of its intelligence and its ability to communicate with its kind through sounds and ultrasonic pulses.
Bottlenose dolphins have the longest social memories of any nonhuman species. They have been shown to recognize the unique whistles of individual dolphins they once associated with some 20 years after becoming separated from them. Captive specimens have demonstrated the ability to recognize their reflections in several experiments, suggesting a degree of self-awareness. That capability has been observed only in higher primates and a few other animal species.