Common Name: Common bottlenose dolphin
Tursiops spp: The Tursiops genus has been split into two, T. truncatus and T. aduncus. The taxonomy of this genus is still not thoroughly clear, however due to considerable geographic variations, additional species may be recognised in the future.
General Description: Bottlenose dolphins have a large, robust head and trunk; the snout is clearly demarcated from the bulbous forehead by a sharp crease. The beak is usually short and stubby and the lower jaw protrudes conspicuously beyond the upper. The dorsal fin is moderately tall and falcate. The flippers are somewhat long and pointy at tips. The colouration is variable, but usually dark or slate grey on back, grading to white or pink on the belly. Adult dolphins may also have a white mark on the tip of the lower jaw. Calves have a slightly bluish colouration.
Size: Calves: Length of animals at birth is approximately 1-1.3 m. Adults: Adult dolphins are between 1.9-3.8 m, males tend to be slightly larger than the females. Maximum weight is around 650kg.
Appearance At Sea: This is the species of dolphin best known to the general public, as a result of exhibition in dolphinaria and films and television. Group sizes are mostly <20, however larger pods have been observed in offshore areas. They often school with other species including short-fin pilot whales and humpback whales.
Common bottlenose dolphins are found in small herds that sometimes gather into much larger schools. They often school with other species including Shortfin Pilot Whales.
There are a number of instances in which Bottlenose Dolphins have displayed mutual assistance and support. In cooperative defence, they may ram large sharks with their beaks or heads. The impact could be great enough to lift the fish out of the water.
Bottlenose Dolphins can reach speeds of 25 kilometres per hour.
Found In: Offshore and inshore waters of the northern Indian ocean.
Records from India: Majority of the records are from specimens caught in fishing nets. This species is not very common along the west coast of India. Most confirmed sightings are from the southeast coast, and from the Lakshadweep and Andaman Nicobar group of islands.
World Distribution: Found across coastal and continental shelf waters of tropics and temperate regions and associated with reef systems Also occur in enclosed or semi-enclosed seas. Distribution is restricted to lower altitudes.
Could Be Confused With: In areas where they overlap in distribution, common bottlenose dolphins can be confused with Indo-Pacific bottlenose dolphins, rough toothed dolphins and spotted dolphins.
Diagnostic Features at sea: Can be distinguished from Indo-Pacific bottlenose dolphins based on overall size, shape of head and beak and colouration. Ventral spotting is very rare, unlike Indo-Pacific bottlenose dolphins.
Stranded Specimens: Stranded individuals can best be identified based stubby beak and robust bodies. Teeth count is usually between 18-27 pairs in each jaw, teeth are stout and pointy and smooth.
Note: Bottlenose Dolphin recorded from India recently have been identified as Tursiops aduncus. This raises the possibility that previous records of Tursiops truncatus are misidentifications.
