Classification: 

There have recently been changes to the number of species in this genus. In addition to the Atlantic humpback dolphin (Sousa teuszii), three species are now recognised; Sousa chinensis (Indo-Pacific humpback dolphin) – found from the east coast of India, through the Indo-Malay archipelago and east towards Australia; Sousa plumbea (Indian Ocean humpback dolphin) – found from South Africa to India; and Sousa sahulensis (Australian humpback dolphin) - found in northern Australia. 

 

 

Appearance: 

As suggested by the name, in many parts of their range the Indo-Pacific humpback dolphin and the Indian Ocean humpback dolphin have a distinct hump at the base of the dorsal fin.

Those in the easterly reaches of the species' distribution, lack this defining characteristic.

The Indo-Pacific humpback dolphin is a medium sized, robust dolphin with a rounded melon that slopes down to the beak.

The flippers are broad and rounded, and the beak is long and narrow. There is substantial morphological variation among differing species and populations, and colouration of these species ranges from white to pink to dark grey.

In the western portion of their range (now classified as Indian Ocean humpback dolphins), calves are born a light grey colour and darken with age. Calves are born a dark grey and lighten with age.

This transition from dark to light colouration results in the animals going through various stages of having dark spots and speckles around the body, all of which fade with age.

 

 

Behaviour: 

Humpback dolphins are coastal animals, venturing quite far landward into estuaries and mangroves.

Their inshore habitats are often turbid waters and thus sound production and reception are crucial for navigation and social contact.

In addition to their high frequency echolocation clicks, they are highly vocal, producing whistles and screams singly or in sequences and of varying lengths.

They are not known to bowride very often, but they do breach, lobtail, and even somersault on occasion.

They may also be seen sometimes swimming on one side while waving a flipper in the air.

They are generally slow swimmers but sometimes will chase each other around in circles at high speed; researchers suggest this may be courtship behaviour.

The average life-span of a humpback dolphin is thought to be approximately 40 years of age.