Dolphins of the genus Sousa are commonly characterized by
a small dorsal fin arising from a distinct ridge, similar
to that of a humpback whale. These ridges may continue along
the tail stock of the animal.
Sousa teuszii is the Atlantic species of the hump-back dolphin,
residing along the west coast of tropical and sub tropical
Africa. The Indo-Pacific hump-backed dolphin, S. chinensis,
ranges from northern Australia and southern China, around
the coastal rim of the Indian Ocean, to the east coast of
southern Africa. Besides being isolated geographically, S.
chinensis typically has more teeth (29 to 38 per row) than
S. teuszii (26 to 31 per row).
Hump-backed dolphins that live east of Indonesia may lack
dorsal ridges altogether and are thus often confused with
bottlenose dolphins. They often share each others' company
and have similarly-shaped heads with well-defined beaks. The
two genera can be distinguished by the rostrum, which is generally
longer in Sousa. Also, the hump-backed dolphins' melons are
less pronounced. Their flippers are broadly attached at their
bases and rounded at the tips.
Most hump-backed dolphins are some shade of gray, varying
from a deep slate color in the Atlantic to almost white in
the waters of Malaysia and northern Australia. Many have a
speckled appearance. The population around Hong Kong is noted
for its distinctive pink coloration.
Sexual dimorphism is exhibited by the dolphins, with the
dorsal ridges exaggerated in males. Males are larger, up to
three meters in length and 285 kilograms.