Ganges River Dolphin
Platanistidae: River Dolphin Family
The 5 species in this family all inhabit rivers in South America and Asia. They look alike and are grouped as a family, but the resemblance may be more to do with evolutionary pressures of similar habitat than close relationship. All the river dolphins are small for cetaceans, with long slender beaks and prominent rounded foreheads. The rivers these dolphins inhabit are muddy and full of sediment, and visibility is poor; as a result they rely heavily on echolocation to find food and avoid obstacles, and their eyes have become much reduced.
Ganges River Dolphin
The large majority of dolphins live in saltwater marine habitats. However, there are at least seven species of dolphin that regularly visit or permanently live in the freshwater habitats of large rivers.
Because rivers often carry a lot of cloudy sediment, especially during times of heavy rain, visibility can be very poor. Indeed, these dolphins have very small deep-set eyes that lack lenses and are probably only useful for detecting light and dark. Ganges river dolphins emit clicks frequently and rely strongly on echolocation to find their way around. These dolphins also hunt for prey using echolocation and by probing in the mud on the river bottom using their sensitive snouts. It feeds mainly on fish and some shrimps and hunts in the evening and at night.
The Ganges river dolphins has a long, slender snout and a very low, ridge-like dorsal fin. The side, or pectoral, fins of this species have very square back edges.
The Ganges river dolphin has a beak, which can be as long as 18 in (46 cm), and has up to 120 teeth. Its forehead curves up steeply from the beak. An agile animal, it generally swims on its side and returns to the normal upright position to breathe. It can dive for a maximum of 3 minutes at a time, but usually remains underwater for about 45 seconds.
These dolphins may inhabit fast-flowing rivers, where the flow can be violent, especially during times of flood. This means that Ganges river dolphins have to be able to be swim 24 hours a day to avoid being washed away and injured.
The Ganges river dolphins are usually seen in pairs and may gather in groups of 6 or so to feed. They mate in autumn, and the calves are born the following summer after a gestation period of about 9 months.
Distribution: India: Ganges and Brahmaputra river systems.
Habitat: River habitats, from the foothills of the Himalayas to tidal limits.
Food: Fish, shrimp and other bottom-dwelling invertebrates.
Size: 2 - 3 m (6.5 - 10 ft); 51 - 89 kg (112 - 195 lb).
Maturity: 10 years.
Breeding: Single young born at a time.
Life span: 30 years.