Characteristics and Facts About Habitat and Reproduction
The Indus river dolphin is a subspecies of the river dolphin which can only be found in the Indus River in Pakistan and India. It is the first cetacean that swims on its side ever discovered.
Until 1998, this dolphin was considered to be the same species with the Ganges River dolphin. Further studies proved that, in fact, these are two subspecies of the freshwater river dolphin. The Indus river dolphin, or Platanista gangetica minor, belongs to the genus Platanista along with its cousin, the subspecies Platanista gangetica. The latter lives in the Ganges river.
This dolphin swims on the side and has adapted to living in freshwaters of large rivers. The main characteristic of this dolphin is its long snout which becomes thicker towards the end. The teeth are visible even when the jaws are closed. The teeth of young individuals are one inch long and very sharp, and they undergo transformation at maturity, becoming square and fat.
Since this species has no crystalline lens in the eyes, individuals are essentially blind, relying entirely on echolocation for hunting and navigation. However, it is believed that the eyes can still distinguish between various intensities of light as well as establish direction. The tail and flippers are large in proportion to the body.
Sexual dimorphism is present, with females being slightly larger than males. Females also grow longer rostrums after reaching 150 cm total length, growing 20 extra centimeters compared to males. Females can measure 2.6 meters and males 2.2 meters.
These dolphins inhabit only the Indus River, which runs mostly through Pakistan. While, in the past, they occupied most of its 3,400 km length, nowadays they only live in small subpopulations occupying a fifth of the river. The preferred habitat is in waters which are deeper than one meter and have more than 700 square meters in sectional area.
The diet of these dolphins mainly consists of fish and crustaceans. Individuals hunt using echolocation only since they cannot rely on their eyesight. The species usually feed on prawns, catfish, carp and a wide range of freshwater crustaceans.
Females have a gestational period of about nine to 10 months, giving birth to calves between January and May. Calves usually do not stay with their mothers for more than a few months. Indus river dolphin individuals can live for more than 20 years, with the oldest known specimen being 28 years old.