ITS–The Mahakam Dolphin (Orcaella brevirostris), locally called Pesut, is a freshwater dweller and found strictly in Kalimantans Mahakam River and its effluents. It was reported that this mammalian species was also found in Kumai Bay, Central Kalimantan and in saltwater areas starting from the Bay of Bengal to Papua.
Orcaella Brevirostris is gray-black or blue coloured. It has a rounded head and a protruding forehead, which are actually layers of fatty tissue. The mouth is located on the bottom of the head, enabling it to feed on fish, crabs and shrimp living on the bottom of the river. Its teeth can grasp tightly around its often slippery prey.
The species, which live in groups of up to six, usually come to the surface of water for 1-2,5 minutes before it submerges. The female Pesut carries its baby in its womb for nine months and needs about two hours to give birth.
As a mammal that spends its whole life in water, the Pesut has a thick layer of fat to keep itself warm. It is often hunted for its fat, which can be made into oil. In India, this fat is believed to be capable of curing rheumatism.
The species is highly intelligent and can be easily trained to perform acrobatic stunts.
Its population is currently unknown but it is suspected that its number has lately undergone a great decline. Some traditional fishermen see the species as an enemy because it reduces their catch of fish, but others believe that it leads them to schools of fish.