With two distinct dolphin species — the Amazon river dolphin and the Indo-Pacific humpback dolphin — sharing the common name pink dolphin, it isn’t surprising that people get confused between the two. But obviously both derive the common name from the fact that they are pink in color, but that’s where the similarity between them ends. In fact, the two species don’t even belong to the same genus. Sounds confusing? Things will become clear as you go through the facts about these dolphin species provided below.
Amazon River Dolphin Facts
❍ The Amazon river dolphin (Inia geoffrensis), also known as the pink dolphin or boto, is a freshwater dolphin endemic to South America. As of today, 3 subspecies of this river dolphin have been recorded — the Inia geoffrensis geoffrensis found in the Amazon and Araguaia/Tocantins basin, Inia geoffrensis boliviensis found in the Amazon basin, and Inia geoffrensis humboldtiana found in the Orinoco basin.
❍ The Amazon river dolphin is known as the pink dolphin owing to its pale pink color. This species is also known by several other names; prominent ones being Boto Vermelho, Boto Cor-de-Rosa, pink freshwater dolphin, and pink river dolphin. It was first described by the French zoologist, Henri Marie Ducrotay de Blainville, in 1817.
Amazon river dolphin
❍ On an average, these dolphins can grow on to attain a length of 2.5-3 meters, and weigh up to 200 lbs. The males in this species are relatively larger than the females. In terms of appearance, the pink dolphins do resemble the gray dolphins to a certain extent, but they are bigger in size as compared to the latter. In contrast to the other dolphins, which sport a dorsal fin, the pink dolphin has a hump on its back.
❍ The geographical range of this beautiful animal spans South American countries, like Brazil, Bolivia, Colombia, Ecuador, Peru, and Venezuela. The pink dolphin population flourishes in the Orinoco river, Amazon river, Araguaia river, and the Tocantins river, as well as the lakes in the vicinity.
Amazon river dolphin distribution
❍ The Amazon river system is spread over an area of 2,720,000 sq miles, which provides the pink dolphins a vast region to inhabit. When the tropical rainforests get flooded due to the increase in volume of the Amazon river water, these dolphins are also seen swimming among the trees.
❍ Unlike the dolphins found in oceans, these river dolphins have adapted themselves to the tropical rivers of South America. Their specially designed frontal teeth help them catch their prey, while their snout helps them burrow into narrow crevices whilst hunting. Their diet predominantly consists of crabs, crustaceans, catfish, and even small turtles and piranhas at times.
❍ Owing to their considerable size the Amazon river dolphins have very few natural predators; jaguars and caimans being the most prominent of the lot. The actual threat for this species comes from humans. The decline in Amazon river dolphin population can be mainly attributed to human activities, like overfishing, river pollution, and the resultant habitat loss.
❍ With a brain which is 40 percent larger than that of the humans, the pink dolphin is considered the most intelligent among the five river dolphin species. In fact, it is widely known for its curious nature and ability to get along with humans.
❍ The Amazon river dolphin is widely popular in South American folklore as the ‘Encantado‘ — the shapeshifting dolphin, which turns into a handsome young man and seduces women at night. It is also believed that killing this dolphin, or looking into its eyes, can bring bad luck to the person.
❍ The species was earlier enlisted as an Endangered Species by the International Union for Conservation of Nature (IUCN), but its status was eventually changed to Data Deficient species due to lack of data in 2011. This has come as a major blow for the environmentalists the world over, as it was the only river dolphin species which was found in abundance when the other four species were battling for their basic survival.
Indo-Pacific Humpback Dolphin Facts
❍ The Indo-Pacific humpback dolphin (Sousa chinensis chinensis) is a subspecies of the humpback dolphin found in the waters of Southeast Asia. It is a member of the Sousa genus of dolphins found along the coast of Africa, Asia, and Australia, typically characterized by their unique humps and elongated dorsal fins.
❍ Indo-Pacific humpback dolphins are popularly known as the pink dolphins due to their pinkish-white appearance, which can be attributed to their overdeveloped blood vessels. Other than the common name pink dolphin, it is also known as the Chinese white dolphin and Pacific humpback dolphin.
❍ The pinkish white skin is only seen in the Indo-Pacific humpback dolphin population which inhabit the waters of Southeast Asia. Their overdeveloped blood vessels act as an adaptation which comes handy when it comes to thermoregulation, and that explains why the population in colder regions is relatively more pink.
Indo-Pacific humpback dolphin
❍ At full-growth, the Indo-Pacific humpback dolphins attain a length of 2-3.5 meters and weigh anywhere between 330-510 lbs. Though it is a subspecies of the humpback dolphins, it differs from the Indian humpback and Atlantic humpback species to a certain extent; the most striking points of contrast being its pinkish white skin and relatively larger dorsal fin.
❍ The Indo-Pacific humpback dolphins were first sighted by English adventurer, Peter Mundy, in 1637. However, it was only in 1765 that the species was scientifically described by the Swedish explorer and naturalist, Pehr Osbeck.
❍ These dolphins seem to prefer the shallow coastal areas of this region, wherein the depth of the water seldom exceeds 10 meters. They are also found in the brackish water of the Pearl River estuary, mainly around the islands of Lantau and Peng Chau.
Indo-Pacific humpback dolphin distribution
❍ This dolphin species is primarily known to feed on fish which can be directly swallowed, but their specific dietary habits depend on their distribution. The population inhabiting the brackish waters of the Peal River estuary, for instance, is known to feed on estuarine species found in abundance in this area. While squids and crabs are usually avoided, they constitute a major portion of their diet in times of food scarcity.
❍ This humpback dolphin species shares its natural habitat with sharks and killer whales, which happen to be its natural predators. Other than these predatory species, the species is threatened by human activities, like overfishing, marine transportation, etc. Habitat loss caused as a result of pollution is also taking its toll on these dolphins.
❍ The Indo-Pacific humpback dolphin has been enlisted as a ‘Near Threatened’ species in the IUCN list, with the Pearl River Estuary alone housing around 1200-1300 individuals. Environmentalists though, argue that the population of this species is on decline, and add that its conservation status is a matter of debate as it relies heavily on estimates.
Though the two don’t belong to the same genus, or family for that matter, there is no denying the fact that they are marvels of nature. Dolphin tours are popular across the world, but pink dolphins are different and sighting them in the wild is an altogether different experience. It is sad that these dolphins, like several other species in the world, are fighting for their very existence. If some concrete conservation measures are not implemented, we will soon find them in the list of extinct animals.