Fossils of ancient relatives date to the late Oligocene. It is pink in color and can grow to be up to 8 feet long. Fossil Platanistoidea showed a diversity of cochlea shapes, though Platanista was unusual in that it developed flatter spirals with larger gaps between them. The oldest known Ganges river dolphin was a 30 year old male1. The Irrawaddy dolphin ( Orcaella brevirostris) is a euryhaline species of oceanic dolphin found in scattered subpopulations near sea coasts and in estuaries and rivers in parts of the Bay of Bengal and Southeast Asia. You can change your preferences at any time., The Ganges river dolphin relies so heavily on echolocation that it has effectively become blind Zahangir Alom/ Marine Mammal Commission/ National Oceanic and Atmospheric Administration/ Wikimedia Commons. River dolphins are relatively small compared to other dolphins, having evolved to survive in warm, shallow water and strong river currents. This dolphin has a shy, quiet and rather passive behavior. River dolphin | Types & Facts | Britannica Ganges River Dolphin | Freshwater Dolphin | Species | WWF Pollution. Indus river dolphins are also known as the blind dolphins because over millions of years they have lost the use of their eyes. [57], Amazon river dolphins, known by the natives as the boto, encantados or toninas, are very prevalent in the mythology of the native South Americans. Irrigation has lowered water levels throughout both subspecies' ranges. PLoS ONE. [19][31] Hence, they are seen as bioindicators for the health of river systems. Without them, the populations of these animals would increase, and their predators wouldnt have as much to eat. This survey concentrated on the 1,044km stretch of dolphin-inhabited Brahmaputra River system, primarily in Assam of North East India. This species is functionally blind, and therefore relies heavily on echolocation to navigate and hunt4, 16. Their range extends from the Himalayan foothills to the Ganges Delta, across the countries of Nepal, India and Bangladesh. [35]:4146 Industrial and residential waste flowed into the Yangtze. In some places, like in the Kukurmara area of Kulsi River, for example, the dolphins are a tourist attraction due to protection by local communities. In river dolphins, and other cetaceans, there is no great difference between the outer and inner environments. For example, near the mouth of the Yangtze, the baiji was a princess that had lost her parents and had lived with her stepfather, whom she had longed to get away from. This dolphin usually swims with a fin touching the riverbed to feel the sediments since animals hide there. Distinctive characteristics. The Ganges river dolphin is found only within the freshwater river systems of the Ganges-Brahmaputra-Meghna and Karnaphuli-Sangu river systems of Bangladesh and India, while the recently described Indus river dolphin lives in the Indus river system of Pakistan. Ganges river dolphin | mammal | Britannica Environmental Toxicology and Chemistry, 18(7), 1511-1520. [29], As of 2022, the IUCN Red List of mammals lists both South Asian river dolphins as endangered. These marine mammals were found globally and occupied many of the same habitats as today's toothed whales, which belong to the delphinoid group. A male Amazon river dolphin can grow to over 2.4 metres (8 feet) and 160 kg (350 pounds); females are slightly smaller. [22][29]:203427[30][31] They are so dependent on echolocation that they can survive even if they are blind. An adult has a length between 2 and 2.2 meters, and it has an approximate weight of 51-89 kilograms. South Asian river dolphins were traditionally considered to be one species, Platanista gangetica, with the Ganges and Indus River populations being subspecies (P. g. gangetica and P. g. minor, respectively). Herald, E. S., Brownell, J. R. L., Frye, F. L., Morris, E. J., Evans, W., E., & Scott, A. [5][6] The results of these studies were criticized for their small sample sizes and the absence of statistical analyses; by the late 1990s, the two populations were again considered to be two subspecies of a single species. It is found throughout much of the Amazon and Orinoco river basins in Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, and Venezuela. They all have female-biased sexual dimorphism apart from Amazon river dolphin, with the females being larger than the males. These dolphins prey mainly on fish and shrimp and hunt them throughout the water column. [9] The researchers wanted to find out whether this is because the dolphins have had to adapt their echolocation to deal with the relatively shallow and turbid water in which they live, or they shared their peculiar ear shape with their now-extinct relatives. South Asian river dolphins reach sexual maturity at around ten years, though males may not reach their adult size until 20 years. [20], River dolphins have a torpedo shaped body with a flexible neck, limbs modified into flippers, non-existent external ear flaps, a tail fin, and a small bulbous head. It is probably a semi-gregarious and territorial animal since sometimes it chases other dolphins aggressively. [21][22] River dolphins are polygynous, meaning male river dolphins typically mate with multiple females every year, but females only mate every two to three years. The pools are not very large, only kidney shaped tanks with dimensions of 82 feet (25m) arc 23 feet (7.0m) width and 11 feet (3.4m) depth, 33 feet (10m) diameter, 6.6 feet (2.0m) deep and 39 feet (12m) diameter, 11 feet (3.4m) deep, and are not capable of holding many baijis at one time. [35]:3132,3738[36], As China developed economically, pressure on the baiji river dolphin grew significantly. Several hundred were captured between the 1950s and 1970s, and were distributed in dolphinariums throughout the US, Europe, and Japan. The pink colouration of jellyfish is due to their early April breeding season, which causes an increase in their hormones. Until recently, the South Asian river dolphin consisted of two sub-species, the Ganges river dolphin and the Indus river dolphin. He was estimated to be around 40 years old when he died in October 2020. The Araguaian boto (I. araguaiaensis), which is physically similar to the Amazon river dolphin, was classified as a separate species in 2014 on the basis of its distinct DNA. River dolphins are slow swimmers in comparison to oceanic dolphins, which can travel at speeds up to 35 miles per hour (56km/h); the tucuxi can only travel at about 14 miles per hour (23km/h). Mahseer fish (Family Cyprinidae). If a dolphin has a lot of air in its lungs and a thick layer of blubber, it will be more likely to float. Lower Ganges in Lakshmipur, Bangladesh. The Bolivian river dolphin (I. boliviensis), native to a few remote streams in the Bolivian Amazon, is slightly smaller than the Amazon river dolphin, and its skin is coloured grayish pink. Its eye lacks a lens, and the dolphin is sometimes referred to as being blind, although its eyes do seem to function as a direction-finding device. Smith, B. D. (1993). Now dams and barrages restrict dolphin movement, but in the past during the monsoon season, the dolphins would have moved upstream into smaller rivers, and then back downstream to larger river channels in the low water winter season4. Adults can be nearly 3 metres (10 feet) long. This survey concentrated on the 1,044km stretch of dolphin-inhabited Brahmaputra River system, primarily in Assam of North East India. The book by the same name, published in 1990, included pictures of a captive specimen, a male named Qi Qi () that lived in the Wuhan Institute of Hydrobiology dolphinarium from 1980 to July 14, 2002. Family: Platanistidae Their leaps out of the water are related to reactions to aggressions or external disturbances. Douglas Adams and Mark Carwardine documented their encounters with the endangered animals on their conservation travels for the BBC programme Last Chance to See. On the other hand, if it is deep in the water, it will be more likely to sink. Dr Travis Park, a researcher at the Museum, was involved in the study that compared the inner ear structure of the dolphin to it extinct fossil relatives. The young are gray. Living in murky river waters, their eyes are tiny and lensless. [56], In Chinese mythology, the baiji has many origin stories. The Ganges River dolphin measures 1.5 - 2.5 m (4.9 - 8.2 ft) in length and weighs up to 90 kg (200 lb). [14] Courtship and mating behaviour for the Ganges species has been documented from March to May, when the water level is lower, and involves multiple males chasing one female and ends with one of the males earning the right to mate. The Indus river dolphin (Platanista minor), also known as the bhulan in Urdu and Sindhi, is a species of toothed whale in the family Platanistidae.It is endemic to the Indus River Basin of Pakistan and northwestern India.This dolphin was the first discovered side-swimming cetacean. The Gangetic dolphins are a very unique species of dolphin. The Teotnio rapids between Bolivia and Brazil separate the two species, and DNA studies suggest that neither competition nor interbreeding has occurred between the Bolivian river dolphin and the boto for many tens (or possibly hundreds) of thousands of years. The body has a dark gray or brown color, with a lighter color in the ventral area. [13] Its probable eventual IUCN status is vulnerable or worse. (1969). Pale blue-gray above and lighter below, it grew to 2.4 metres (8 feet). Let us know if you have suggestions to improve this article (requires login). Only very small numbers of dolphins (<100) are present in Nepal5. [34] They have both rod and cone cells, meaning they can see in both dim and bright light. Full report: https://www.iucn.org/downloads/brahmaputra_river_dolphins___psf_final_report.pdf. This means they can turn their head without actually moving their entire body. The Ganges River dolphin mates throughout the year and not in any specific season. The ancestors of river dolphins were marine dolphins that invaded freshwater environments during high sea levels occurring near the end of the Miocene Epoch (23 million to 5.3 million years ago). The toothed whales, which includes all dolphins as well as some whales such as the sperm whale and beluga, are the most successful marine mammals currently swimming the oceans. The largest numbers of dolphins documented are in the main stem of the Ganges River in India and the Brahmaputra River in Bangladesh6. Shamans often intervene in these situations. Kelkar, N., Krishnaswamy, J., Choudhary, S., & Sutaria, D. (2010). 'Even within this group, the Ganges river dolphin is an outlier. Its most common practice is finding a school of fish near the surface and drag them to the bottom to eat them. For many Hindus, even dirty water is still holy and they will take a dip in it as a way to cleanse themselves. To protect them it is vital that we involve local river communities. Blubber can help with buoyancy, protection from predators (they would have a hard time getting through a thick layer of fat), energy for leaner times, and insulation from harsh climates. Surveys to estimate abundance or the number of the Ganges river dolphins have been conducted in many places in India, Nepal and the Sundarbans of Bangladesh. [29]:447454, Development and agriculture have had devastating impacts on the habitats on river dolphins. The Ganges river dolphin ( Platanista gangetica) is a species of toothed whale classified in the family Platanistidae. This results in the amazing natural rainbow colouring in the skins of dolphins. To be successful, its important to set boundaries and stick to a schedule. Hindus also sprinkle a little water on their heads as a way to receive a blessing. Review of reproduction in Platanistid dolphins. Gobio. You also need to be proactive about communicating with your team and your boss. [29]:481505, River dolphins are not thought to have a sense of taste, as their taste buds are atrophied or missing altogether. They do not have the iconic spout, as this only forms when the warm air exhaled from the lungs meets cold external air, which does not occur in their tropical habitats. [14] Indus dolphins have more teeth than Ganges dolphins, averaging 33.2 teeth in the upper jaw and the 32.9 in the lower jaw, as compared to 28.4 in the upper jaw and 29.4 in the lower. The Amazon river dolphin is a freshwater dolphin that is found throughout much of the Amazon and Orinoco river basins. Not much is known about the mating and reproduction of Ganges river dolphins except that they breed year-round and most births are thought to occur between October-March17. Ganges River dolphins occupy freshwater river systems in southern Asia. Although the International Union for Conservation of Nature and Natural Resources (IUCN) considers the species to be critically endangered, it is now widely believed to be functionally extinct. [14], South Asian river dolphins appear to be active throughout the day. [18] Outflows of freshwater into the Bay of Bengal have allowed them to swim along the coast, and there is at least one record of an individual entering the Budhabalanga River, around 300km (190mi) southwest of the Ganges Delta. They are most commonly found in stream pools, meanders, and confluences, and around river islands and shoals, which produce relatively stable waters. 1196 Gland 'It is one of just two surviving species of this once massive group that were the dominant toothed whales up until about 12-15 million years ago, when more modern dolphins appeared on the scene and eventually replaced them.'. the Ganges river dolphin (Platanista gangetica) and the Indus river dolphin (P. minor), which are classified as endangered species, and the Atlantic humpbacked dolphin (Sousa teuszii), which is classified as critically endangered. They largely navigate by echo-location or sonar, which means that they are at a disadvantage when it comes to avoiding predators or finding food. River dolphin - Wikipedia Amazon River dolphin - Whale & Dolphin Conservation USA [22], River dolphins have two flippers and a tail fin. Skin Coloration. ", https://en.wikipedia.org/w/index.php?title=River_dolphin&oldid=1158085231, River dolphins are not a taxon, they are an informal grouping of the infraorder, This page was last edited on 1 June 2023, at 22:19. Their neck joints give them great flexibility. Omissions? Prawn. [46][47][48][39][49][50][51][52] The local fishermen overfish, and when the Amazon river dolphins remove the commercialized fish from the nets and lines, it damages the equipment and the capture and causes a negative reaction from the local fishermen. However, some dolphins have preferences between different kinds of fish, indicating some sort of attachment to taste. The Ganges River Dolphin is found mainly in the Ganges and Brahmaputra river systems in India and Bangladesh. Its also easy to get overwhelmed by all of the work that needs to be done. A call for mobilisation to the entire Union. The total of all dolphin counts throughout the range is approximately 5,000 individuals. The riverbed was dredged and reinforced with concrete in many locations. The maximum speed that this dolphin reaches when swimming in its natural habitat is 27 kilometers per hour. In 1853, Richard Owen described a specimen from the Indus and considered it to be the same species as the Ganges river dolphin, but a smaller form. Species: Platanista gangetica. [3], Based on differences in skull and vertebrae structure, blood proteins, and lipids, scientists declared them to be separate species in the 1970s. Shrimp. [18][30] Two assessments in 2014 and 2015 estimated populations of 3,500 for the Ganges river dolphin and 1,500 for the Indus river dolphin. The ear is acoustically isolated from the skull by air-filled sinus pockets, which allows for greater directional hearing underwater. South Asian river dolphins are toothed whales in the genus Platanista, which inhabit fresh water habitats in the northern Indian subcontinent. [18] The tucuxi is currently classified as an oceanic dolphin (Delphinidae). [23], River dolphins are typically seen alone or in groups of up to 10 individuals, though enough natural resources may attract up to 30 dolphins. River dolphins are not very widely distributed; they are all restricted to certain rivers or deltas. [20], South Asian river dolphins inhabit major river channels during the dry season and travel to smaller tributaries for the monsoon. It occurs only in fresh water, in Bangladesh and India , where the rivers flow slowly through the plains, as well as in Nepal, where the dolphin can be found in relatively clear water and rapids. Instead, they spend much of their time at river bottoms, probing with sensitive snouts for mud-loving fish and crustaceans. In India and Nepal they are known as the Ganges river dolphins or susu and in Bangladesh they're called shushuk. The dolphin is said to be one of the creatures which heralded the goddess' descent from the heavens, and Ganga's mount, the Makara, is sometimes depicted as a dolphin. The Ganges river dolphin is found only within the freshwater river systems of the Ganges-Brahmaputra-Meghna and Karnaphuli-Sangu river systems of Bangladesh and India, while the recently described Indus river dolphin lives in the Indus river system of Pakistan. They also affect river habitats by reducing water availability and habitat quality, and blocking passage for migratory fish11, 12. Male river dolphins typically mate with multiple females every year, but females only mate every two to three years. Such species are considered facultative freshwater cetaceans as they can use both marine and freshwater environments. [4] Our editors will review what youve submitted and determine whether to revise the article. The fear of this is so great among people who live near the Amazon River that both children and adults are terrified of going near the water between dusk and dawn, or entering water alone. Genetic and morphological evidence led to their being described as separate species in 2021. Platanistidae fossils have been found in Miocene deposits in Europe and North America. ), Biology and Conservation of Freshwater Cetaceans in Asia (pp. The Ganges river dolphin is known as the Tiger of the Ganges for the role it plays as a top predator, and because it is an ecosystem indicator species much like a tiger is in a forest. The IUCN classified the Atlantic humpback dolphin as a vulnerable species between 2008 and 2017 but reclassified the species as critically endangered in 2017 after studies suggested that fewer than 3,000 remained in the wild. The baiji, or Chinese river dolphin (Lipotes vexillifer), was native to Chinas Yangtze River. It is a relatively large interval that, together with the late maturation, produce a low natality rate that does not contribute to increasing the number of individuals in the wild. External links. The people of the coastal area in Bangladesh, IUCN has been working with UNHCR since 2018 to mitigate human-elephant conflict (HEC) around the, The first-ever knowledge forum on the Meghna river basin, shared by Bangladesh and India, concluded, Headquarters River dolphins - Whale & Dolphin Conservation USA [19] Fragmentation of populations makes these dolphins more vulnerable to inbreeding. Ganges River Dolphin: An Overview of Biology, Ecology, and Conservation During high water seasons created by monsoon rains, Ganges river dolphins are able to spread out and live in seasonal tributaries and lakes as well as the main river channels. These dolphins do not have many predators in their habitat, so most of their threats are anthropogenic like: Dam construction. The Amazon river dolphin, also known as the pink river dolphin or boto, lives only in freshwater. Its eye lacks a lens and has evolved a flat cornea. [9] River dolphins likely traveled from the Ganges River basin to the Indus via stream capture within the last five million years. Conservation efforts are underway to try to save these dolphins, but it is an uphill battle. Dolphins live in pods (groups) of up to a dozen individuals. The Trustees of The Natural History Museum, London, Keep up wot date with what Travis is working on by following him. It is not known the process of courtship and mating, and a calf is born 8 to 12 months after the intercourse more frequently between December and January and between March and May. Before they were drowned, the daughter was transformed into a dolphin and the general into a porpoise. In a 2005 survey in the same river stretch by the same investigating group a best estimate of 250 dolphins was recorded. The Ganges: India's sacred river | WWF The life span of the Ganges river dolphin is thought to be about 26 years. Extant river dolphins are placed in two superfamilies, Platanistoidea and Inioidea. India: National Ganga River Basin Authority, Ministry of Environment and Forests. [8], During the middle Miocene, the ancestor of Platanista entered the Indo-Gangetic Plain, then covered by inland seas, and remained there when sea levels dropped in the late Neogene and its environment converted to freshwater. The first breeding occurs between six and ten years of age and females give birth once every 2 or 3 years. (Platanista gangetica gangetica) Ganges river dolphins eat a large variety of small and medium sized fish and crustaceans19. Its close relative, Platanista minor (Indus river dolphin, bulhan, and Indus susu), is sometimes classified with P. gangetica as a subspecies and is found only in Pakistan. Only a few hundred were left by 1970. River dolphins swim by moving their tail fins and lower bodies up and down, propelling themselves through vertical movement, while their flippers are mainly used for steering. Create a list of articles to read later. [54], A baiji conservation dolphinarium was established at the Institute of Hydrobiology (IHB) in Wuhan in 1992. Watch on Abundance Surveys to estimate abundance or the number of the Ganges river dolphins have been conducted in many places in India, Nepal and the Sundarbans of Bangladesh. You will be able to access your list from any article in Discover. testing articles may only be saved for seven days. Males and females typically reach sexual maturity at approximately 10 years of age18. South Asian river dolphin - Wikipedia B. The primitive cetaceans, or archaeocetes, first took to the sea approximately 49 million years ago and became fully aquatic by 510 million years later. [24][25] Their clicks are about one octave below those of oceanic toothed whales of comparable size, meaning that they provide less information about the location of an object, but the dolphins' maxillary crests likely compensate by providing greater directional sensitivity. 'We found that there is no typical platanistoid inner ear shape,' explains Mariana. [44] The abundance of distinct fish species lures the Amazon River dolphin into the vrzea areas of high water occurrences during the seasonal flooding. [3], The current classification of river dolphins is as follows:[2][4][5], In 2012 the Society for Marine Mammalogy began considering the Bolivian (Inia geoffrensis boliviensis) and Amazonian (Inia geoffrensis geoffrensis) subspecies as full species Inia boliviensis and Inia geoffrensis, respectively; however, much of the scientific community, including the IUCN, continue to consider the Bolivian population to be a subspecies of Inia geoffrensis. 15-21). Mammals in the Seas: Small cetaceans, seals, sirenians and otters. Science, 166, 1408-1410. [39][40] One of these ecosystems is a floodplain, or a vrzea forest, and is home to a large number of fish species which are an essential resource for human consumption. Transboundary water governance and diplomacy, Gabura to Glasgow: Act on climate change and biodiversity loss, Social Cohesion and Wildlife Conservation in a Humanitarian Crisis Setting: A, Meghna Knowledge Forum (MKF) lays the foundation for a multi-stakeholder, Commission on Education and Communication (CEC), Commission on Environmental, Economic and Social Policy (CEESP), World Commission on Environmental Law (WCEL), World Commission on Protected Areas (WCPA). The Ganges River dolphin lives not only in the . Our editors will review what youve submitted and determine whether to revise the article. [3][20] In the 19th century, this species was reported to have occurred throughout the Indus River system, from the Indus River Delta north to Kalabagh just south of the Himalayas, including all the main tributaries.