Ganges river dolphin Early | |
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Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Artiodactyla |
Infraorder: | Cetacea |
Family: | Platanistidae |
Genus: | Platanista |
Species: | P. gangetica |
Binomial name | |
Platanista gangetica (Lebeck, 1801) | |
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Ranges of the Indus river dolphin and Ganges river dolphin | |
Synonyms | |
Platanista gangetica gangetica |
The Ganges river dolphin (Platanista gangetica) is a species of freshwater dolphin classified in the family Platanistidae. It lives in the Ganges and related rivers of South Asia, namely in the countries of India, Nepal, and Bangladesh. [3] It is related to the much smaller Indus river dolphin which lives in the Indus River in Pakistan and the Beas River of northwestern India. [4]
It is also known by the name susu (popular name) also hihu or huhu (Assamese : শিশু, শুশুক) in Assam and shushuk (Bengali : শুশুক) in West Bengal and Bangladesh. [5] The Ganges river dolphin has been recognized by the Government of India as its National Aquatic Animal [6] and is the official animal of the Indian city of Guwahati. [7] Its first occurrence, within the Hooghly River, was documented by William Roxburgh. [8]
The Ganges river dolphin has a rectangular, ridgelike dorsal fin and females tend to be larger than males. [9] Ganges river dolphins usually are tan, chocolate brown, dark grey or light blue. They have an elongated, slender snout with sharp and very pointed teeth, similar to most river dolphins. The river dolphin has a rounded belly which, combined with their rectangular dorsal fin, makes them look particularly stocky in build compared to other dolphins. Their flippers and tail flukes are large and broad. [10] They have a large melon head used for echolocation, because they cannot see well. Their eyes are usually small due to the cloudy water. [9] Ganges river dolphins are usually 2.2–2.6 meters long (7–8 ft). The oldest recorded animal was a 28-year-old male, 199 cm in length, although they are estimated to live up to 30 years old. [10] [11]
The Ganges river dolphin split from the Indus river dolphin during the Pleistocene, around 550,000 years ago. [1] The earliest fossil identified as belonging to the species is only 12,000 years old. [12]
The Ganges river dolphin was formally classified as Delphinus gangeticus two separate times in 1801, by Heinrich Julius Lebeck [13] and William Roxburgh. They both likely used the type specimen, caught near Calcutta in late 1797 and sent to the Hunterian Museum in London. It may have been destroyed during World War II, but castings were previously made of the rostrum and parts of the lower jaw, which survive at the Natural History Museum. [14] Whether Lebeck or Roxburgh should be given credit has been debated over the centuries, but research by Kinze (2000) found that Lebeck's description was published on the 24 August while Roxburgh's was likely published no earlier than September, thus giving Lebeck the priority. [14] [15] Elisha Gray coined the species name Platanista gangetica in 1835. [14]
This species and the Indus river dolphin, were initially classified as a single species, Platanista gangetica, but in the 1970s both were split into distinct species. However, in the 1990s, both species were again grouped as a single species. However, more recent studies of genes, divergence time, and skull structure support both being distinct species. [16] [14]
The species has multiple common names throughout its range. It is known as susu as a popular name, soons, soans, or soos in Hindi, shushuk in Bengali, hiho or hihu in Assamese, bhagirath (as a reference to the character of the same name from Hindu mythology), and shus or suongsu in Nepali. Its Sanskrit name in medieval times was likely shishumar, and during the Mughal era, it was known as pani suar. [14]
It lives along the Ganges-Brahmaputra-Meghna and Karnaphuli-Sangu river systems of Bangladesh and India, and the Sapta Koshi and Karnali Rivers in Nepal. [17] [18] The Ganges river dolphin favours deep pools, eddy countercurrents located downstream of the convergence of rivers and of sharp meanders, and upstream and downstream of midchannel islands. [18] [19]
The Ganges river dolphins usually swim alone or in pairs, they are known to breach rarely and are shy around boats and therefore difficult to observe. [9]
This species shows object-avoidance behavior in both the consistently heavily murky waters of its habitat and in clear water in captivity, suggesting it is capable of using echolocation effectively to navigate and forage for prey. [20] Information is limited on how extensively vocalization is used between individuals. It is capable of performing whistles, but rarely does so, suggesting that the whistle is a spontaneous sound and not a form of communication. The Ganges river dolphin most typically makes echolocation sounds such as clicks, bursts, and twitters. [21] Produced pulse trains are similar in wave form and frequency to the echolocation patterns of the Amazon river dolphin. Both species regularly produce frequencies lower than 15 kHz and the maximum frequency is thought to fall between 15 and 60 kHz. [20]
Echolocation is also used for population counts by using acoustic surveying. This method is still being developed and is not heavily used due to cost and technical skill requirement. [22] Given the dolphin's blindness, it produces an ultrasonic sound that is echoed off other fish and water species, allowing it to identify prey. [23]
The Ganges river dolphin does not have a specific mating season. When a calf is born, 8–12 months after conception, it stays with its mother for one year. [24]
The Ganges river dolphin finds food through echolocation and feeds on crustaceans such as prawns and fish including carp, mahseer, and even sharks such as the Ganges shark (Glyphis gangeticus). It also takes birds and turtles. [24]
The Ganges river dolphin has been listed as an Endangered species on the IUCN Red List since 1996. It is threatened by habitat fragmentation due to reduced dry-season river flows, entanglement in fishing gear and by-catch mortality, targeted hunting, pollution of rivers in proximity to urban areas and intensive agricultural landscapes; it is disturbed by inland navigation and potentially threatened by seismic surveys, oil well blowouts, and the effects of climate change on hydrological dynamics. [2] Human activity has played a large role in the reduction of its native range and population size due to stressors such as noise pollution, ship traffic and fishery bycatch, construction of dams and hydroelectric power plants. [25] It is also endangered due to pollution and overfishing for oil. [3] [2] Entanglement in fishing nets as bycatch can cause significant damage to local populations, and individuals are taken each year by hunters; their oil and meat are used as a liniment, as an aphrodisiac, and as bait for catfish. Poisoning of the water supply by industrial and agricultural chemicals may also have been a contributing factor towards population decline, as these chemicals are biomagnified in the bodies of the dolphins. [26] An immediate danger in National Chambal Sanctuary is the decrease in river depth and appearance of sand bars dividing the river course into smaller segments. [27]
In 2017, it was estimated that the global Gangetic river dolphin population comprised less than 3,500 individuals. The underlying surveys are temporally patchy and believed to contain uncertainty.[ citation needed ]
The Ministry of Environment and Forest declared the Gangetic dolphin the national aquatic animal of India. A stretch of the Ganges River between Sultanganj and Kahlgaon in Bihar has been declared a dolphin sanctuary and named Vikramshila Gangetic Dolphin Sanctuary, the first such protected area.[ citation needed ]
The Uttar Pradesh government in India is propagating ancient Hindu texts in hopes of raising the community support to save the dolphins from disappearing. One of the lines being versed from Valimiki's Ramayana, highlighted the force by which the Ganges emerged from Shiva's locks and along with this force came many species such as animals, fish, and the Shishumaar—the dolphin. [28]
On 31 December 2020, a dead adult dolphin was found at the Sharda canal in the Pratapgarh district in India. A video circulated on social media showing a dozen men beating the dolphin with sticks and an axe. On 7 January 2021, three people were arrested. [29] Similarly, there is another news story in which a few fishermen caught one Gangetic dolphin and feasted upon it, leading to their arrest by Kaushambhi police in Uttar Pradesh. [30]
The species is protected from international trade by its listing in Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora. This makes commercial international trade prohibited. [2]
Bangladesh has established six sanctuaries in the Sundarbans. [31]
On 20 May 2013, India's Ministry of Environment and Forests declared dolphins 'nonhuman persons' and as such has forbidden their captivity for entertainment purposes; keeping dolphins in captivity must satisfy certain legal prerequisites. [32]
On the occasion of the 74th Independence Day, 15 August 2020, the Indian Ministry of Environment, Forest and Climate Change announced 'Project Dolphin' to boost conservation of both river and oceanic dolphins. [33]
The Ganges dolphin is associated with Ganga and is occasionally the depiction of her vahana, the makara. [34]
River dolphins are a polyphyletic group of fully aquatic mammals that reside exclusively in freshwater or brackish water. They are an informal grouping of dolphins, which itself is a paraphyletic group within the infraorder Cetacea. Extant river dolphins are placed in two superfamilies, Platanistoidea and Inioidea. They comprise the families Platanistidae, the recently extinct Lipotidae, Iniidae and Pontoporiidae. There are five extant species of river dolphins. River dolphins, alongside other cetaceans, belong to the clade Artiodactyla, with even-toed ungulates, and their closest living relatives the hippopotamuses, from which they diverged about 40 million years ago. Specific types of dolphins can be pink.
South Asian river dolphins are toothed whales in the genus Platanista, which inhabit the waterways of the Indian subcontinent. They were historically considered to be one species with the Ganges river dolphin and the Indus river dolphin being subspecies. Genetic and morphological evidence led to their being described as separate species in 2021. The Ganges and Indus river dolphins are estimated to have diverged 550,000 years ago. They are the only living members of the family Platanistidae and the superfamily Platanistoidea. Fossils of ancient relatives date to the late Oligocene.
The Indo-Pacific humpback dolphin is a species of humpback dolphin inhabiting coastal waters of the eastern Indian and western Pacific Oceans. This species is often referred to as the Chinese white dolphin in mainland China, Macau, Hong Kong, Singapore and Taiwan as a common name. Some biologists regard the Indo-Pacific dolphin as a subspecies of the Indian Ocean humpback dolphin which ranges from East Africa to India. However, DNA testing studies have shown that the two are distinct species. A new species, the Australian humpback dolphin, was split off from S. chinensis and recognized as a distinct species in 2014. Nevertheless, there are still several unresolved issues in differentiation of the Indian Ocean-type and Indo-Pacific-type humpback dolphins.
The Irrawaddy dolphin 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. It closely resembles the Australian snubfin dolphin, which was not described as a separate species until 2005. It has a slate blue to a slate gray color. Although found in much of the riverine and marine zones of South and Southeast Asia, the only concentrated lagoon populations are found in Chilika Lake in Odisha, India and Songkhla Lake in southern Thailand.
The Ganges shark is a critically endangered species of requiem shark found in the Ganges River and the Brahmaputra River of India and Bangladesh. It is often confused with the more common bull shark, which also inhabits the Ganges River and is sometimes incorrectly referred to as the Ganges shark. The genus is currently considered to contain three recent species; genetic evidence has shown that both the Borneo river shark and Irrawaddy river shark should be regarded as synonyms of the Ganges shark, expanding the range of the species to Pakistan, Myanmar, Borneo, and Java. While the other members of the genus Glyphis occur in coastal marine waters as well as rivers, the Ganges shark is found only in fresh water, making it the world's only exclusively freshwater shark. The species remains poorly known and very rare.
The gharial, also known as gavial or fish-eating crocodile, is a crocodilian in the family Gavialidae and among the longest of all living crocodilians. Mature females are 2.6 to 4.5 m long, and males 3 to 6 m. Adult males have a distinct boss at the end of the snout, which resembles an earthenware pot known as a ghara, hence the name "gharial". The gharial is well adapted to catching fish because of its long, narrow snout and 110 sharp, interlocking teeth.
The Ghaghara River, also known as the Karnali River in Nepal, Mapcha Tsangpo in Tibet, and the lower Ghaghara in Awadh is known as the Sarayu River, is a perennial trans-boundary river that originates in the northern slopes of the Himalayas in the Tibetan Plateau, cuts through the Himalayas in Nepal and joins the Sharda River at Brahmaghat in India. Together they form the Ghaghara River, a major left-bank tributary of the Ganges. With a length of 507 km (315 mi), it is the longest river in Nepal. The total length of the Ghaghara up to its confluence with the Ganges at Revelganj in Bihar is 1,080 km (670 mi). It is the largest tributary of the Ganges by volume and the second largest by length after Yamuna.
The Chambal River is a tributary of the Yamuna River in Central and Northern India, and thus forms part of the drainage system of the Ganges. The river flows north-northeast through Madhya Pradesh, running for a time through Rajasthan, then forming the boundary between Rajasthan and Madhya Pradesh before turning southeast to join the Yamuna in Uttar Pradesh state.
The Indian softshell turtle, or Ganges softshell turtle is a species of softshell turtle found in South Asia in rivers such as the Ganges, Indus and Mahanadi. This vulnerable turtle reaches a carapace length of up to 94 cm (37 in). It feeds mostly on fish, amphibians, carrion and other animal matter, but also takes aquatic plants. This turtle is listed in part II of Schedule I of the Wild Life (Protection) Act, 1972 and possession of this species is an offence.
The Upper Gangetic Plains moist deciduous forests is a tropical and subtropical moist broadleaf forests ecoregion of northern India.
Hastinapur Wildlife Sanctuary is a protected area in the Gangetic plains of Uttar Pradesh, India. It was established in 1986 and covers 2,073 km2 (800 sq mi) across Meerut, Muzzafarnagar, Ghaziabad, Bijnor, Meerut and Amroha districts. This area has not enjoyed protection needed to check poaching and various other threats to wildlife due to lack of proper notification.
Harike Wetland also known as "Hari-ke-Pattan", with the Harike Lake in the deeper part of it, is the largest wetland in northern India in the border of Tarn Taran Sahib district and Ferozepur district of the Punjab state in India.
Vikramshila Gangetic Dolphin Sanctuary is located in Bhagalpur District of Bihar, India. The sanctuary is a 60 kilometers stretch of the Ganges River from Sultanganj to Kahalgaon in Bhagalpur district. notified as Vikramshila Gangetic Dolphin Sanctuary in 1991, it is the protected area for the endangered Gangetic dolphins in Asia. Once found in abundance, only a few hundred remain, of which half are found here.
The Indus river dolphin is a species of freshwater dolphin in the family Platanistidae. It is endemic to the Indus River basin in Pakistan and Beas River in northwestern India. This dolphin was the first discovered side-swimming cetacean. It is patchily distributed in five small, sub-populations that are separated by irrigation barrages.
Squalodontidae or the shark-toothed dolphins is an extinct family of large toothed whales who had long narrow jaws. Squalodontids are known from all continents except Antarctica, from the Oligocene to the Neogene, but they had a maximal diversity and global distribution during the Late Oligocene and Early to Middle Miocene.
Ravindra Kumar Sinha is a Padma Shri awarded Indian biologist and environmentalist. He served as Vice-Chancellor of Shri Mata Vaishno Devi University from 2019-2023 and also served in Nalanda Open University. Previously he was the Head of the Department of Zoology at Patna University, and is a pioneer researcher and wildlife conservationist, famous for his efforts for the conservation of Gangetic Dolphins, he is popularly known as the "Dolphin Man of India".
The Beas Conservation Reserve covers an 185 km stretch of the river Beas. The area of the Reserve lies primarily in north-west Punjab. It was declared a conservation reserve by the government of Punjab, India in 2017. The Beas flows down meandering from the Himalayan foothills to Harike Headworks, where it spreads into multiple channels. The braided channels form islands and sand bars creating a complex environment that supports rich biodiversity. In September 2019, the reserve was declared a Ramsar site under the aegis of the 1971 Ramsar Convention on Wetlands of International Importance.
Heinrich Julius Lebeck was a Ceylon-born Dutch naturalist and specimen collector. He was educated in southern India, at a school run by Christoph Samuel John and later became a student of Carl Peter Thunberg. He described the Gangetic dolphin and the plant genus Lebeckia and the fish Ichthyscopus lebeck were named after him.
Pebanista is an extinct genus of platanistid "river dolphin" that lived during the Early to Middle Miocene in Peru. As a member of the Platanistidae, Pebanista is most closely related to the extant Ganges and Indus river dolphins (Platanista) of South Asia and shares no close relation to the modern Amazon river dolphin that inhabits the same region today. Like its close relatives, Pebanista possesses enlarged crests that would have covered the melon in life, possibly helping to focus their biosonar while hunting in murky waters. Pebanista further stands out as being the largest "river dolphin" yet discovered, reaching lengths between 2.8–3.47 m at minimum, much larger than the biggest recorded freshwater cetaceans of today. Given its relatively robust if elongated snout, it is thought that Pebanista was an active predator, profiting from the rich prey selection available to it in the enormous Pebas wetlands that covered South America during the early parts of the Miocene. Only a single species of Pebanista is known so far: P. yacuruna.