The Ganges river dolphin (''Platanista gangetica'') is a species of
toothed whale
The toothed whales (also called odontocetes, systematic name Odontoceti) are a parvorder of cetaceans that includes dolphins, porpoises, and all other whales possessing teeth, such as the beaked whales and sperm whales. Seventy-three species of ...
classified in the family
Platanistidae. It lives in the
Ganges
The Ganges ( ) (in India: Ganga ( ); in Bangladesh: Padma ( )). "The Ganges Basin, known in India as the Ganga and in Bangladesh as the Padma, is an international river to which India, Bangladesh, Nepal and China are the riparian states." is ...
and related rivers of South Asia, namely in the countries of
India
India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
,
Nepal
Nepal (; ne, :ne:नेपाल, नेपाल ), formerly the Federal Democratic Republic of Nepal ( ne,
सङ्घीय लोकतान्त्रिक गणतन्त्र नेपाल ), is a landlocked country in S ...
, and
Bangladesh
Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mos ...
.
It is related to the much smaller
Indus river dolphin
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 ...
which lives in the
Indus River in
Pakistan
Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's fifth-most populous country, with a population of almost 243 million people, and has the world's second-lar ...
and the
Beas River
The Beas River (Sanskrit: ; Hyphasis in Ancient Greek) is a river in north India. The river rises in the Himalayas in central Himachal Pradesh, India, and flows for some to the Sutlej River in the Indian state of Punjab. Its total length is ...
of northwestern India.
It is also known by the name ''susu'' (popular name) or "Sisu" (Assamese language) and ''shushuk'' (
Bengali
Bengali or Bengalee, or Bengalese may refer to:
*something of, from, or related to Bengal, a large region in South Asia
* Bengalis, an ethnic and linguistic group of the region
* Bengali language, the language they speak
** Bengali alphabet, the w ...
).
[, page 451 etter Aand page 568 etter S] The Ganges river dolphin has been recognized by the government of India as its
National Aquatic Animal and is the official animal of the Indian city of
Guwahati
Guwahati (, ; formerly rendered Gauhati, ) is the biggest city of the Indian state of Assam and also the largest metropolis in northeastern India. Dispur, the capital of Assam, is in the circuit city region located within Guwahati and is the ...
. Its first occurrence, within the Hooghly River, was documented b
William Roxburgh
Taxonomy
The Ganges river dolphin split from the
Indus river dolphin
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 ...
during the
Pleistocene
The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...
, around 550,000 years ago.
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.
The earliest fossil identified as belonging to the species is only 12,000 years old.
Etymology
The species has multiple common names throughout its range. It is known as ''susu'' as a popular name; ''soons'', ''soans'', or ''soos'' in
Hindi
Hindi ( Devanāgarī: or , ), or more precisely Modern Standard Hindi (Devanagari: ), is an Indo-Aryan language spoken chiefly in the Hindi Belt region encompassing parts of northern, central, eastern, and western India. Hindi has been ...
; ''shushuk'' in
Bengali
Bengali or Bengalee, or Bengalese may refer to:
*something of, from, or related to Bengal, a large region in South Asia
* Bengalis, an ethnic and linguistic group of the region
* Bengali language, the language they speak
** Bengali alphabet, the w ...
; ''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
Sanskrit (; attributively , ; nominally , , ) is a classical language belonging to the Indo-Aryan branch of the Indo-European languages. It arose in South Asia after its predecessor languages had diffused there from the northwest in the late ...
name in
medieval
In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire ...
times was likely ''shishumar'', and during the
Mughal era
The Mughal Empire was an early-modern empire that controlled much of South Asia between the 16th and 19th centuries. Quote: "Although the first two Timurid emperors and many of their noblemen were recent migrants to the subcontinent, the d ...
, it was known as ''pani suar''.
Distribution
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.
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.
Description
The Ganges river dolphin has a rectangular, ridgelike dorsal fin and females tend to be larger than males.
Ganges river dolphins usually are tan, chocolate brown 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.
They have a large melon head used for
echolocation, because they cannot see well. Their eyes are usually small due to the cloudy water.
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.
Behavior
The Ganges river dolphins usually come in pairs or they're just single and are not known to do acrobatic maneuvers near boats or when they're distressed. Little is known about their behavior because they are usually shy around boats and are hard to observe. They are known to breach; however this is rare.
Vocalization
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.
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. Produced pulse trains are similar in wave form and frequency to the echolocation patterns of the
Amazon river dolphin
The Amazon river dolphin (''Inia geoffrensis''), also known as the boto, bufeo or pink river dolphin, is a species of toothed whale classified in the family Iniidae. Three subspecies are currently recognized: ''I. g. geoffrensis'' (Amazon river ...
. Both species regularly produce frequencies lower than 15 kHz and the maximum frequency is thought to fall between 15 and 60 kHz.
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. Given the dolphin's blindness, it produces an ultrasonic sound that is echoed off other fish and water species, allowing it to identify prey.
Reproduction
The dolphin does not have a specific mating season. When a calf is born, 8–12 months after conception, it will stay with its mother for one year.
Diet
Ganges river dolphins use echolocation to find food. They eat
crustaceans
Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean gro ...
such as
prawns and fish including
carp,
mahseer
Mahseer is the common name used for the genera '' Tor'', ''Neolissochilus'', '' Naziritor'' and ''Parator'' in the family Cyprinidae (carps). The name is, however, more often restricted to members of the genus ''Tor''.Sen TK, Jayaram KC, 1982. Th ...
, and even sharks such as the
Ganges shark
The Ganges shark (''Glyphis gangeticus'') is a critically endangered species of requiem shark found in the Ganges River (Padma River) and the Brahmaputra River of Bangladesh and India. It is often confused with the more common bull shark (''Car ...
(''Glyphis gangeticus''). They may also take birds and turtles.
Human interaction
![Ganga Kalighat 1875](https://upload.wikimedia.org/wikipedia/commons/0/08/Ganga_Kalighat_1875.jpg)
The Ganges River dolphin has been listed as endangered under the IUCN Red List since 1996. Human activity has played a large role in the reduction of both their native range and population size. The Ganges river dolphin and other freshwater dolphin species have faced declines in population from stressors such as noise pollution, ship traffic, and fishery bycatch. Anthropogenic activity like dam construction and hydroelectric power plants also contribute to their endangered status. They are also endangered due to pollution and overfishing for oil.
[ 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
An aphrodisiac is a substance that increases sexual desire, sexual attraction, sexual pleasure, or sexual behavior. Substances range from a variety of plants, spices, foods, and synthetic chemicals. Natural aphrodisiacs like cannabis or cocai ...
, and as bait for catfish
Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive ...
. Poisoning of the water supply from 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. An immediate danger for the species in National Chambal Sanctuary is the decrease in river depth and appearance of sand bars dividing the river course into smaller segments, as irrigation has lowered water levels throughout their range.
Mythology and folklore
The Ganges dolphin is associated with Ganga and is occasionally the depiction of her vahana
''Vahana'' ( sa, वाहन, or animal vehicle, literally "that which carries, that which pulls") denotes the being, typically an animal or mythical, a particular Hindu God is said to use as a vehicle. In this capacity, the vahana is often ...
, the makara
''Makara'' ( sa, मकर, translit=Makara) is a legendary sea-creature in Hindu mythology. In Hindu astrology, Makara is equivalent to the Zodiac sign Capricorn.
Makara appears as the vahana (vehicle) of the river goddess Ganga, Narmada, a ...
.
Conservation
A 2017 population assessment estimated that less than 3,500 individuals of ''Platanista gangetica'' exist throughout the species' range. The underlying surveys are temporally patchy and believed to contain uncertainty.
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
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 Sa ...
, the first such protected area.
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 Ramayan, highlighted the force by which the Ganges emerged from Lord Shivji's locks and along with this force came many species such as animals, fish, and the Shishumaar—the dolphin.
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 ax. On 7 January 2021, three people were arrested.
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.
Nonhuman personhood
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.
Project Dolphin
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.
References
External links
*
{{Symbols of India
River dolphins
Mammals of India
Mammals of Nepal
Mammals of Bangladesh
Mammals described in 1801
EDGE species
National symbols of India