Black softshell turtle

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Black softshell turtle
Bostami turtle 5.jpg
CITES Appendix I (CITES) [2]
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Testudines
Suborder: Cryptodira
Family: Trionychidae
Genus: Nilssonia
Species:
N. nigricans
Binomial name
Nilssonia nigricans
(Anderson, 1875) [1]
Synonyms [3] [4]
  • Trionyx nigricans
    Anderson, 1875
  • Amyda nigricans
    — Mertens, L. Müller & Rust, 1934
  • Aspideretes nigricans
    — Meylan, 1987
  • Trionix nigricans
    — Richard, 1999
  • Nilssonia nigricans
    — Praschag et al., 2007
The side profile of an adult Bostami turtle Bostami Turtle.jpg
The side profile of an adult Bostami turtle

The black softshell turtle or Bostami turtle (Nilssonia nigricans), previously placed in genus Aspideretes , is a species of freshwater turtle found in India (Assam and Tripura) and Bangladesh (Chittagong and Sylhet). It was long believed to consist of inbred individuals of the Indian softshell turtle (A. gangeticus or N. gangeticus) or the Indian peacock softshell turtle (A. hurum or N. hurum), but while it is a close relative of the latter, it is a distinct species. [5] In the 1800s it was believed these turtles were brought from Iran to Chittagong shrine pond by Hazrat Bayezid Bostami. His turtles he had brought to this pond were treated as sacred and respected by the public. [6] Previously declared extinct by the International Union for Conservation of Nature in 2002, these turtles were found still to exist in a temple's pond called the Hayagriva Madhava Temple located in Assam, and in Kalyan Sagar lake in Tripura Sundari Temple in Udaipur, Tripura, India. [7] Through conservation methods and protection of the species, some of these turtles can be found today throughout the wild, and scientists and environmental biologists are continuing to work hard to preserve this endangered species and their natural habitat. Their mitogenome represents relatedness to 19 other species of the Testudines. When looking at the phylogenetic tree, Nilssonia nigricans is a sister group to Nilssonia formosa . [8]

Contents

Habitat

Originally native to the lower Brahmaputra River, the only population ever reliably known consists of a number of the species in a man-made pond which is part of the Bayazid Bostami shrine at Chittagong, where they are dependent on humans for survival. To the locals and worshipers, the black softshell turtle is known as mazari ("Mazar inhabitant"); specimens from this shrine were used in the first scientific description. [5] [9]

In a 2014 survey by Poribesh Banchao Andolon, a Bangladeshi private organization it was found that the amount of oxygen dissolved in the pond water was 2.01 mg/L, whereas the favorable level is 5 mg/L. [10] In 2012, wildlife biologists of the Center for Advanced Research in Natural Resources and Management found a small population in the wild of Sylhet. [10] Two tiny wild populations were discovered in Assam, in Kaziranga and in the Jia Bhoroli River which is a northern tributary of the Brahmaputra. Also, another temple population of these turtles was identified in the Kasopukhuri pond on Nilachal Hill, next to the Kamakhya Temple at Guwahati in Assam. [11] Another temple population is found in the kalyan sagar lake of Tripureshwari temple, Udaipur, Tripura. These turtles are also found in the pond in Baneswar Shiva temple, a shiva temple in Baneswar in the Cooch Behar II CD block in the Cooch Behar Sadar subdivision of the Cooch Behar district in West Bengal, India.

Biology

Appearance

The black softshell turtle has an observably different appearance compared to that of a common turtle. This turtle, similar to all other softshell turtles, has a semi-flexible shell that is leathery, and does not obstruct movement as much as the average hardshell. The black softshell turtle also has a very distinct nose and face, with a tube like structure protruding from its nose resembling and functioning similar to a snorkel. The ligaments of this turtle are also much more distinct than those of the normal sea turtle or land tortoise, being that they have hand-like structures that are webbed, as opposed to other turtles like sea turtles who have a wider arm. [12] The softshell of the turtle does not protrude out from the body very far, and typically appears somewhat rigid with very little color and design. [7] The skin of the black softshell turtle is often black or dark brown, but can often appear with white to yellow spots that appear across the head and ligaments of the turtle. [13]

Size and weight

The average Bostami turtle adult size can range from widths of 15 inches to 31 inches, and corresponding lengths of 13 inches to 28 inches. The average area of the species can range from 195 inches squared on the low end and 868 inches squared on the larger end. However, the highest recorded size for these turtles is a length of 35 inches. [12] The weight for the average female is around 120 pounds, while the weight of the males has not yet been recorded. However, these males are visually larger indicating strong chances of a larger corresponding weight. [14]

Life span and mortality rate

The highest recorded age for the Bostami turtle has been determined by those living in the area directly, with claims that the oldest turtles present are approximately 150 years old. [15] However, this species has a high mortality rate at the beginning stages of life, with 94% of eggs without hatching capabilities. With an average clutch size of 20, this would allow for the survival of about one egg per two mating turtles. [14]

Diet

With the species existing in very limited areas with high human traffic, these turtles have become dependent upon visitors for feeding. Visitors tend to feed a mixture of grains, fruits, and various meat products. [15] These interactions with direct feeding have created a dependence for these turtles on the people, since this species no longer has a need for hunting. This had made it hard to determine the natural diet of the species. However, with the ability to consume the foods provided by the people, their diet is commonly compared to that of other species within the same genus. These organisms are on the omnivore scale of the food consumption, consisting of plants and small animals like fish and worms. [12]

Reproduction

Visitors feeding the turtles in the pond. Feeding the turtles 01.jpg
Visitors feeding the turtles in the pond.

Nilssonia nigricans are oviparous organisms, in which they reproduce by laying their young as eggs to be hatched. [16] Softshell turtles are known to mature slowly with the males prepared to breed in their fourth year. The female population could take up to seven to nine years to mature. [17] A group of eggs is known as a clutch and a female black soft shelled turtle can lay anywhere between 10 and 38 eggs in her clutch. The baby turtles will grow in their eggs for 92–108 days before hatching. [12] Recently the hatching rate for this specific species has been decreasing due to these species being endangered.

Behavior

Hibernation

Hibernation takes place during the late autumn season until the spring for softshell turtles. They bury themselves at the bottom of a river/lake in the mud. Food is not as essential as oxygen during this period. Oxygen is needed at a reduced rate than normal and the turtles practice a technique called “pharyngeal breathing”. [17] This means that they pump water in and out of their throat (pharynx) that contain microvillus projections of small blood vessels. This structure provides them with greater surface area to absorb more oxygen. [18]

Near-extinction in the wilderness

The Bayazid Bostami shrine with its pond Baizid Bostami's Mazar 002.JPG
The Bayazid Bostami shrine with its pond

In 2002, the International Union for Conservation of Nature classified the species as Extinct in the Wild. In 2004, 408 turtles were found in the pond of the Bayazid Bostami shrine. According to the shrine committee staff, 90 more turtles were hatched in the pond in 2007, 74 in 2008, 96 in 2009, 28 in 2010, 45 in 2012 and 40 in 2014. [10]

In 2017, a singular wild turtle was found in the wetlands of Old Akuk Village in Wokha District, Nagaland. DNA from the specimen sent to Bangladesh was tested and ultimately confirmed that it was a member of the black softshell species. [19]

This extinction has been caused by human intervention, specifically the migration of people into the habitat and the contamination of water and land following this movement. [20] The land of Bangladesh that N. nigricans have been able to occupy currently had been tested for conditions of survival and mating. The survival rate of juvenile N. nigricans is relatively low due to a low mortality of egg hatching and juvenile survival following hatching. [21]

Human captivity of black softshell turtles for religious contexts seems to both benefit and harm turtle populations. Shrines keep these turtles in areas protected from outside predators, but these ponds are not suitable for sustained repopulation efforts. In Hinduism, the black softshell turtle represents an incarnation of the deity Kurma. Worshipers come and feed the turtles in the ponds human foods such as biscuits. Such dietary items are harmful to the turtles, often leading to malnourishment. [22]

A Bostami turtle being fed by human visitors. Feeding the turtles 03.jpg
A Bostami turtle being fed by human visitors.

Human intervention has also caused a push towards extinction with intentional methods of poisoning. In 2006 there was a mass poisoning of the turtles within the Bostami Shrine pond by poachers in the area. This event occurred within the research period, as the turtles were under heavy observations and were protected from this event, while this not being the first time this method had been used. In this case many of the fish utilized by the N. nigricans for food had been poisoned, making nutrition unsustainable for the turtles. This same poisoning also changed the oxygen levels in the water, making it unsustainable for the turtles. A waiting period had passed to ensure oxygen levels were rich in the water, indicating a sustainable environment, in turn allowing the release of the species. [21]

Conservation efforts

Since 2013, TSA India has worked diligently to improve conditions at selected temple ponds in Assam where these turtles were discovered. Many of the ponds were eutrophic and overcrowded and often, turtles were fed human food as religious offerings. The turtles showed signs of poor nutrition and a lack of suitable nesting space resulted in eggs being deposited in areas where there was little chance of hatching. The goal of the project is to eventually rear and release juveniles from these captive colonies to supplement depleted wild populations. As part of that initiative, the TSA India team camped at the Nagshankar temple in April to observe nesting in the 40-45 adult females at that location. At that time, the team transferred ten nests to a hatchery and protected four nests onsite.

With TSA's efforts 44 turtles have hatched so far. The team is currently expanding a headstarting facility at Nagshankar temple to accommodate the turtle's hatchlings of 2016. Neonates and juveniles cannot be released back into the temple pond due to predation by larger turtles and exotic fish. For this reason, the team acquired an earthen pond in the nearest village to provide space for the fast-growing juveniles, improving survival prospects for this extremely rare softshell.

In 2018, Das et al. had collected population sizes of N. nigricans from 2006 to 2012. The population size had shown a gradual increase over time, indicating that the calculated area per turtle had decreased in accordance. He indicated that without an increase in habitat size, the carrying capacity of the species will be reached quicker. This can decrease the overall growth of the species and not allow it to grow past the current conservation status. [21]

In 2011, Dr. Jayaditya from the Help Earth NGO found a grouping of black softshell turtles in a temple pond in Hajo, Assam. He revitalized contributions aimed towards saving and replenishing the species once again. He and his team embanked the sides of the temple pond and made adjustments to simulate a natural river system and create an ecosystem more conducive to the turtle's natural habitat. Thereafter, they observed a positive egg ratio produced around the temple premises. The State Zoo of Assam is playing an important role in this conservation project, serving as the location where baby turtles are reared for six months. When deemed fit and healthy, and capable of surviving, the young turtles are released into the wild. As of 2016, the State Zoo of Assam has released 300 turtles. Now 16 temples in Assam are helping in this important project. Similar conservation efforts have been undertaken in Tripura in Tripura sundari temple, matabari, udaipur, tripura, to protect the indigenous populations of Bostami turtles.

Related Research Articles

<span class="mw-page-title-main">Trionychidae</span> Family of turtles

The Trionychidae are a taxonomic family of a number of turtle genera, commonly known as softshell turtles. The family was erected by Leopold Fitzinger in 1826. Softshells include some of the world's largest freshwater turtles, though many can adapt to living in highly brackish areas. Members of this family occur in Africa, Asia, and North America, with extinct species known from Australia. Most species have traditionally been included in the genus Trionyx, but the vast majority have since been moved to other genera. Among these are the North American Apalone softshells that were placed in Trionyx until 1987.

<span class="mw-page-title-main">Indian flapshell turtle</span> Species of freshwater turtle predominant in South Asia

The Indian flapshell turtle is a freshwater species of turtle found in South Asia. The "flap-shelled" name stems from the presence of femoral flaps located on the plastron. These flaps of skin cover the limbs when they retract into the shell. It is unclear what protection the flaps offer against predators. Indian flapshell turtles are widespread and common in the South Asian provinces. It is morphologically an evolutionary link between the softshell and hardshell aquatic turtles. Exploitation for profit and habitat change are threats to their survival.

<span class="mw-page-title-main">Asian giant softshell turtle</span> Species of freshwater turtle

The Asian giant softshell turtle, also known commonly as Cantor's giant softshell turtle and the frog-faced softshell turtle, is a species of freshwater turtle in the family Trionychidae. The species is native to Southeast Asia. The species is critically endangered and in the 20th century has disappeared from much of its former range.

<span class="mw-page-title-main">Leith's softshell turtle</span> Species of reptile

Leith's softshell turtle is a species of turtle in the family Trionychidae. The species is found in peninsular Indian rivers including the Thungabhadra, Ghataprabha, Bhavani, Godavari, Kaveri and Moyar Rivers. The type locality is Pune in India.

<span class="mw-page-title-main">Indian peacock softshell turtle</span> Species of freshwater turtle

Indian peacock softshell turtle is a species of turtle found in South Asia and is listed on the IUCN Red List as a vulnerable species.

<span class="mw-page-title-main">Indian softshell turtle</span> Species of freshwater turtle

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.

<span class="mw-page-title-main">Northern river terrapin</span> Species of turtle

The northern river terrapin is a species of riverine turtle native to Southeast Asia. It has been classified as Critically Endangered on the IUCN Red List and considered extinct in much of its former range; as of 2018, the population in the wild was estimated at 100 mature individuals.

<span class="mw-page-title-main">Assam roofed turtle</span> Species of turtle

The Assam roofed turtle or Sylhet roofed turtle is a turtle species of the family Geoemydidae found in the Brahmaputra-Meghna drainage in India (Assam) and parts of eastern Bangladesh. It was formerly placed in the genus Batagur and the defunct genus Kachuga.

<span class="mw-page-title-main">Spiny softshell turtle</span> Species of turtle

The spiny softshell turtle is a species of softshell turtle, one of the largest freshwater turtle species in North America. Both the common name, spiny softshell, and the specific name, spinifera (spine-bearing), refer to the spiny, cone-like projections on the leading edge of the carapace, which are not scutes (scales).

<span class="mw-page-title-main">Tripura Sundari Temple</span> Hindu temple in Tripura, India

Tripura Sundari Temple is a Hindu temple of the Goddess Tripura Sundari, better known locally as Devi Tripureshwari. The temple is situated in the ancient city of Udaipur, about 55 km from Agartala, Tripura and can be reached by train and road from Agartala. It is believed to be one of the holiest Hindu shrines in this part of the country and witnesses the highest number of visitors for a temple in North-East India, after Kamakhya Temple in Assam. The state of Tripura is named after this temple. Popularly known as Matabari, the shrine is set upon a small hillock that resembles the hump of a tortoise (Kurma). This shape called Kurmapṛṣṭhākṛti is considered the holiest possible site for a Shakti temple, hence also bestowing the name of Kurma Pīṭha. The Goddess is served by traditional Brahmin priests.

<span class="mw-page-title-main">Yangtze giant softshell turtle</span> Critically endangered species of turtle

The Yangtze giant softshell turtle, also known commonly as the Red River giant softshell turtle, the Shanghai softshell turtle, the speckled softshell turtle, and Swinhoe's softshell turtle, is an extremely rare species of turtle in the family Trionychidae. It may be the largest living freshwater turtle in the world. The species is native to eastern and southern China and northern Vietnam. With a known population of only two or three individuals, and with the last known females dying out, this species is considered functionally extinct.

<span class="mw-page-title-main">Asiatic softshell turtle</span> Species of turtle

The Asiatic softshell turtle or black-rayed softshell turtle is a species of softshell turtle in the Trionychidae family. Despite its name, it is not the only softshell turtle in Asia.

<span class="mw-page-title-main">Burmese peacock softshell</span> Species of turtle

The Burmese peacock softshell turtle is a species of softshell turtle in the Trionychidae family. It is one of five species in the genus Nilssonia.

<i>Nilssonia</i> (turtle) Genus of turtles

Nilssonia is a genus of softshell turtles from rivers, streams, ponds, and lakes in South Asia and Burma. In many treatments, it is monotypic, with the single species Burmese peacock softshell. However, the supposed other genus of peacock softshells, Aspideretes, is more closely related to N. formosa than had been believed. They differ only in the neural plates between the first pleural scale pair of the bony carapace, which are fused into one in N. formosa and unfused in the others.

A. nigricans may refer to:

<span class="mw-page-title-main">Shrine of Bayazid Bostami</span>

The Shrine of Bayazid Bostami is a shrine in Chattogram, Bangladesh. Bayazid Bostami was a famous Persian Sufi born in Bostam, Iran. Its shrine area as a complex consists of a tomb surrounded by a brick structure along with an old mosque and a large pond. There is no significant historical evidence about Bostami's visit and tomb in this area. The whole complex is located on a hillock of Nasirabad, considered to be a holy place and attracts a large number of visitors and pilgrims daily.

The Burmese narrow-headed softshell turtle, also known commonly as the Myanmar narrow-headed softshell turtle and Van Dijk's chitra, is a species of turtle in the family Trionychidae. The species is endemic to Southeast Asia.

<span class="mw-page-title-main">Southeast Asian softshell turtle</span> Species of softshell turtle

The Southeast Asian softshell turtle is a species of softshell turtle in the family Trionychidae.

References

  1. 1 2 Praschag, P.; Ahmed, M.F.; Singh, S. (2021). "Nilssonia nigricans". IUCN Red List of Threatened Species . 2021: e.T2173A2778172. doi: 10.2305/IUCN.UK.2021-1.RLTS.T2173A2778172.en . Retrieved 19 November 2021.
  2. ↑ "Appendices | CITES". cites.org. Retrieved 2022-01-14.
  3. ↑ Fritz Uwe; Peter Havaš (2007). "Checklist of Chelonians of the World" (PDF). Vertebrate Zoology. 57 (2): 311. doi: 10.3897/vz.57.e30895 . ISSN   1864-5755. S2CID   87809001.
  4. ↑ "Nilssonia nigricans". The Reptile Database. www.reptile-database.org.
  5. 1 2 Praschag et al. (2007)
  6. ↑ "'Bostami turtle' found in wild". The Daily Star. 13 July 2020.
  7. 1 2 Weston, Phoebe (11 June 2019). "Indian temple helps nurture 'extinct' turtle back to life". Independent.
  8. ↑ Kundu, Shantanu; Kumar, Vikas; Tyagi, Kaomud; Chakraborty, Rajasree; Singha, Devkant; Rahaman, Iftikar; Pakrashi, Avas; Chandra, Kailash (2018-11-26). "Complete mitochondrial genome of Black Soft-shell Turtle (Nilssonia nigricans) and comparative analysis with other Trionychidae". Scientific Reports. 8 (1): 17378. Bibcode:2018NatSR...817378K. doi:10.1038/s41598-018-35822-5. ISSN   2045-2322. PMC   6255766 . PMID   30478342.
  9. ↑ Anderson (1875), Praschag et al. (2007)
  10. 1 2 3 Uddin, Minhaj (17 March 2015). "Rare Bostami Turtles of Ctg city in peril". The Daily Star . Retrieved 2015-08-17.
  11. ↑ Asmat (2002), Praschag & Gemel (2002), Praschag et al. (2007)
  12. 1 2 3 4 Brock (2020). "Black Softshell Turtle (Bostami Turtle)". All Turtles.
  13. ↑ Glenn, C (2006). "Black Softshell Turtle". Earth's Endangered Creatures.
  14. 1 2 "Bostami Turtle - Banglapedia". en.banglapedia.org. Retrieved 2020-04-17.
  15. 1 2 Abu Saeed, M (2009). "Bostami Turtle (Aspideretes nigricans) No Longer Endemic Only to Bangladesh". Tiger Paper. 36: 29–32.
  16. ↑ "Species | The Reptile Database". reptile-database.reptarium.cz. Retrieved 2020-04-17.
  17. 1 2 "How Do Softshell Turtles Survive?". animals.mom.me. Retrieved 2020-04-17.
  18. ↑ "Pharyngeal Breathing in Softshell Turtles | Center for Environmental Communication | Loyola University New Orleans". www.loyno.edu. Retrieved 2020-04-17.
  19. ↑ Longchar, Imiti. "Turtle species thought extinct in the wild discovered in Nagaland". Morung Express. Retrieved 2017-03-24.
  20. ↑ "IUCN Red List of Threatened Species: Black Softshell Turtle". IUCN Red List of Threatened Species. 2002-01-01. Retrieved 2020-04-17.
  21. 1 2 3 Das, Subhasish Das (June 2018). "Conservation Status of Black Soft Shell Turtle (Nilssonia nigricans) in Bangladesh". ResearchGate. 6: 12–16.
  22. ↑ "Who's Protecting Who? The rediscovery of the Black Softshell turtle in the wild". Lost & Found - Positive Conservation Storytelling. 2019-09-14. Retrieved 2022-04-27.

Bibliography

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