Aldabrachelys gigantea hololissa

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Seychelles giant tortoise
Aldabrachelys hololissa.jpg
A living specimen
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Testudines
Suborder: Cryptodira
Superfamily: Testudinoidea
Family: Testudinidae
Genus: Aldabrachelys
Species:
Subspecies:
A. g. hololissa
Trinomial name
Aldabrachelys gigantea hololissa
(GÜNTHER, 1877)
Synonyms [1]
  • Aldabrachelys gigantea hololissaGÜNTHER, 1877
  • Testudo hololissaGÜNTHER, 1875: 296 ( nomen nudum )
  • Testudo elephantinaDUMÉRIL & BIBRON, 1835: 221 ( ex errore ) — GÜNTHER 1877: 21
  • Testudo hololissaGÜNTHER, 1877: 39 ( part. )
  • Testudo giganteaSCHWEIGGER, 1812 ( ex errore ) ROTHSCHILD 1897: 407
  • Testudo daudiniiDUMÉRIL & BIBRON, 1835 ( ex errore ) ROTHSCHILD 1915: 433
  • Dipsochelys elephantinaDUMÉRIL & BIBRON, 1835 — BOUR 1994: 85
  • Dipsochelys hololissaLÜCKER, 2000
  • Geochelone hololissaFRITZ & HAVAS, 2006
  • Dipsochelys hololissaBONIN, ( et al ) 2006
  • Dipsochelys dussumieri hololissaTTWG, 2010
  • Aldabrachelys gigantea hololissaTTWG, 2012

The Seychelles giant tortoise (Aldabrachelys gigantea hololissa), also known as the Seychelles domed giant tortoise, is a tortoise subspecies in the genus Aldabrachelys .

Contents

It inhabited the large central granitic Seychelles islands, but was hunted in vast numbers by European sailors. By around 1840 it was presumed to be extinct, along with the Arnold's giant tortoise, a subspecies which shared the same islands.

It was recently[ when? ] rediscovered. Currently,[ when? ] a little over a hundred individuals exist. Many had been reestablished in the wild on forested islands such as Silhouette, but were evicted in 2011 by the Seychelles Islands Development Company. [2]

Description

Living adult specimens Dipsochelys hololissa.jpg
Living adult specimens

The three Aldabra-Seychelles giant tortoise subspecies can be distinguished based on carapace shape, however, many captive animals may have distorted carapaces and so may be difficult to identify.

The Seychelles giant tortoise (A. g. hololissa) is broad, flattened on the back and with raised scutes; it is usually a brownish-grey color. In comparison, the true Aldabra giant tortoise (A. g. gigantea) is a roundly-domed, black-colored subspecies. [3]

Life history

Giant tortoises are among the longest-lived animals on the planet. Some individual Aldabra giant tortoises are thought to be over 200 years of age, but this is difficult to verify because they tend to outlive their human observers. Adwaita was reputedly one of four brought by British seamen from the Seychelles Islands as gifts to Robert Clive of the British East India Company in the 18th century, and came to Calcutta Zoo in 1875. At his death in March 2006 at the Kolkata (formerly Calcutta) Zoo in India, Adwaita is reputed to have reached the longest ever measured life span of 255 years (birth year 1750). [4] Today, Jonathan, a 188-year-old, Saint Helena-dwelling Seychelles giant tortoise, is thought to be the oldest living terrestrial animal on Earth since the 2006 death of Harriet; a 176 year old Galapagos giant tortoise who lived at Australia Zoo. Coming in second to Jonathan is Esmeralda, at 176 years old. Esmeralda is an Aldabra giant tortoise living in the Galapagos Islands. [5] There's a report that a tortoise was kept in the garrison by French explorer Chevalier Marc-Joseph Marion du Fresne. The creature lived in the fort for 118 years. It died in 1918 when it became blind and accidentally fell to its death from atop a gun turret.

The Seychelles giant tortoise is one of the only two tortoise species in existence that has been observed committing homosexual acts. [6]

Morphotype

This is a controversial subspecies possibly distinct from the Aldabra giant tortoise. The species is a morphologically distinctive morphotype, but is considered by many researchers to be either synonymous with or only subspecifically distinct from that taxon. This identification is based primarily on morphological characters. Published molecular identifications are unclear with several different indications provided by different data sources. [7]

It is a domed grazing subspecies, differing from the Aldabra tortoise in its broader shape and reduced ossification of the skeleton; it differs also from the other controversial giant tortoise in the Seychelles, the saddle-backed morphotype (Arnold's giant tortoise).

It was apparently extirpated from the wild but is now known only from 37 adults, including 28 captive, and 8 on Cousine Island, 6 of which were released in 2011 along with 40 captive-bred juveniles. Captive-reared juveniles show that there is a presumed genetic basis to the morphotype and further genetic work is needed to elucidate this. [8] [9] [10]

Extinction and rediscovery

Originally, several different subspecies of giant tortoise inhabited the Seychelles. Large and slow, the tortoises were reportedly friendly, with little fear of man. Sailors and settlers slaughtered thousands and swiftly drove most populations to extinction.[ citation needed ]

Though generally assumed that the Aldabra giant tortoise was the only one to have survived over-exploitation in the Seychelles, it is occasionally, most recently in 1995, suggested that some Seychelles granitic island tortoises survived in captivity. The report of oddly shaped captive tortoises prompted the Nature Protection Trust of Seychelles to examine the identity of the living tortoises. Examination of museum specimens of the 'extinct' Seychelles subspecies by Dr. Justin Gerlach and Laura Canning confirmed that some living tortoises exhibited characteristics of the supposedly extinct subspecies. [11] Some recently[ when? ] published scientific papers on the genetics of the Seychelles and Indian Ocean tortoises provide conflicting results.[ citation needed ] Some studies suggest only one species (with multiple variants) was ever present in the islands, whilst others suggest three distinct, but closely related species. These different views derive from studies of different genes.[ citation needed ]

Conservation

A baby and a possibility for the reestablishment of this subspecies Young dipsochelys hololissa.jpg
A baby and a possibility for the reestablishment of this subspecies

With DNA testing, tortoises of the "extinct" subspecies were identified and acquired by the Nature Protection Trust of Seychelles for conservation. They were brought to Silhouette Island and the captive-breeding program was initiated in 1997. For several years the female tortoises produced infertile eggs. In November 2002 eggs laid by a young female started to hatch. [12] By the time the Nature Protection Trust of Seychelles was evicted, they had produced 40 juveniles of the Seychelles giant tortoise. [8] [9] [13]

The decision of the Islands Development Company to evict the Nature Protection Trust of Seychelles from Silhouette island by March 2011, and their refusal to permit wild tortoises to live on the island forced them to remove and find new homes for the tortoises.

The privately managed island of Cousine agreed to provide a new home for the Seychelles tortoises. [2] In April 2011, the Seychelles giant tortoises went to Cousine. [2] If they had been able to release them on Silhouette island, they would have established a separate wild population, now they will be mixed with the Aldabra tortoises that are already on Cousine island. [2] The Nature Protection Trust of Seychelles takes consolation from producing a new generation of many young tortoises which will live for at least 100 years. In that time there may be an opportunity to establish pure populations of these tortoises. These animals live longer than short-term management and development perspectives. [10]

Related Research Articles

Geography of Seychelles

The Seychelles is a small island nation located in the Somali sea northeast of Madagascar and about 835 mi (1,344 km) from Mogadishu, Somalia, its nearest foreign mainland city, while Antsiranana is the nearest foreign city overall. Seychelles lies between approximately 4ºS and 10ºS and 46ºE and 54ºE. The nation is an archipelago of 115 tropical islands, some granite and some coral. the majority of which are small and uninhabited. The landmass is only 452 km2 (175 sq mi), but the islands are spread wide over an Exclusive Economic Zone of 1,336,559 km2 (516,048 sq mi). About 90 percent of the population of 90,000 live on Mahé, 9 percent on Praslin and La Digue. Around a third of the land area is the island of Mahé and a further third the atoll of Aldabra.

Tortoise Family of turtles

Tortoises are reptile species of the family Testudinidae of the order Testudines. They are particularly distinguished from other turtles by being land-dwelling, while many other turtle species are at least partly aquatic. Like other turtles, tortoises have a shell to protect from predation and other threats. The shell in tortoises is generally hard, and like other members of the suborder Cryptodira, they retract their necks and heads directly backwards into the shell to protect them.

Aldabra Coral atoll in the Indian Ocean

Aldabra is the world's second-largest coral atoll. It is situated in the Aldabra Group of islands in the Indian Ocean that are part of the Outer Islands of the Seychelles, with a distance of 1,120 km (700 mi) southwest of the capital, Victoria, on Mahé Island.

Giant tortoise Reptile

Giant tortoises are any of various large land tortoises formerly common on the islands of the western Indian Ocean and on the Galápagos Islands.

Aldabra giant tortoise species of reptile

The Aldabra giant tortoise, from the islands of the Aldabra Atoll in the Seychelles, is one of the largest tortoises in the world. Historically, giant tortoises were found on many of the western Indian Ocean islands, as well as Madagascar, and the fossil record indicates giant tortoises once occurred on every continent and many islands with the exception of Australia and Antarctica. Many of the Indian Ocean species were thought to be driven to extinction by over-exploitation by European sailors, and they were all seemingly extinct by 1840 with the exception of the Aldabran giant tortoise on the island atoll of Aldabra. Although some remnant individuals of A. g. hololissa and A. g. arnoldi may remain in captivity, in recent times, these have all been reduced as subspecies of A. gigantea.

Radiated tortoise species of reptile

The radiated tortoise is a species in the family Testudinidae. Although this species is native to and most abundant in southern Madagascar, it can also be found in the rest of this island, and has been introduced to the islands of Réunion and Mauritius. It is a very long-lived species, with recorded lifespans of at least 188 years. These tortoises are classified as critically endangered by the IUCN, mainly because of the destruction of their habitat and because of poaching.

Adwaita was a male Aldabra giant tortoise that lived in the Alipore Zoological Gardens of Kolkata, India. At the time of his death in 2006, Adwaita was believed to be amongst the longest-living animals in the world.

Cousine Island island

Cousine Island is a small granitic island 30 ha in the Seychelles 6 km (4 mi) west of Praslin Island. It is a combination luxury resort and since 1992 a nature preserve.

<i>Aldabrachelys</i> genus of reptiles

Aldabrachelys is the recognised genus for the Seychelles and Madagascan radiations of giant tortoises, including the Aldabra giant tortoise.

Galápagos tortoise Species of reptile

The Galápagos tortoise complex or Galápagos giant tortoise complex are the largest living species of tortoise. Modern Galápagos tortoises can weigh up to 417 kg (919 lb). Today, giant tortoises exist on only two remote archipelagos: the Galápagos Islands 1000 km due west of mainland Ecuador; and Aldabrachelys gigantea of Aldabra in the Indian Ocean, 700 km east of Tanzania.

White-throated rail Species of bird

The white-throated rail or Cuvier's rail is a species of bird in the family Rallidae. It is found in Comoros, Madagascar, Mayotte, and Seychelles. A flightless subspecies, Dryolimnas (cuvieri) aldabranus, inhabits Aldabra, while a semi-flightless subspecies D. c. abbotti, from Assumption went extinct in the early 20th century due to introduced predators. A fourth extinct flightless subspecies or descendant species is known from fossil remains on Aldabra, and anatomically was almost identical to the Aldabra rail. This subspecies was wiped out by rising sea levels during the Pleistocene, but the atoll was recolonized by the white-throated rail after it resurfaced; this population evolved in a very similar way to the extinct subspecies, eventually evolving into the modern Aldabra rail. This is one of the very few observed instances of iterative evolution, in which a distinct population is wiped out from an area but it is recolonized by members of the source population, who evolve in the same way as the extinct population.

Réunion giant tortoise species of reptile

The Reunion giant tortoise was an extinct species of giant tortoise in the family Testudinidae. It was endemic to Réunion Island in the Indian Ocean.

<i>Cylindraspis</i> genus of reptiles

Cylindraspis is a genus of recently extinct giant tortoises. All of its species lived in the Mascarene Islands in the Indian Ocean and all are now extinct due to hunting and introduction of non-native predators.

Saddle-backed Rodrigues giant tortoise species of reptile

The saddle-backed Rodrigues giant tortoise was an extinct species of giant tortoise in the family Testudinidae. The species was endemic to Rodrigues. Human exploitation caused the extinction of this species around 1800.

Wildlife of Seychelles

The Wildlife of Seychelles comprises the flora and fauna of the Seychelles islands off the eastern coast of Africa in the western Indian Ocean.

Jonathan (tortoise) Male Seychelles giant torito

Jonathan is a Seychelles giant tortoise, a subspecies of the Aldabra giant tortoise, and the oldest known living terrestrial animal in the world. Jonathan resides on the island of Saint Helena, a British Overseas Territory in the South Atlantic Ocean.

<i>Aldabrachelys grandidieri</i> species of reptile

Aldabrachelys grandidieri, or Grandidier's giant tortoise, is an extinct species of tortoise that was endemic to Madagascar. Mitochondrial DNA extracted from subfossil bone confirm that it is a distinct species.

<i>Aldabrachelys gigantea arnoldi</i> subspecies of reptile

Arnold's giant tortoise, also known as the Seychelles saddle-backed giant tortoise, is a tortoise subspecies in the genus Aldabrachelys.

François Leguat Giant Tortoise and Cave Reserve

François Leguat Giant Tortoise and Cave Reserve is a park and nature reserve on the island of Rodrigues, dedicated to protecting the fauna and flora of the island. The reserve first opened in August 2007, part of the same project as La Vanille Reserve in Mauritius. It is named after the 18th century Huguenot settler François Leguat, who recorded much of the island's natural flora and fauna before it went extinct. The reserve includes a museum, several education centres and information areas, and a restaurant.

Giant tortoises are any of various large land tortoises

References

  1. Aldabrachelys gigantea at the Reptarium.cz Reptile Database. Accessed 05 June 2015.
  2. 1 2 3 4 "Moving giant tortoises" . Retrieved 5 June 2015.
  3. "The identification of Seychelles giant tortoises" . Retrieved 5 June 2015.
  4. BBC News - South Asia (2006-03-23). "'Clive of India's' tortoise dies". BBC News . BBC Online . Retrieved 2014-01-23.
  5. Kettle, Sally (13 March 2014). "Meet Jonathan, St Helena's 182-year-old giant tortoise". BBC News . Archived from the original on 2014-04-09.
  6. https://nypost.com/2017/10/19/turns-out-this-186-year-old-tortoise-has-a-gay-lover/amp/
  7. "Release of Arnold's giant tortoises Dipsochelys arnoldi on Silhouette island, Seychelles; By Justin Gerlach" (PDF). Retrieved 7 June 2015.
  8. 1 2 "Tortoises" . Retrieved 6 June 2015.
  9. 1 2 "Tortoise reintroduction" . Retrieved 5 June 2015.
  10. 1 2 "Aldabrachelys hololissa, 061" . Retrieved 7 June 2015.
  11. "Giant tortoises" . Retrieved 5 June 2015.
  12. "Hatchings" . Retrieved 7 June 2015.
  13. "Tortoise news" . Retrieved 7 June 2015.