Rhachistia aldabrae | |
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Drawing of the shell of Rhachistia aldabrae | |
Scientific classification | |
Kingdom: | Animalia |
Phylum: | Mollusca |
Class: | Gastropoda |
Subclass: | Heterobranchia |
Order: | Stylommatophora |
Family: | Cerastidae |
Genus: | Rhachistia |
Species: | R. aldabrae |
Binomial name | |
Rhachistia aldabrae (von Martens, 1898) [2] | |
Synonyms | |
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Rhachistia aldabrae, the Aldabra banded snail, is a species of air-breathing land snail, a pulmonate gastropod mollusc in the family Cerastidae. The species lives on one atoll in the Seychelles Islands, Indian Ocean, and is easily recognizable for its purplish-blue banded shell. The species was thought to have died out because of climate change, [3] but was rediscovered in 2014.
The shell of this snail is very unusual in its coloring: purple, indigo blue, and orange, and this makes the snail very easy to recognize and identify. The Aldabra snail grazes on algae, and thus it is very low on the food chain. [4]
The shell of this species is oblong, ovate-conical, rather thick, slightly striated, glossy, in the upper part is pale, in the lower part it is black brown. [2] The shell has seven slightly curved and regularly increasing whorls. [2] The upper 3-4 whorls are blackish, the following are dim bluish. [2]
The Aldabra banded snail is endemic to Aldabra Atoll in the Indian Ocean. In 1906 it was the most common snail species on the atoll. [5] [6]
After 1976 however, only adult snails were found on Aldabra, and no live individuals had been found at all between 1997 and August 2014. [3] Researchers had believed that this species became extinct during the late 1990s, after a series of unusually long, hot, and dry summers caused by climate change. These summers appear to have killed off a large number of the younger snails. [7]
The habitat of this snail suffered a sudden decline in rainfall in the 1990s, which was essential to the survival of this species, and this dryness appeared to have caused its extinction. Living snails were discovered on 23 August 2014. [8] [9] [10] [11]
A number of specimens of the snail were discovered on August 23, 2014. A team of Seychelles Islands Foundation (SIF) staff were exploring infrequently visited parts of Malabar Island, the second largest island of Aldabra, when the snails were found. Dr Frauke Fleischer-Dogley, CEO of the CIF, commented: [8] [12]
The re-discovery of the Aldabra banded snail provides a beacon of hope. Despite major global environmental threats like climate change, this discovery shows that investments into protecting unique island biodiversity are well-placed. This snail provides hope for other island species, of which we have already lost too many. I hope that those of the international community, who are meeting at the Third International Conference on Small Island Developing States, take note that their investment is needed to generate such success. Nature has a resilience that may surprise us.
Seychelles, officially the Republic of Seychelles, is an archipelagic state consisting of 115 islands in the Indian Ocean. Its capital and largest city, Victoria, is 1,500 kilometres east of mainland Africa. Nearby island countries and territories include the Comoros, Madagascar, Mauritius, and the French overseas departments of Mayotte and Réunion to the south; and Maldives and the Chagos Archipelago to the east. It is the least populated sovereign African country, with an estimated 2020 population of 98,462.
Seychelles is a small island country located in the Sea of Zanj due north of Madagascar, with Antsiranana as its nearest foreign city. 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.
Aldabra is the world's second-largest coral atoll, lying south-east of the continent of Africa. It is part of 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 tortoises are any of several species of various large land tortoises, which include a number of extinct species, as well as two extant species with multiple subspecies formerly common on the islands of the western Indian Ocean and on the Galápagos Islands.
The Aldabra giant tortoise is a species of tortoise in the family Testudinidae. The species is endemic to the Seychelles, with the nominate subspecies, A. g. gigantea native to Aldabra atoll. It 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.
Cosmoledo Atoll is an atoll of the Aldabra Group and belongs to the Outer Islands of the Seychelles, and is located 1,029 km (639 mi) southwest of the capital, Victoria, on Mahé Island.
The Aldabra brush warbler is an extinct bird in the acrocephalid warbler family. It was endemic to the atoll of Aldabra in the Seychelles and an individual was last seen in 1983.
The white-throated rail or Cuvier's rail, is a species of bird in the family Rallidae.
The Reunion giant tortoise is an extinct species of giant tortoise in the family Testudinidae. It was endemic to Réunion Island in the Indian Ocean.
The Aldabra flying fox is a species of megabat in the genus Pteropus. It is endemic to the Aldabra Atoll in the Seychelles, like Chaerephon pusilla, though the latter may be the same species as the little free-tailed bat.
The Wildlife of Seychelles comprises the flora and fauna of the Seychelles islands off the eastern coast of Africa in the western Indian Ocean.
Aldabrachampsus is an extinct genus of small horned crocodile known from fragmentary remains. It lived during the Pleistocene on Aldabra Atoll, Seychelles in the western Indian Ocean. The name Aldabrachampsus dilophus means "Two-crested crocodile from Aldabra". It was a small animal, reaching a length of 2–2.5 m, comparable in size to the smallest extant crocodilians.
Opisthostoma vermiculum is a species of minute land snail with an operculum, a terrestrial gastropod mollusk or micromollusk in the family Diplommatinidae. The shell possesses four different coiling axes; the most for any known living gastropod. This member of the Diplommatinidae family is endemic to Malaysia. Its natural habitat is tropical limestone outcrops.
Rhachistia is a genus of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the family Cerastidae.
Clavus auriculifera is a species of sea snail, a marine gastropod mollusk in the family Drilliidae.
Pleuroploca trapezium, common name : the trapezium horse conch or striped fox conch, is a species of sea snail, a marine gastropod mollusk in the family Fasciolariidae, the spindle snails, the tulip snails and their allies.
Harpago arthriticus, common name : the arthritic spider conch, is a species of sea snail, a marine gastropod mollusk in the family Strombidae, the true conchs.
Edentulina moreleti is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Streptaxidae.
Arnold's giant tortoise, also known as the Seychelles saddle-backed giant tortoise, is a tortoise subspecies in the genus Aldabrachelys.
The Seychelles giant tortoise, also known as the Seychelles domed giant tortoise, is a tortoise subspecies in the genus Aldabrachelys.
This article incorporates public domain text from the reference. [2]