Aldabra banded snail
|Aldabra banded snail|
|Drawing of the shell of Rhachistia aldabrae|
|Species:||† R. aldabrae|
|† Rhachistia aldabrae
(von Martens, 1898)
The †Aldabra banded snail, scientific name Rhachistia aldabrae, was a species of air-breathing land snail, a pulmonate gastropod mollusc in the family Cerastidae. The species lived on one atoll in the Seychelles Islands, Indian Ocean, and was easily recognizable because of its purplish-blue banded shell. The species is thought to have died out because of climate change.
The shell of this snail was very unusual in its coloring: purple, indigo blue, and orange, and this made the snail very easy to recognize and identify. The Aldabra snail grazed on algae, and thus was very low on the food chain.
The shell is oblong, ovate-conical, rather thick, slightly striated, glossy, in the upper part is pale, in the lower part it is black brown. The shell has seven slightly curved and regularly increasing whorls. The upper 3-4 whorls are blackish, the following are dim bluish.
After 1976 however, only adult snails were found on Aldabra, and no live individuals have been found at all since 1997. Researchers believe 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.
Cause of extinction
The habitat of this snail suffered a sudden decline in rainfall, which was essential to the survival of this species, and this dryness appears to have caused its extinction.
This article incorporates public domain text from the reference.
- Gerlach J. (2006). "Rhachistia aldabrae". In: IUCN (2009). IUCN Red List of Threatened Species. Version 2009.2. <www.iucnredlist.org>. Downloaded on 18 February 2010.
- (German) von Martens E. & Wiegmann F. (1898). "Land- und Süsswasser-Mollusken der Seychellen nach den Sammlungen von Dr. Aug. Brauer." Mitteilungen aus der Zoologischen Sammlung des Museums für Naturkunde in Berlin 1: 1-94. page 28, table 2, figures 15-16.
- Gerlach, J. (2007). "Short-term climate change and the extinction of the snail Rhachistia aldabrae (Gastropoda: Pulmonata)". Biology Letters 3 (5): 581–584. doi:10.1098/rsbl.2007.0316. PMC 2391199. PMID 17666376.
- http://news.mongabay.com/2007/0813-snail.html, Climate Change Claims a Snail, Rhett A. Butler, Mongabay, 2009, 10/21/09.
- Smith M. (October 1909) "The land Mollusca on Aldabra". The Nautilus 23(5): 69-70.
- van Brugge A. C. (17 September 1975) "Streptaxidae from Aldabra Island, Western Indian Ocean". Bulletin of the British Museum (Natural History), 28(5): 157-175. page 171.
- Jacquot J. E. (August 2007) "Is the Aldabra Banded Snail the First Global Extinction Related Extinction." www.treehugger.com (Science and Technology), accessed 14 October 2009.
- Photos of shells of this species (Note: there are spelling errors on the page.)