Archive for Adamsiella jarvisi
Biodiversity is one of those buzz-words bounced around in the media when hailing the discovery of new species or bemoaning the loss of those species from global warming and other human-induced changes to the environment. To scientists biodiversity is the holy grail of scientific disciplines. Simply put, biodiversity relates to the variation of living organisms found within an ecosystem. And the health of an ecosystem can be measured from datum derived from biodiversity research.
Jamaica may be the biodiversity capital of the world. Much of the flora and fauna of the island is endemic, meaning it is found no where else in the world. The terrestrial mollusks (snails) are a fascinating group of living organisms to study island endemism. Most of the 500+ species of terrestrial snails are endemic to Jamaica; many are found only in narrow niches. Why is this important?
Consider this — a snail with a geographical distribution of only a few square miles can become extinct if its habitat is altered or wiped out through deforestation by farming or strip mining. In Jamaica, the reasons for habitat destruction are numerous, but not unique to the island. Deforestation is a story for another time on another Blog.
In the coming days, I will post pictures of many endemic snail species known only from small micro-habitats around Jamaica. The beautiful and exotic shapes and forms of these species belie the earthy and often harsh environments that these molluscan species inhabit. Getting to these remote habitats sometimes involves long treks through muddy rain forests fraught with insects and stinging foliage. The reward for enduring such hazards is contact with the natural beauty of Jamaica’s flora and fauna — a part of Jamaica that most people never experience when staying at coastal resort enclaves.
Among the fascinating snails found only in a small swath of territory Jamaica’s central Parishes of Clarendon and St. Catherine is the operculate snail, Adamsiella jarvisi. Operculates are classified as prosobranch, meaning the anatomical arrangement of the gills is forward of the heart. Most of the sea snails and all of the operculate terrestrial snails are prosobranch. The operculate snails on terra firma have evolved a trap door or operculum to protect the snail when withdrawn into its shell.
Adamsiella jarvisi is a small ± 10 millimeter (mm) size species that lives on limestone rock. It is often found aestivating (a form of short-duration hibernation) while attached to a rock face with the spire hanging in a downward direction. The operculum is affixed to the foot of the snail (the small thickened circular white disk visible on the back of the snail’s foot in the photograph above). When disturbed or threatened by a predator, the snail withdraws into the shell and the hard, calcarious operculum seals the snail into the shell. Snail predators include beetles and birds. More than half of Jamaica’s endemic terrestrial mollusks are operculate snails.
Stay tuned for more terrestrial trackings from Jamaica.