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| This snail, in the family Succineidae, is endemic to St
Helena. It gives the impression of being too big for its shell. There
are only a few whorls and they increase rapidly in size, so that the spire
is short but pointed and the aperture very large (up to three quarters
of the total length). The snails grow to a maximum of only 12 mm long
by 9 mm wide. The shell is glossy and the colour varies from pale amber
to golden brown; the blushing effect is caused by light striking through
the translucent body and shell. Populations in different parts of St Helena
are very different in shell shape and colour, varying from swollen animals
with enormous apertures on the humid central ridge to more compressed
types from dry areas such as Horse Point Plain. In the 19th century many
of these variants were considered to be separate species, but they prove
to have consistent internal anatomy, so they are all considered as one
species. The Blushing Snail has no close relatives in Africa or elsewhere
and is evidently derived from an ancient colonisation, probably by means
of eggs or young individuals carried accidentally by aquatic birds such
as Moorhens. Unlike most of the other endemic snails, this species has survived the drastic ecological changes on the island and is abundant in many habitats at middle and high levels. On the central ridge it may even have benefited from the extinction of some of its endemic competitors, although in drier areas it has presumably suffered from the reduction of vegetation. |
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