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JAMAICA,
SNAIL PARADISE
A
Creole land, former English colony and home of the Rasta culture, many
groups of "Maroons" (fugitive slaves), a growing tourism industry
and the most interesting thing, over 600 different species of landsnails,
most found nowhere else in the world.
The
colonial times are gone but the taste of this past is always present.
Famous during centuries as the banana capital of the world, for the
aromatic Blue Mountain coffees and as a retirement place for aristocracy
and rich people, it's a place where to find Great Houses, luxuriant
forests on karstic formations and beautiful sunsets over seas of deep
blue colour.
A
treasure for naturalists
People
came sailing or by steamers to Montego Bay to spend the winters out
of home, to run a plantation in a tropical island, or just to see the
luxuriant landscapes of this Antillean island; but much before it attracted
the interests of first amateur and later professional naturalists and
scientists; the plant diversity was found astonishing, being the orchids
a favourite with hundreds of species, insects and later molluscs found
the attention of scholars as C.B.Adams and Chitty, who made a large
work on the molluscan fauna of this island. Later on, H.B.Baker and
other authors have been giving aditions to the previous surveys.
Being
such a small island nowhere else in the world is found such an amount
of land dwelling prosobranchs compared to it's entire molluscan fauna
(a reason for this might be the colonization of this island by just
a few groups of snails, many being prosobranchs, giving the chances
for them to choose between the different unoccupied habitats found,
these are the ancestors of species we find). So this high degree of
endemicism makes this island one of the "hot spots" of molluscan
diversity.
There
are supposed to be many reasons for these happenings that allowed the
radiation, the isolation of the island since supposed Miocene times,
and added to this that the climatical and geological conditions are
the best for this animal groups, mixing all this, you get someway a
Galapagos like island, where not just molluscs but also reptiles and
plants are one of a kind species.
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The
karstic geology
Understanding
the geological past is important, Jamaica is mainly composed of a small
mass of igneous rocks surrounded by limestone, this last formed in marine
conditions, which shows in over 75% of the territory.
For
landsnails these limestone areas covered in jungle are perfect for making
a living, first for their need for a large amount of calcium carbonate
for building up their shell as other metabolical reasons, and as important
the stone melts down due to the CO2 dissolved in the water it creates
crevices and holes, perfect for hidding away from other predators looking
for food as well as a good hide away during dry times.
Travelling
around Jamaica is like visiting a large cave system, specially in the
area called the "Cockpit Country" where in fact a large cave
system is found; anyone can appreciate the wonders of the karstic landscape,
large limestone haystack knolls surrounded by valleys for miles, all these
areas are the homes for these extraordinary animals..
The
high degree of endemicism, as said, is associated to geographical isolation
, a local example, as the limestone hills melt down it is more difficult
to every population of one species to meet members of other populations,
locked to other hills, so differences begin to grow, as every species
goes on in it's own process of evolution, then genetical isolation begins,
slight differences are changing the characters of the species and possibly
making it difficult for succesful encounters within these different populations
in the future. So what we get, different but closely related species in
every hill or valley.
Being an island it is also possible to perceive affinities with members
of similar families of snails of the Greater Antilles (as Hispaniola and
Cuba for example) and Central America. This shows there was a flow of
animals coming from that way so a connection might have existed in the
past within these areas, later on it dissapeared (Miocene?) and the species
diverged from their original forms to the varieties we can found today.
There
are not many species found living all around the island, mainly these
are introduced (as Orthalicus undatus) or came associated to human
activities, anywhere you go you are most likely to encounter different
endemics in every different site at the species level or at least forms
or subspecies.
The
problems often arise when you are supposed to move in this karstic enviroment,
there are places where no human intervention has been known... muddy trails,
high limestone walls, deep pits, have been keeping the secrets of this
land away from foreigners.
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