General Category | 14-03-08 03:56 GMT | Posted by Ian Chicken
Reptiles:- The Green turtle
The
Green Turtle is probably the best known symbol of
Ascension Island.
It
was Peter Mundy in 1656 who made the first notes on the subject when the ship he
was on visited Ascension.
They captured several of them and he made notes of his observations. These notes
included the adults, young and the nesting process. Of the Nesting he wrote
"Aboutt the iland are many baies and coves, where the sea-tortoises com on
shore to lay their eggs, which they doe by night and scraping a pitt in teh
sand, doe lay their eggs in itt, and soe covering them againe, leave them to be
hatched and brought forth by the heatt of the sun"
He went on to describe how the young hatch out and find their way to the
water
"The yong ones, as soone as they are hatched, run toward the sea by instinctt
of nature"
Since a vast amount of research has been completed or is still being
collected on the subject of these reptiles.
The Ascension turtle comes from the Brazilian coastal areas feed on algae that
is on the seabed, and then at intervals of a few years, migrate to the island,
always returning to the same beach to lay their eggs.
The
young if they survive the hazardous trip in the first few days spend the first
few years of the lives moving around a the south atlantic. At this stage they
are carnivores feeding off
the likes of jellyfish.
Once they are large enough to fend of any predators they change their life style
and become herbivores feeding of the algae.
Little is known of how they do manage to find there way over large distances
with such accuracy. Suggestions on how the do it range from the magnetic fields
of the earth to smell in the oceans.
Green turtles have a carapace (shell) that can reach 140cm in length.
The carapace has five plates in the middle with four plates on each side.
When
they arrive at Ascension island they will mate, which can take a few days to
complete. When the female is ready, she will come ashore at night and dig a
large pit in the sand. once this has been formed she will then dig out a chamber
that is cylindrical in shape and about 60cm deep.
She will then lay her eggs (this is about 120 in total, and can be 3 or 4
clutches in a season) in this chamber filling it to about 50% of its depth. Once
completed she will then fill the rest of it in, after which the pit she has dug
is also filled in.
The
eggs are white in colour, and about the size of a ping pong ball (45mm
approximately).
incubation of the eggs takes about 60 days, being warmed by the sun on the damp
sand. The temperature is a major factor in what happens to the young as far as
sexing is concerned. with cooler sand the young are likely to be male, with
warmer producing the females the central point at which an even split of sex is
produced is 29ºC.
Due to the to the differing beaches on Ascension the sex can be mostly
determined, the lighter coloured beaches are cooler than the darker ones.
Therefore Long Beach will produce Males and the beaches to the north east the
females.