Few creatures embody the spirit of the oceans
to such an extent as the turtle; a graceful, gentle, glorious creature,
drifting at the whim of the tides and currents. These marvellous beasts are
some of nature's finest creations - the physical personification of beauty.
Green
Sea Turtles are amongst the most well known sea creatures, growing to lengths
of 1.5 metres and amassing weights of up to 240 kilograms - making them the
second-largest species of the turtle family.
A
common misconception concerning the green sea turtle is the etymology of its
name; whilst many would assume that the species derives its name from the
colouring of its shell, this is, in fact, false. Green Sea Turtle shells range
in colour from the famous olive green to darker shades and even the
idiosyncratic black-shelled specimen. Their name is in fact derived from the
green pigment of the fat beneath its
shell, otherwise known as the subdermal body fat. Thus, the Pacific Black
Turtle is actually a misidentified variation of the Green, the darker
colouration of its shell being the only differentiation between the two.
As with almost all turtle species -
Leatherback Turtles being the only exception - the Green Sea Turtle is
possesses a hard carapace, or shell, comprised of large scutes, or shell
plates. These scutes are arranged with four costal, or lateral, plates along
the edges of the shell. Another important feature, endemic to Green and
Flatback Turtles, is the number of prefrontal scales - the scales found in
front of its eyes. Whilst the majority of turtle species have two pairs, only
one pair is present in the aforementioned species. This leaves the Green Sea
Turtle appearing almost identical to the Flatback Turtle, but with one final
differentiation: a Green Sea Turtle's carapace is oval and smooth, the Flatback
Turtle's has slightly upturned edges - a distinct differentiation. Green Sea
Turtles colourations, as described before, range from olive green to brown and
black on the carapace, with green subdermal body fat and a pale yellow
plastron, or underside.
One
of the more widely-distributed turtle species, Green Sea Turtles can be found
inmost tropical waters, such as the Caribbean and Mediterranean Seas as well as
the Atlantic, Indian and Pacific Oceans. Over eighty countries host turtle
nesting beaches, which are frequented between three and five times a year
between pelagic migrations. Generally, Green Sea Turtles will remain in coastal
areas - although females often make vast migrations to nesting sites, with one
known group of turtles travelling an immense 2,300 kilometres from the coast of
Brazil to the South Atlantic Ascension Island.
Provided
they evade death at the hands of human hunters or the jaws of marine predators,
Green Sea Turtles, as with the majority of turtle species, can live for up to
100 years. Despite this longevity, however, Green Sea Turtles take between 20
and 50 years to reach sexual maturity. This, combined with the minute survival
rate of hatchlings, results in wavering reproduction rates - greatly worsened
by the presence of hunters and egg-stealers in coastal areas and on nesting
beaches.
Green
Sea Turtles reproduce at spasmodic intervals; females reproduce only every two
or three years, nesting between three and five times per nesting season and
laying in each nest an average of 115 eggs, which incubate for 60 days under
the sand of ancestral nesting beaches. Turtles will always return to the
nesting beaches upon which they hatched, which makes migration tracking far easier
for marine biologists with satellite tags.
As
juveniles, Green Sea Turtles consume a wide array of plant and animal life,
ranging from seagrass to crustaceans, jellyfish and squid. In adulthood,
specimens tend to become herbivores, surviving off of seagrass and algae. Some
adult turtles have been known to prey on squid and jellyfish as well, although
this is not the general pattern.
Tragically,
Green Sea Turtles, as with a myriad of marine species, are endangered due to
human interference in their habitats. Seagrass destruction jeopardises their
food chains, whilst construction on nesting beaches often destroys eggs and
prevents females from nesting. A rapidly expanding demand for turtle shells is
yet another example of human greed driving nature into extinction. This,
combined with the natural fluctuation in Green Sea Turtle reproduction, brings
them dangerously close to the brink of the mire of extinction - a predicament
from which they must be rescued at all costs.
Bibliography
Daniel Bailey
Sunday 7th of February 2016, 11:09 GMT
England
Dedicated to Beth, Andrew, Lauren, Sanye, Demy and Claire at London Sea Aquarium - thank you for reminding me how much I loved marine biology.
Dedicated to Beth, Andrew, Lauren, Sanye, Demy and Claire at London Sea Aquarium - thank you for reminding me how much I loved marine biology.
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