Description
The Green Turtle can reach 1.5 m carapace length but is typically
less than 1
m. It is characterized by a broad and flattened carapace with no keel and only
slight
serrations along the back edge. It is olive to brown or black in
colour and may be mottled. The plastron
is clear white or yellowish. The skin is brown or grey to black
and the paddle-like forelimbs have only one claw which is long and
curved in males. Males also have prehensile tails with a flattened
nail at the tip. Green Turtles can be distinguished from other
seas turtles by their four costal scutes
the first of which does not touch the nuchal scute and the pair of prefontal
scales
between the eyes.
Confusing Species
The Green Turtle is similar to the other hard-shelled
sea turtles and is intermediate in size between the Loggerhead Turtle and the Atlantic Ridley Turtle. Both of the
other
turtles have coarse serrations along the back edge of the carapace and sculpting along the
centre line
-- a keel in the Loggerhead Turtle and five raised knobs in the
Atlantic Ridley. The shape of the carapace also differs.
Distribution
Green Turtles are found in both the Atlantic and
Pacific oceans. In Canada they have been seen on the west coast of
Vancouver Island. Their distribution on the Pacific coast is
influenced by El Nino weather events. It ranges throughout
tropical portions of the Atlantic, Pacific and Indian oceans.
Habitat
Although it has been seen up to 160 km from land and
can migrate across 2,000 km of open ocean feeding occurs in water
as little as 3-5 m deep. Reefs and rocky areas are used for
resting. Hatchlings may use floating mats of sargassum algae.
Nesting occurs on flat continental or island beaches with little
wave action.
Reproduction
Green Turtles may take from 19-24 years to reach sexual
maturity. Nesting in Pacific populations occurs in winter or
spring on beaches in areas such as Hawaii, Mexico and central
America. Most females breed every three years and lay several
clutches of up to 238 eggs. Hatchlings from a nest emerge together
after dark. Sex of hatchlings is determined by incubation
temperature.
Natural history
The Green Turtle is the only sea turtle that commonly
leaves the water to bask although they also bask on the surface of
the water -- sometimes providing a landing site for seabirds.
Adult Green Turtles prefer to feed on algae or sea grasses while
juveniles eat a variety of invertebrates.
Conservation Concerns
Green Turtles and their eggs have long been harvested
by humans for food and are an important source of protein in some
third world countries. Populations have declined dramatically over
the last 50 years although not to the same degree as other species
of marine turtles. Other threats to the species are exploitation
of the nesting and feeding grounds.
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