Marine Turtles
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Turtle on Yonge Reef.
Photo: V. Harriot
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Marine turtles (or sea turtles) are some of the more conspicuous animals
in the Great Barrier Reef World Heritage Area. As well as being of importance
to the tourism industry (turtle watching), turtles have spiritual and
social importance to Australia's indigenous peoples.
Turtles are reptiles like crocodiles, alligators, snakes and lizards.
Their land living relatives are tortoises, of which there are 37 living
species, although none live in Australia. There are 181 species of freshwater
turtles of which 20 are found in Australia. Fresh water turtles are smaller
than marine turtles (15-45cm), and have webbed feet allowing them to be
mobile in water and on land.
Marine turtles can live for 60 years or more and are well adapted to
life in the sea. They can spend up to half an hour underwater, before
coming to the surface to breath air. Their forelimbs are strong paddle
shaped flippers, with which they flap bird-like as they cruise around
the reef. Each Australian species has their favoured food. They drink
salt water, but exude the excess salt through glands next to their eyes.
Turtles are 30 years old or more before they start to breed. Males and
females migrate from feeding grounds to breeding grounds during the summer
breeding season. Turtles mate in the water; the male mounting the female
and holding on to her carapace with spurs on his flippers. A female can
mate with several males and store sperm for successive batches of eggs.
Having mated, the males return to their feeding grounds. Meanwhile the
females stay in the breeding grounds going on shore at night at about
fortnightly intervals to lay several clutches. Females lay their clutch
of leathery ping-pong shaped eggs on land.
All six species of Australian marine turtles are protected under the
National Parks and Wildlife Conservation Act 1975.
CRC Reef research on marine turtles includes management of green turtles
and the survivorship of turtles after capture in trawls.
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