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Hawksbill Sea Turtle
Eretmochelys imbricata
Habitat and Biology:
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| illustration: M. Demma
© ICRAM |
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Typical habitats:
- Favour clear, relatively shallow water of coastal reefs, bays,
estuaries and lagoons.
Migrations:
- Recapture of juveniles suggest that some do not migrate.
- They are, however, records of long migration in some areas
e.g. nesting sites of Nicaragua to Jamacia, from Northern Australia
to Papua New Guinea.
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Nesting areas:
- Generally nests alone or in small groups so reducing the effects
of egg poaching.
Nesting periods:
- Late spring and summer, nest every 2 or 3 years.
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| illustration: M. Demma
© ICRAM |
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Nesting behaviour:
- Lays several times in the season; mean 2 - 3, range 1 - 54
eggs
- Normally females nest at night though daytime nesting occurs
in West Indian Islands
- A fairly agile turtle, it is able to scramble over rocks and
roots to nest in the shade of vegetation. A feature peculiar
to this species.
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Egg number, size and weight:
- Clutch size mean 150 (range 70 - 250) varies with area.
- Egg Size: Length 30 - 45 mm; Mass 20 - 31.6 g
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| illustration: M. Demma
© ICRAM |
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Size and weight of hatchlings:
- Length SCL38 - 46 mm
- Mass 8 - 17.6 g
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Incubation time:
- Incubation time: 47 - 75 varying with place and point in the season
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| illustration: M. Demma
© ICRAM |
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Maturity:
- Uncertain but females 68 - 80 cm (SCL) long
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| illustration: M. Demma
© ICRAM |
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Courtship and Mating:
- Observed mating in shallow water.
- Females receptive after laying.
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Sex determination:
Hatching:
- First hours of night when temperature falls below 28º C.
- Hatchlings race into the sea and disappear for several years, returning
to coastal water and benthic feeding when about 20 cm SCL.
Hatchling mortality and predation:
- Eggs heavily predated by ghost crabs and by local carnivores e.g.
mongoose, raccoons, monitor lizards, feral dogs and pigs.
- Hatchlings are eaten by a wide range of predators, especially frigate
birds.
Commensals and disease:
Feeding:
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Algae |
Sponges |
Tunicates |
Coral |
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| Illustrations: M.
Demma © ICRAM |
- Carnivorous: hunts in the crevices in rocks and corals up to depths
of 100m.
- Diet includes corals, tunicates, algae and sponges.
- The species has an extraordinary ability to feed on sponges, remaining
unaffected by sponge toxins and the spicules which embed its gut lining.
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