leatherback turtle (dermochelys coriacea)

8/13/2019 Leatherback Turtle (Dermochelys Coriacea)

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Leatherback turtle (Dermochelys coriacea)

Facts

Kingdom:Animalia

Phylum:Chordata

Class:ReptiliaOrder:Testudines

Family:Dermochelyidae

Genus: Dermochelys

Size:Length: 1.6 m (carapace of average female)

Weight:300 - 600 kg (average female)

Status

Classified as Critically Endangered (CR) on the IUCN Red List 2007. Listed on Appendix I

of CITES and Appendix I of the Convention on Migratory Species (CMS or the Bonn Convention).

Description

The leatherback is the world's largest turtle; the largest recorded individual weighed a

massive 916 kilograms. This turtle earned its common name because it lacks the typical bony plates

on its carapace. Instead, its shell is flexible and covered in a thin layer of leathery skin. This turtle is

dark in colour with white and pink spots. Leatherbacks are easily recognisable by the seven narrow

ridges running the length of the carapace, and by their particularly large front flippers. Females also

have a characteristic 'pink spot' on the top of their heads.

Range

Found throughout the world's oceans with the widest distribution of all the turtles, the

leatherback has been recorded as far north as Alaska and as far south as the tip of South Africa.

These turtles often undertake long-distance migrations, between feeding grounds in temperate

waters and nesting beaches in the tropics, sometimes surpassing 7,000 kilometers over several

months.

HabitatAdults are truly pelagic; they are strong swimmers inhabiting the open seas. Mature females

prefer to nest on sandy tropical beaches with deep-water approaches, although shallow water

beaches are also used in certain regions. Very little is known about juvenile leatherbacks in the

ocean, although recently some small individuals have been found concentrated in waters off western

Africa.

Biology

Adult leatherbacks feed mainly on jellyfish and other soft-bodied species. They are

exceptional amongst reptiles because they are partly able to maintain an elevated body temperaturevia thermal inertia and a specially organized blood supply system in their shoulders. These features


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allow leatherback turtles to travel to cold waters and to dive to depths greater than 1,000 meters in

search of prey.

To nest, females emerge at night on nesting beaches to lay their eggs. Using their rear

flippers they excavate deep 'boot shaped' nests into which roughly 100 eggs are laid. Around 20

percent of the eggs in each nest are small and yolkless. Individuals return to nest every few years,

but within one season a female can lay four to ten clutches of egg . The sex of the hatchlings is

influenced by incubation temperatures: hotter nests produce all females; cooler nests produce allmales.

Normal dietJellyfish and planktonic tunicates. Occasionally fish and other animals associated with

jellyfish.

Normal li festyleThe carapace has the texture of hard rubber, and is raised up into seven longitudinal ridges.

The Leatherback is ecologically unique among sea turtles in its truly pelagic mode of life, althoughsharing with all sea turtles the necessity to nest on land. A powerful swimmer, inhabiting the open

seas, individuals of this species are only rarely sighted away from nesting beaches (with the

exception of those encountered in the few known regularly-frequented feeding areas), and

ecological observations are correspondingly sparse. In at least some parts of the range regular

migrations occur into cool temperate waters to feed on seasonal concentrations of jellyfish. Mean

number of fertile eggs ranges from 66 to 104 on different beaches, typical clutch comprises c 85

eggs. Females may re-nest at 9 to 10 day intervals, four to six times per season. Some females have

been known to re-migrate at 2 or 3 year intervals.

Threats

Several populations of leatherback turtles in the Pacific have plummeted in recent years,

principally due to accidental capture in fisheries and the over-harvest of eggs. Other threats to

leatherbacks worldwide include habitat loss, accidental capture in fisheries, boat strikes, and

ingestion of discarded plastics, which leatherbacks mistake for jellyfish.

Conservation

International trade in leatherback turtles and products is banned under Appendix I of the

Convention on International Trade in Endangered Species (CITES), and the turtle is protectedthroughout most of its range. Many conservation projects have been set up on nesting beaches, with

specific management protocols tailored to each location. The attachment of Turtle Excluding

Devices (TEDs) to shrimp nets can help prevent the accidental capture of turtles and the US

government has recently set up Leatherback Conservation Areas in the north Pacific that are off-

limits to long-line fisheries during certain times of the year. Despite encouraging signs of stable or

increasing populations in the Atlantic, conservationists are concerned that extinction of other

populations is only a matter of time. Recent estimates have suggested there are no more than 2000

breeding females in the eastern Pacific, making this population extremely vulnerable.

The Leatherback is nominally protected by legislation in most countries where nestingoccurs. Listed on CITES (Convention on International Trade in Endangered Species of Wild Fauna

and Flora) Appendix I. Many significant nest beaches are within protected areas. While adults are


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widely protected by law, collection of eggs is permitted or controlled in some areas. In Trengganu

State (Malaysia), for example, a Dermochelys hatchery, now run by the Fisheries Department, was

set up in 1961. Adult Leatherbacks are strictly protected on the nest beach, but virtually all eggs laid

are gathered by licensed egg-collectors. The Fisheries Department buys back a proportion of the

annual egg harvest for transplantation into the hatchery at Rantau Abang. Usually more than 10,000

eggs (sometimes several tens of thousands) are incubated each year, with around 50 per cent

hatching success. The project is currently incubating about 10 per cent of the eggs laid on the beach.Fees paid by egg-collectors for their license contribute towards the cost of running the scheme.

The project may serve to some extent as a model for other areas and species, in that it

combines species conservation through preserving adults and a proportion of the annual egg output,

with local utilisation of eggs as an important and valued food resource. Tourism provides a further

economic benefit. However, it is suspected that the percentage of eggs bought for incubation may

be too small to ensure the continued survival of the population at current levels. It has been pointed

out that killing breeding female Leatherbacks is damaging on both economic and biological

grounds; the adult female is thought to take a long time to mature, but once mature, is potentially

able to lay many eggs. A female only has to nest in two seasons for the monetary value of her eggs

to exceed that of her meat.

Glossary

Bycatch:in the fishing industry, the part of the catch made up of non-target species.

Carapace: the top shell of a turtle. In arthropods (insects, crabs etc), the fused head and

thorax (the part of the body located near the head) also known as cephalothorax.

Pelagic:inhabits the open oceans.

leatherback turtle (dermochelys coriacea)

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