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Dermochelys coriacea (Vandelli, 1761)Leatherback |
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 Copyright Ginny Bass, 2006 Dermochelys coriacea, laying eggs |
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Dermochelys coriacea
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By Adam Farmer, Annamarie Roszko, Scott Flore, Kevin Hatton, Veronica Combos and Andrea Helton
Leatherbacks are primarily pelagic animals. They travel great distances from their nesting beaches to their feeding grounds. Although leatherbacks are most often found in tropical waters, they are distributed around the globe in temperate oceans, and even on edges of subarctic water. The leatherback sea turtle travels further north than any other sea turtle. They live in Northern Atlantic waters as far north as Newfoundland, Nova Scotia, and Labrador. They also inhabit South Atlantic Waters, as far south as Argentina and South Africa. This turtle inhabits waters as far east as Britain and Norway.
During the nesting season they are discovered along the coasts of French Guiana, Suriname, Guyana, Trinidad, Gabon, West Africa, Parque Marino Las Baulas in Guanacaste, Costa Rica, Papua New Guinea, Andaman and Nicobar Islands, Thailand, in the U.S. on St. Croix, U.S. Virgin Islands, and in Puerto Rico and Florida. The largest nesting colony is in Africa, along the coast of French Guiana. More than 7,000 females laid as many as 50,000 eggs there in 1988 and again in 1992. There is one nesting record in Cape Lookout, North Carolina. ( Eckert, 2006 ; Martof et al., 1980 ; Spotila, 2004 )
Biogeographic Regions:
oceanic islands
(
native
); indian ocean (
native
);
atlantic ocean
(
native
);
pacific ocean
(
native
).
Leatherback sea turtles live in many different oceans throughout the world. They are widely known as pelagic animals but are seen in coastal waters when searching for food. They live in tropical, temperate and even some subarctic oceans. They have been discovered in waters as deep as 1230 m, well below the photic zone.
Leatherbacks lay their eggs in the sand of tropical beaches. It is the only time they emerge onto land, and only the females do so. ( Eckert, 2006 ; Spotila, 2004 )
These animals are found in the following types of habitat:
temperate
;
tropical
;
saltwater or marine
.
Other:
intertidal or littoral
.
The leatherback sea turtle is the largest of living turtles. It may reach a length of ca. 2.13 m. Adults may have a span of ca. 2.7 m from the tip of one front flipper to the tip of the other. They have a secondary palate, formed by vomer and palatine bones. The leatherback has no visible shell. The shell is present but it consists of bones that are buried into its dark brown or black skin. It has seven pronounced ridges in its back and five on the underside. Leatherback hatchlings look mostly black when looking down on them, and their flippers are margined in white. Rows of white scales give hatchling leatherbacks the white striping that runs down the length of their backs.
These turtles feed in waters that are far colder than other sea turtles can tolerate. They have a network of blood vessels that work as a counter-current heat exchanger, a thick insulating layer of oils and fats in their skin, and are able to maintain body temperatures much higher than their surroundings. ( Spotila, 2004 )
Some key physical features:
ectothermic
;
heterothermic
;
bilateral symmetry
.
Sexual dimorphism:
female larger.
Hatching success of clutches is about 50% in an undisturbed nest. Many nests are destroyed by many different predators. Nest temperature determines the hatchlings' sex. At 29.5 degrees Celsius hatchlings are equally likely to be male or female, hatchlings incubated at 28.75°C or less will be male, above 29.75°C they'll be female. Hatchling turtles weigh 35-50 grams, and grow very fast. Leatherbacks may be the fastest growing reptile in the world, reaching adult size in 7 - 13 years. ( Spotila, 2004 )
Special features of growth:
temperature sex determination.
The male leatherback turtles will migrate just offshore a common nesting beach generally before nesting season begins. There they will try and mate with as many females as possible. Also, studies have shown that the males will return to the same nesting beach if they were successful in the previous season. ( Eckert, James, and Myers, 2005 )
Mating systems:
polygynandrous (promiscuous)
.
Leatherback sea turtles mate in the water, just offshore from the females' desired nesting beach. The female then swims ashore at night to nest and will produce a clutch of usually 50 - 170 eggs. However, a large percentage of those eggs are yolkless and will not develop further. The female will lay her eggs and then cover the nest with sand to discourage predation and moderate the temperature and humidity around the eggs. After the female has completed this process she will returns to the ocean. Male leatherback sea turtles never swim to shore and have no part in the nesting process. ( Barbour and Ernst, 1972 ; Beacham, Castronova, and Sessine, 2000 ; Eckert, James, and Myers, 2005 ; Zug and Parham, 1996 )
Key reproductive features:
semelparous
;
seasonal breeding
; gonochoric/gonochoristic/dioecious (sexes separate);
sexual
;
fertilization
;
oviparous
.
The only parental investment that occurs with leatherback sea turtles is when the female lays eggs on the shore and covers her nest after laying the eggs. No subsequent parental care occurs. ( Barbour and Ernst, 1972 )
Parental investment:
pre-fertilization (provisioning, protecting: female).
We have no information on the lifespan of Dermochelys coriacea . ( Barbour and Ernst, 1972 ; Pope, 1939 )
Leatherbacks are mostly solitary. They migrate great distances between nesting and feeding grounds. They seem to locate locations that have high concentrations of jellyfish, and feed near the surface or dive to find the highest concentrations of prey. ( Alderton, 1988 ; Carr, 1952 ; Pope, 1939 )
Key behaviors:
natatorial
;
motile
;
migratory
;
solitary
.
Leatherback turtles are carnivores that feed in the open ocean. Their main prey are gelatinous invertebrates, mainly jellyfish and salps. They are known to eat other kinds of food though, including small crustaceans and fish (possibly symbiotes with jellies), cephalopods, sea urchins, and snails.
Leatherbacks do not have the powerful muscles and hard crushing jaw apparatus that some other sea turtles have for eat hard-shelled prey. Instead they have sharp-edged jaws for biting soft-bodied prey. The esophagus in this species is lined with short spines that point downstream, preventing jellies from escaping once swallowed. ( Caut et al., 2006 ; Houghton et al., 2006 )
Primary Diet:
carnivore
(eats other marine invertebrates).
Animal Foods:
fish; mollusks; aquatic or marine worms; aquatic crustaceans; echinoderms; cnidarians;
zooplankton
.
In modern times, humans have become the primary predator of this species, gathering eggs and killing adults.
Leatherback turtles eggs are consumed by a large variety of predators, including ghost crabs ( Ocypode ), monitor lizards ( Varanus ), wading birds such as turnstones ( Arenaria ), knots ( Calidris ), and plovers Pluvialis ). Many mammals excavate nests as well, including raccoons ( Procyon lotor ) and coatis ( Nasua ), dogs ( Canis ), genets ( Genetta ), mongooses ( Herpestidae ) and pigs ( Suidae ). Most of these same predators will take hatchlings as the little turtles race for the sea, as will raptors ( Falconiformes ), gulls ( Larus ), and frigate birds ( Fregatidae ). In the ocean, small leatherbacks are attacked by cephalopods , requiem sharks ( Carcharhinidae ) and other large fish. Adult leatherbacks are large and powerful enough to have few predators, but jaguars ( Panthera onca ) and other large predators may attack nesting females, and killer whales ( Orcinus orca ) and large sharks may attack them at sea.
Nesting females pack the sand over their clutch of eggs, perhaps to obscure the scent of the eggs and make them harder for small predators to dig up. Hatchlings wait until nightfall to emerge and head for the water, to avoid predators. Throughout their lives leatherbacks are counter-shaded, dark on the dorsal surface and light underneath, to better blend with background light (though the dark dorsal surface is probably also better for basking).
Although they don't have the bony shell of most turtles, they do have a thick layer of connective tissue over bony plates covering much most of their body. Leatherbacks are strong and fast swimmers, and adults may defend themselves aggressively. One adult (c. 1.5 m long) was seen chasing a shark that had apparently attacked it, and once the shark fled, the turtle attacked the boat that the observers were in. ( Caut et al., 2006 ; Chiang, 2003 ; Ernst, Lovich, and Barbour, 1994 )
Leatherback sea turtles are predators that eat mainly jellyfish and other soft-bodied marine animals. Their affect on prey population densities is unknown, but might have been substantial before their populations were reduced by harvesting.
Leatherback eggs and hatchlings may be a significant food source for egg predator populations near their nesting beaches.
Leatherbacks are the host of Conchoderma virgatum , a commensal species of barnacle. ( Eckert and Eckert, 1987 ; Ernst, Lovich, and Barbour, 1994 ; Spotila, 2004 )
This species does not harm humans or cause significant costs. It's flesh is sometimes toxic to humans and other animals, perhaps due to toxins ingested as part of its diet of jellyfish.
Ways that these animals might be a problem for humans:
injures humans (
poisonous
).
Although the flesh of adult leatherbacks can sometimes be toxic, adults and eggs are used for food in some locations, and in a few places the oil from the bodies of adults is extracted for medicinal use and as a waterproofing agent.
Leatherbacks eat jellyfish that are pests for swimmers and fishermen, especially for marine fish-farming. Consumption estimates vary, one study estimated that adult leatherbacks probably eat about 1000 kg of jellyfish per year, an earlier study estimated 2900-3650 kg/yr. ( Ernst, Lovich, and Barbour, 1994 ; Spotila, 2004 ; United States Fish and Wildlife Service, 2007 )
Ways that people benefit from these animals:
food
; body parts are source of valuable material.
IUCN Red List:
[link]
:
Critically Endangered.
US Federal List:
[link]
:
Endangered.
CITES:
[link]
:
Appendix I.
This species is believed to be in serious decline. Populations of nesting females in the Pacific have declined as much as 70-80% in the last decade, and the status of the Atlantic population is unclear. Because females may nest on more than one beach each year, accurate counts are more difficult than for some other turtle species. The species is rated "Critically Endangered" by the IUCN, and "Endangered" by the U.S. Fish & Wildlife Service. It has been listed in Appendix I of the CITES, making any international trade illegal.
The primary threat to the species is commercial fishing: turtles accidentally trapped and drowned in nets and trawls, or hooked or tangled by longlines and trap lines. Harvesting of eggs is a significant problem as well. Also, leatherbacks apparently sometimes eat plastic debris they find in the water, probably mistaking it for jellyfish. This plastic debris is indigestible, and an increasing number of turtles are found dead with blocked digestive tracts.
Nature reserves have been established in the coastal areas where the turtles come to breed to prevent people from stealing the eggs. In some areas, scientists have taken the eggs into captive breeding programs to try to increase the population of the area. Some governments require use of turtle-exclusion devices on fishing gear, but this is not a widespread practice. ( Ernst, Lovich, and Barbour, 1994 ; National Oceanic et al., 2001 )
In July of 2004, the “Marine Turtle Conservation Act” was signed into law in the United States. The purpose of this bill was to aid in the conservation of marine turtles, as well as to assist foreign countries in preserving their nesting habitats. To support this bill there are hopes of creating a “Multinational Species Conservation Fund” to support conservation of imperiled marine turtles, including the leatherback. ( Evans, 2004 )
Find Dermochelys coriacea information at
Adam Farmer (author), Radford University. Annamarie Roszko (author), Radford University. Scott Flore (author), Radford University. Kevin Hatton (author), Radford University. Veronica Combos (author), Radford University. Andrea Helton (author), Radford University. Karen Francl (editor, instructor), Radford University.
Fermin Fontanes (author), University of Michigan.
To cite this page: Farmer, A., A. Roszko, S. Flore, K. Hatton, V. Combos, A. Helton, K. Francl and F. Fontanes. 2007. "Dermochelys coriacea" (On-line), Animal Diversity Web. Accessed February 09, 2010 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Dermochelys_coriacea.html.
Disclaimer: The Animal Diversity Web is an educational resource written largely by and for college students . ADW doesn't cover all species in the world, nor does it include all the latest scientific information about organisms we describe. Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. While ADW staff and contributors provide references to books and websites that we believe are reputable, we cannot necessarily endorse the contents of references beyond our control.
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| Following modified from turtles.org |
The Leatherback Turtle (Dermochelys coriacea)
The following is based on information from the Recovery Plan for U.S. Population of Leatherback Turtles , U.S Fish and Wildlife Service and National Marine Fisheries Service, 1992. Obtained from the U.S. National Marine Fisheries Service, and used with their kind permission. Current StatusThe U.S. Federal government has listed the leatherback as endangered worldwide. Within the U.S., the leatherback is known to nest in Southeastern Florida, Culebra, Puerto Rico, and St. Croix. DescriptionThe leatherback is the largest living turtle and is so distinctive that it is placed in its own separate family, Dermochelys. All other sea turtles have bony hard plates on their shells ( carapace ). The leatherback's carapace is slightly flexible and has a rubbery texture. No sharp angle is formed between the carapace and the under-belly ( plastron ) so a leatherback is somewhat barrel-shaped. Many can grow to be bigger than one too. The front flippers of a leatherback are longer than in the other marine turtles, even when you take the leatherback's size into account. They can reach 270 cm in adult leatherbacks. The largest leatherback on record was a male stranded on the West Coast of Wales in 1988. He weighed 916 kg. Leatherback hatchlings look mostly black when you are glancing down on them, and their flippers are margined in white. Rows of white scales give hatchling leatherbacks the white striping that runs down the length of their backs. While the Recovery Plan (being a scientific document) makes no mention of this, Turtle Trax would be remiss not to mention it here: hatchling leatherbacks are cute and engaging little animals. Of considerable interest is that the core body temperature of adults in cold water has been shown to be several degrees Centigrade above the surrounding water. This allows leatherbacks to prosper in ocean regions where other marine reptiles cannot. Fellow Canadian Michael James of Dalhousie University has been training fishermen in eastern Canada to spot leatherbacks, resulting in numerous sightings and an increased awareness that sea turtles inhabit Canadian waters too. In 1982, Peter Pritchard estimated that 115,000 adult female leatherbacks existed worldwide and that roughly half of them probably were nesting in western Mexico. In recent years, however, the number of nesting leatherbacks has been in an alarming decline. ThreatsLeatherbacks have historically been taken only rarely for their meat. The greatest threat used to be to their eggs, and this threat still exists. There aren't as many eggs to poach these days, however, because fewer and fewer leatherbacks show up to nest. Scientists have concluded that gill-net and longline fisheries are to blame, Commercial FisheriesIn 1987, it was estimated that offshore shrimp fleets capture about 640 leatherbacks each year. About a quarter (160) die from drowning and many others die when they are injured unintentionally on the decks of these trawlers. A few years ago, US regulations made the use of Turtle Excluder Devices (TEDs) mandatory. While compliance remains a problem, TEDs have saved many leatherbacks. A group of sea turtle biologists recently concluded (June, 2000) that gill-net and longline fisheries were probably causing the decline. They published their findings in the prestigious journal Nature . They based their findings on the steep decline in the number of nesting turtles. Although some actions have been taken to limit the impact of longline fishing in the Pacific, the future of the leatherback is still seriously in doubt. Nesting EnvironmentLeatherbacks prefer open access beaches possibly to avoid damage to their soft plastron and flippers. Unfortunately, such open beaches with little shoreline protection are vulnerable to beach erosion triggered by seasonal changes in wind and wave direction. A presumably secure beach can undergo such severe and dramatic erosion that eggs laid on it are lost. The theft of eggs for local consumption is not currently a problem in Florida but continues in low levels in the U.S. Virgin Islands. Even though the harvest of turtle eggs is illegal in Puerto Rico, law enforcement efforts have been unsuccessful in deterring it. Historically, the situation was no better on Puerto Rico's smaller islands: e.g. egg poaching has been described as "extensive and unrelenting" (Carr 1978) and a "major problem" (Tucker 1988) on Culebra. Today poaching has been all but eliminated on Culebra as a result of nightly partrol and nest protection programs initiated by FWS on important nesting beaches in 1984. Leatherbacks are also vulnerable to beach armouring, beach nourishment, artificial lighting, and human encroachment, as described in Threats to Marine Turtles . Entanglement at SeaLeatherbacks are the most pelagic of turtles, feeding in the open ocean rather than near shore as other marine turtles do. At sea, they become entangled fairly often in longlines, buoy anchor lines and other ropes and cables. This can result in injury (rope or cable cuts on shoulders and flippers) or drowning. Ingestion of Marine DebrisLeatherbacks have mistaken plastic bags, raw plastic pellets, plastic and styrofoam, tar balls and balloons for their natural food. Ingesting this debris can obstruct the gut, lead to absorption of toxins and reduce the absorption of nutrients from their real food. Leatherbacks appear to mistake floating plastic in the form of bags or sheets for jellyfish and then eat it. Ten of 33 dead leatherbacks washed ashore between 1979 and 1988 had ingested plastic bags, plastic sheets or monofilament. Conservation AccomplishmentThe Recovery Plan for the U.S. Population of Leatherback Turtles states:
Leatherback Quick FactsReprinted from Florida's Sea Turtles, Copyright 1992, courtesy the Florida Power & Light Company. The leatherback is the largest of the sea turtles; it travels the farthest, dives the deepest and ventures into the coldest water.
Last modified 04/01/24
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