Dermochelys coriacea
leatherback turtle

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)

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)

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)

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)

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)

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)

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.

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)

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)