Dermochelys coriacea, Leatherback Sea Turtle [+]

Kingdom Animalia Phylum Chordata Class Reptilia Order Testudines Family Dermochelyidae Genus Dermochelys species: Dermochelys coriacea [+ITIS +WoRMS]

← Previous Photo | Next Photo →

Description & Behavior

The leatherback sea turtle, Dermochelys coriacea (Vandelli, 1761), aka leathery turtle, luth and trunkback turtle, is the largest of the sea turtles reaching up to 2.4 m in length and weighing 227-907 kg. Their flippers span an average of 2.7 m from the tip to tip. The "shell" of the leatherback is actually its bones underneath its firm dark brown or black skin which has seven pronounced vertical ridges on its back and five ridges on its ventral side. A tooth-like cusp is located on each side of the upper jaw; the lower jaw is hooked anteriorly.

Sea turtles live in almost every ocean of the world. Their smooth shells and paddlelike flippers help them speed through the water as fast as 24 kph. These long-distance travelers have been known to swim up to 4,828 km.

Although sea turtles cannot withdraw their heads into their shells, the adults are protected from predators by their shells, large size, and thick scaly skin on their heads and necks.

The leatherback can dive to great depths. Turtles equipped with depth recorders dove to over 1,000 m deep. This depth exceeds that reported for any air-breathing vertebrate with the possible exceptions of sperm whales and elephant seals. The shallowest dives occurred at dusk and the deepest at dawn. These leatherbacks were probably feeding on jellyfish that concentrate below 600 m during the day and move into surface waters at dusk. The turtles dove almost continuously with only brief intervals at the surface to breathe.

Sea turtles can rest or sleep underwater for several hours at a time but submergence time is much shorter while diving for food or to escape predators. Breath-holding ability is affected by activity and stress, which is why turtles drown in shrimp trawls and other fishing gear within a relatively short time.

Because sea turtles are difficult to study in the open ocean, scientists are just beginning to learn about the life history of sea turtles. Today, radio transmitters, attached to nesting turtles, help track the sea creatures on their travels and provide valuable information.

World Range & Habitat

The leatherback sea turtle can be found in tropical and temperate seas in the Atlantic, Pacific and Indian Oceans. Its range is as far north as British Columbia, Newfoundland and the British Isles, and as far south as Australia, Cape of Good Hope, and Argentina. The leatherback is the most migratory of all sea turtles.

» GBIF occurrence data in Google Earth [Tips] | Ocean Biogeographic Information System (OBIS) (World Distribution) [about]

Feeding Behavior (Ecology)

The leatherback sea turtle is omnivorous feeding on jellyfish (its primary food source), crabs and fish. They are also known to eat sea urchins, squid, crustaceans, tunicates, blue-green algae and seaweed.

Life History

It is estimated that leatherbacks reach sexual maturity between 6-10 years of age. Although leatherbacks move swiftly in the ocean, they are slow and defenseless on land. Male sea turtles almost never leave the water. Adult females require sandy nesting beaches backed with vegetation and with proximity to deep water and generally rough seas. Like other sea turtle species, leatherback females are fertilized in the sea then leave the water at night to dig their nests where they will deposit between 70-80 eggs. Incubation takes from 55-75 days, and the eggs are hatch at night to avoid predation during the hatchling's return to the sea. It is estimated that 26,000-43,000 females nest annually worldwide—a decline of more than half since 1980. Exponential declines in leatherback nesting have occurred along the Pacific coasts of Mexico and Costa Rica. The leatherback nesting population in Mexico, once the world's largest at 65% of the global nesting population, is now less than 1% of what it was in 1980. The largest nesting populations now occur in the western Atlantic in French Guiana (4,500-7,500/year) and Colombia (3,000/year). The 2nd largest nesting populations are now found in the western Pacific in Indonesia (about 600-650/year). In the United States, small nesting populations occur on the Florida east coast (35 females/year), in the U.S. Virgin Islands (50-100 females/year), and in Puerto Rico (30-90 females/year). In the U.S., nesting occurs from March-July during which time females will nest 5-7 times with an observed maximum of 11 nests. The average internesting interval is about 9-10 days. Most leatherbacks remigrate to their nesting beaches at 2 to 3-year intervals.

Conservation Status/Additional Comments

Unhatched eggs are in high demand driving this species towards extinction. Other factors threatening leatherbacks include coastal development, disorientation of hatchlings by beachfront lighting, egg predation, pollution and watercraft strikes. To prevent extinction of the leatherback, nature reserves have been established in nesting areas and, in some areas, scientists have taken the eggs into captive breeding programs.

Like hawksbills, the meat of the leatherback is one of two turtles that may be toxic to humans and other animals. The flesh is reported to contain chelonitoxin which may cause a number of symptoms including nausea, vomiting, diarrhea, burning sensation of lips, tongue and mouth, chest tightness, difficulty swallowing, hypersalivation, bad breath, skin rash, coma and death.

Leatherback sea turtles, Dermochelys coriacea, are listed as Critically Endangered (CR A1abd) on the IUCN Red List of Threatened Species:

CRITICALLY ENDANGERED (CR)
A taxon is Critically Endangered when it is facing an extremely high risk of extinction in the wild in the immediate future, as defined by any of the criteria (A to E) as described here.

"The main threats have been a prolonged harvest of eggs and the incidental capture in oceanic fisheries. In some areas the egg harvest and illegal poaching has removed more than 95% of the clutches, and this has been recognized as the main cause for the collapse in the Malaysia population (Chan and Liew 1996). Fishing activities using longline and driftnets are an important threat since juvenile and adult are captured in migratory routes (Zug and Parham 1996). In some areas females are killed on the nesting beaches for oil extraction. Leatherback hunts, which have been stripped of their traditional customs and controls, are also serious threats (Suarez and Starbird 1996). Oceanic pollution, basically by plastics is another cause of mortality. Phthalates, derived form plastics have been found in the leatherback egg yolk (Ju�rez-Cer�n 1998)."

"Extraction of sea turtles and their products has become illegal in most countries. In many, there are conservation programmes to protect egg clutches and nesting females from poaching. International trade of all sea turtle products and sub-products is forbidden under CITES. However, the use of the Leatherback meat, oil or eggs is allowed in some nations, as part of internal traditional customs or rituals. While many international instruments (CMS, CBD, SPAW to name a few) require the protection of sea turtles in international waters, lack of effective monitoring in pelagic fishing operations still causes significant bycatch mortality. As an unprecedented action, the United States government recently closed a very large area in the northern Pacific to the US longline fishery in order to protect leatherbacks from incidental capture."

"Because of the decline in the world's populations of the leatherback turtle, full protection of all nesting beaches to eliminate poaching, avoid degradation of critical habitat, and increment hatchling recruitment (through enhancing hatching success and incrementing the number of nesting protection programs) will be necessary. However, as pointed out by Sarti et al. (1996) and Spotila et al. (2000) recovery of this population cannot be achieved by increasing hatchling production alone because of the very high mortalities as fisheries' bycatch. Due to the very drastic observed population declines in last few decades, pelagic and coastal fishing practices that impact leatherbacks must be changed or eliminated urgently to minimize leatherback mortality in these habitats. Further, because the migratory routes of leatherbacks cross territorial waters of many nations or occur in the high seas, international collaboration focused on sea turtle conservation is essential. In regions such as the Caribbean, where populations are shared and the dynamic nature of the nesting habitats provokes shifts in nesting sites, greater collaboration and data sharing will be necessary to derive a better understanding of population sizes and trends."