Leatherback Sea Turtle(Dermochelys coriacea)
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General Description:
The leatherback sea turtle ranges from 4- 8 feet and it is considered the largest marine turtle. It weights about 500- 2,000 pounds. The largest leatherback was found stranded on the coast of Wales in 1988 weighing 2,020 pounds [3]. Another interesting fact, a leatherback was recorded to have descended to a maximum depth of 1,280 meters (4,200 feet), which represents the deepest dive ever recorded for a reptile [3]. Leatherbacks must breathe air at the surface, but can stay underwater for up to 35 minutes at a time. The leatherback usually lives around 45- 50 years, but the exact lifespan is unknown since many leatherbacks meet an early end due to human activity. The leatherback's evolutionary roots trace back more than 100 million years. It currently listed as an endangered species [5].


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Special Physical Traits:
The leatherback sea turtle does not have a hard shell, but rather a leathery carapace composed of a mosaic of small bones covered by firm rubbery skin. The carapace is approximately 1.5 inches thick and consists of leathery, oil-saturated connective tissue overlaying loosely interlocking dermal bones [2]. The carapace has seven longitudinal ridges, which make the turtle more hydrodynamic. The leatherback also has unusually long front flippers, which lack claws and scales [2]. The back flippers are paddle-shaped. Both the ridges and long flippers make the leatherback uniquely equipped for their long distance migrations. Leatherbacks lack the chewing plates characteristic of most sea turtles that feed on hard-bodied prey. Instead, the mouth and throat have backward pointing spines that help retain their pray [2].



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Habitat and Feeding:
The leatherback sea turtle is known as pelagic animal, meaning it spends most of its time in the open ocean.Leatherbacks have delicate, scissor-like jaws. Their jaws would be damaged by anything other than a diet of soft-bodied animals. The leatherback's main prey, jellyfish, are found in deeper water [1]. As a major jellyfish predator, the leatherback turtle provides natural control of jellyfish populations. Overabundance of jellyfish may reduce fish populations as jellyfish can feed on fish larvae and reduce population growth of commercially important fish. The presence of leatherback turtles benefits fish, fisheries and people [4]. It is also known to feed on sea urchins, squid, crustaceans, tunicates, fish, blue-green algae, and floating seaweed. The female leatherback does need coastal habitats to lay her eggs. These beaches must be sandy, to allow the turtle to dig an underground nest for her eggs, and must be in close proximity to deep water for once the turtles hatch [1].


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Range:
Leatherbacks are the most widely distributed of all sea turtles. The leatherback sea turtle's unique adaptation system allows them to both generate and retain body heat. These adaptations include large body size, changes in swimming activity and blood flow, and a thick layer of fat [2]. Because of the leatherback's distinct features, they are able to maintain warm body temperatures in colder water. They can be found mainly in tropic and temperate waters of the Atlantic, Pacific and Indian Oceans. Leatherback's migrations average 3,700 miles each way [2].


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Reproduction and Development:
After mating at sea, female leatherback turtles come ashore to nest. The nesting ground must be on a sandy beach and close to deep water. Nests are constructed at night to help keep predators away. Females lay approximately 100 eggs several times, typically at 8-12 day intervals. Eggs usually incubate from 55- 75 days and the emergence of hatchlings occurs at night. The temperature inside the nest determines the sex of the hatchlings [1]. A mix of male and female hatchlings occurs when the nest temperature is approximately 85.1 degrees Fahrenheit, while higher temperatures produce females and cooler temperatures produce males. Female hatchlings that make it to sea will roam the oceans until they reach sexual maturity, when they return to the same nesting areas to produce their own offspring [1]. Males spend the rest of their lives at sea. Most females return to their original nesting spots every 2- 3 years. It is estimated that only 1 in 1,000 survives until adulthood. Leatherbacks are believed to reach sexual maturity in 6- 10 years [1].


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Threats:
Leatherback sea turtles face many threats, most of them imposed by humans. Development of nesting beaches inhibits females from laying their eggs in a desirable location. Irresponsible fishing has also been one of the main causes of the leatherback's decline. Many are caught in fishing lines or struck by boats [3]. Leatherbacks also mistake plastic bags and other types of pollution as jellyfish. Some leatherbacks have been found to have almost 11 pounds (5 kilograms) of plastic in their stomachs [3]. Lastly, the exploitation of nesting turtles and eggs has also greatly affected the leatherback population. After laying the eggs, the female does not stay to protect the nest so it is subject to human and animal predators. Some cultures view the turtle and its eggs as a delicacy, so the people will exploit the nesting grounds [3]. In fact, populations of leatherback sea turtles in the Indopacific crashed by more than 90 percent in the 1980s and 1990s for these exact reasons. Besides human predators, the turtles and eggs also have to endure the natural predators that live near the nesting area [1].


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Conservation Efforts:
There has been a significant amount of conversation efforts to save the leatherback sea turtle. Nesting beaches and near shore habitats are protected by establishing and strengthening sanctuaries and wildlife refuges. Local communities raise awareness to protect turtles and their nests. Various regional agreements are promoted to conserve marine turtles [4]. Through the promotion and facilitation of gear modification there has been a reduction of longline bycatch. Due to the long range migratory movements of sea turtles between nesting beaches and foraging areas, long-term international cooperation is absolutely essential for recovery and stability of nesting populations [4].




Sources:
  1. —"Leatherback Sea Turtle (Dermochelys Coriacea)." North Florida Ecological Services. U.S. Fish and Wildlife Service, 16 Aug. 2011. Web. 01 Oct. 2011. <http://www.fws.gov/northflorida/SeaTurtles/Turtle%20Factsheets/leatherback-sea-turtle.htm>.
  2. —"Leatherback Sea Turtle." Wildlife Conservation Society. Wildlife Conservation Society. Web. 03 Oct. 2011. <http://www.wcs.org/saving-wildlife/ocean-giants/leatherback-sea-turtle.aspx>.
  3. —"Leatherback Sea Turtles, Leatherback Sea Turtle Pictures, Leatherback Sea Turtle Facts - National Geographic." Animals - Animal Pictures - Wild Animal Facts - Nat Geo Wild - National Geographic. National Geographic. Web. 01 Oct. 2011. <http://animals.nationalgeographic.com/animals/reptiles/leatherback-sea-turtle/>.
  4. —"Leatherback Turtle - Underwater Giant on the Brink." World Wildlife Fund. World Wildlife Fund. Web. 01 Oct. 2011. <http://www.worldwildlife.org/species/finder/leatherbackturtle/leatherbackturtle.html>.
  5. —"Leatherback Turtle (Dermochelys Coriacea) - Office of Protected Resources - NOAA Fisheries." NOAA :: National Marine Fisheries Service. NOAA Fisheries, 15 Aug. 2011. Web. 01 Oct. 2011. <http://www.nmfs.noaa.gov/pr/species/turtles/leatherback.htm>.


Multimedia:
Fig G1: http://www.youtube.com/watch?v=qGFhuDUffBI&feature=youtu.be