Lepidochelys-olivacea, Olive Ridley, Penyu Ridel, Penyu Lekang

Lepidochelys-olivacea

Olive Ridley, Penyu Ridel, Penyu Lekang

Lepidochelys-olivacea

The OlLepidochelys-olivacea, Olive Ridley, Penyu Ridel, Penyu Lekangive Ridley (Lepidochelys olivacea), also known as the Pacific Ridley, is one of the smallest species of sea turtle. It is named for the olive-green color of its heart-shaped shell.

These lightly-built turtles have an average weight just over 100 lb (up to 50 kg.). They have a high-domed shell, with a carapace length of only 30 inches (70 cm). The carapace is made up of five pairs of coastal scutes, with occurrences of up to 6 to 9 divisions per side. The margins are smooth. The carapace is a dark olive green in color with a yellowish underside. The head is large.

Distribution

It is usually found in the Indo-Pacific and Atlantic oceans. The common name in Spanish is tortuga golfina, del golfo o lora.

The beaches of Orissa, India provide one of the last nesting grounds of the Olive Ridley turtles in the world. In addition, trawling and offshore drilling for oil and gas has been blamed for the death of more than 20 Olive Ridley turtles, which have washed ashore in the last ten years.

Though listed by the US Endangered Species Act, populations in the Atlantic Ocean continue to dwindle, while the populations found in areas around the Pacific Ocean seem to be on the rise. Furthermore, their ability to reproduce in the Red Sea was thought impossible, however, recent evidence suggests that they do indeed hatch in Eritrea amongst other places in the Red Sea.

In Costa Rica is the one of the most ?ortant nesting of this turtle. Ositonal Beach in Guanacaste Province has the mayor concentration of this turtles monthly, where the “arribadas” occur every month. In october and november is when Olive Ridley turtle nest in mayor quantity in this place (aproximately 200 turtles per hour). Nancite Beach and Camaronal Beach in the same province of this Central American country receive a lot of Olive Ridley Turtle, but less than Ostional.

In the Indian Ocean, a major nesting ground for the species can be found in the Indian state of Orissa. Beaches in Devi, Gahirmatha and Rushikulya are known nesting sites for the L. olivacea Indian Ocean population. In 2007, around 130,000 turtles nested on the beaches of Gahirmatha.
Lepidochelys olivacea distribution map. Red circles are major nesting grounds. But the construction of Dhamra Port by TATA Group is supposed to be a major threat to these turtles.Yellow circles are minor nesting beaches.

They are common in the Bay of Bengal, seen especially along parts of the Tamil Nadu coastline, including within the main city, Chennai. Olive Ridleys are seen frequently in laying eggs in the shore of Saint Martin’s Island in Bangladesh.

It is believed that Olive Ridley turtles return to nest on the same beach they are hatched. If this is the case, then on these beaches where efforts are made to protect the eggs and hatchlings there should be rises in the numbers returning to nest in future.

Ecology and life history

Olive Ridleys are omnivorous, feeding on crabs, shrimp, rock lobsters, sea grasses, algae, snails, fish, sessile, pelagic tunocates and small invertebrates. They are sometimes seen feeding on jellyfish in shallow waters. These turtles forage offshore in surface waters and can dive to depths of at least 150 meters (500 feet).

 

Eretmochelys-imbricata, Hawksbill turtle, Penyu sisik

Eretmochelys-imbricata

 Hawksbill turtle, Penyu sisik

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Eretmochelys-imbricata-01-800

ThEretmochelys-imbricata, Hawksbill turtle, Penyu sisik e hawksbill turtle (Eretmochelys imbricata) is a critically endangered sea turtle belonging to the family Cheloniidae. It is the only species in its genus. The species has a worldwide distribution, with Atlantic and Pacific subspecies. Eretmochelys imbricata imbricata is the Atlantic subspecies, while Eretmochelys imbricata bissa is found in the Indo-Pacific region.

The hawksbill’s appearance is similar to that of other marine turtles. It has a generally flattened body shape, a protective carapace, and its flipper-like arms are adapted for swimming in the open ocean. E. imbricata is easily distinguished from other sea turtles by its sharp, curving beak with prominent tomium, and the saw-like appearance of its shell margins. While the turtle lives a part of its life in the open ocean, it is most often encountered in shallow lagoons and coral reefs where it feeds on its chosen prey, sea sponges. Some of the sponges eaten by E. imbricata are known to be highly toxic and lethal when eaten by other organisms. In addition, the sponges that hawksbills eat are usually those with high silica content, making the turtles one of few animals capable of eating siliceous organisms. They also feed on other invertebrates, such as comb jellies and jellyfish.

Because of human fishing practices, Eretmochelys imbricata populations around the world are threatened with extinction and the turtle has been classified as critically endangered by the World Conservation Union.[1] Several countries, such as China and Japan, have valued hunting hawksbill turtles for their flesh, which is considered good eating. Hawksbill turtle shells are the primary source of tortoise shell material, used for decorative purposes. By the Convention on International Trade in Endangered Species, it is illegal to capture and to trade in hawksbill turtles and products derived from them in many nations. Eretmochelys imbricata has the typical appearance of a marine turtle. Like the other members of its family, it has a depressed body form and flipper-like limbs adapted for swimming. Adult hawksbill turtles have been known to grow up to a metre (3.3 feet) in length, weighing around 80 kilograms (176 lbs) on average. The heaviest hawksbill ever captured was measured to be 127 kilograms. The turtle’s shell, or carapace, has an amber background patterned with an irregular combination of light and dark streaks, with predominantly black and mottled brown colors radiating to the sides.The hawksbill turtle has several characteristics that distinguish it from other, closely related species. Its elongated, tapered head ends in a beak-like mouth (from which its common name is derived), its beak more sharply pronounced and hooked than other sea turtles. The hawksbill’s arms have two visible claws on each flipper.

One of the hawksbill’s more-easily distinguished characteristics is the pattern of the thick scutes that make up its carapace. While its carapace has five central scutes and four pairs of lateral scutes like several members of the same family, E. imbricata’s posterior scutes overlap in such a way as to give the rear margin of its carapace a serrated look, similar to the edge of a saw or a steak knife. The turtle’s carapace itself has been known to reach almost a meter in length.

The sand tracks of hawksbill turtles are asymmetrical, as they crawl on land with an alternating gait. This is opposed to the green sea turtle and the leatherback turtle, which crawl rather symmetrically.

Due to its consumption of venomous cnidarians hawksbill turtle flesh can reach certain levels of toxicity.

Distribution

Hawksbill turtles have a wide range, found predominantly in tropical reefs of the Indian, Pacific and Atlantic oceans. Of all the sea turtle species, E. imbricata is the one most associated with tropical waters. Two major subpopulations are acknowledged to exist, the Atlantic and Indo-Pacific subpopulations.
Indo-Pacific subpopulation

The species’ Indo-Pacific population is widespread throughout the entire region. In the Indian Ocean, hawksbills are a common sight all along the east coast of the African continent, including the seas surrounding Madagascar and nearby island groups. The species’ Indian Ocean range stretches all the way along the coast of Asia, including the Persian Gulf and the Red Sea, along the entire coast of the Indian subcontinent, across the entire Indonesian archipelago and the northwestern coast of Australia. The Pacific range of E. imbricata is somewhat limited to the ocean’s tropical and subtropical regions. Its northernmost reach in the region are the waters off the southwestern tip of the Korean peninsula and the Japanese archipelago. The range continues, enveloping the entire region of Southeast Asia, the entire northern coast of Australia all the way south to the northern part of New Zealand. Across the Pacific, hawksbills are known as far north as the Baja peninsula in Mexico, along the waters off the Central American and South American coast to the northern tip of Chile.In the Philippines, there are several known nesting sites for the species. Hawksbill turtle hatchlings have been found on the island of Boracay.A small group of islands in the southwest of the archipelago have been named the “Turtle Islands” precisely because they are known nesting grounds for two species of sea turtle, including Eretmochelys imbricata. (The other being Chelonia mydas, the green turtle.) In Australia, E. imbricata are known to nest on Milman Island in the Great Barrier Reef.In the Indian Ocean, hawksbill turtles have been found to nest as far west as Cousine Island in the Seychelles, where the species has been legally protected since 1994. The Seychelles’ inner islands and islets, such as Aldabra Island, are ripe feeding grounds for immature hawksbills.

Habitat

Adult hawksbill turtles are primarily found in tropical coral reefs. They are usually seen resting in caves and ledges in and around these reefs, throughout the day. As a highly migratory species, they have also been encountered in a wide range of habitats, from the open ocean to lagoons and even mangrove swamps in estuaries. While much is not known about the habitat preferences of early-life stage E. imbricata, like other sea turtles’ young, they are assumed to be completely pelagic and thus make the open sea their home until they mature.

Feeding ecology

While they are known to be omnivorous, the principal food of hawkbill turtles are sponges. Sponges constitute 70 ? 95% of the diets of E. imbricata populations in the Caribbean. However like many spongivores, E. imbricata feed only on a few select species, and will ignore many others. The Caribbean hawksbill populations were found to feed primarily on sponges from the class Demospongiae, specifically ones belonging to the orders Astrophorida, Spirophorida and Hadromerida.Select sponge species known to be fed on by these turtles include Geodia gibberosa. Aside from sponges, hawksbills also feed on algae and cnidarians like jellyfish and sea anemones.The hawksbill is also known to feed on the dangerous jellyfish-like hydrozoan, the Portuguese Man o’ War (Physalia physalis). Hawksbills close their unprotected eyes when they feed on these cnidarians, for Man o’ War’s stinging cells cannot penetrate the turtles’ armoured heads.

Eretmochelys imbricata have shown themselves to be highly resilient and resistant to their prey. Some of the sponges known to be eaten by hawksbills, such as Aaptos aaptos, Chondrilla nucula, Tethya actinia, Spheciospongia vesparium and Suberites domuncula, are highly (often lethally) toxic to other organisms. In addition, hawksbills are known to choose sponge species that have a significant amount of siliceous spicules, such as Ancorina, Geodia, Ecionemia and Placospongia.

Life history
Much is not known about the life history of Eretmochelys imbricata. Hawksbills are known to mate biyearly in secluded lagoons in remote islands throughout their range. Mating season for Atlantic hawksbills usually takes place from April to November. For Indian Ocean populations such as the Seychelles hawksbill population, the mating season is from September to February. As with other sea turtles, hawksbills mate in shallow lagoons off the shores of their prospective nesting beaches. After mating, the females drag their heavy bodies high onto the beach during the night. They will then clear out an area and dig a nesting hole using their rear flippers. The female then lays a clutch of eggs in the nest and then covers them with sand. Caribbean and Florida nests of E. imbricata normally contain around 140 eggs. After the several-hour-long process, the female then returns to the sea. This is the only time when hawksbill turtles are known to leave the ocean.

The baby turtles, usually weighing less than two dozen grams, hatch during the night after around two months. These newly emergent hatchlings are dark-colored, with heart-shaped carapaces measuring around 2.5 centimetres (1 in) long. They instinctually head for the sea, attracted by the reflection of the moon on the water (a mechanism which can be disrupted by anthropogenic light sources such as street lamps and lights). While they emerge under the cover of darkness, baby turtles that do not reach the water by daybreak are preyed upon by predators such as shorebirds and shore crabs.

The early life history of juvenile hawksbill turtles is unknown. Upon reaching the sea, the hatchlings are assumed to enter a pelagic life stage (like other marine turtles) for an undetermined amount of time. While hawksbill turtle growth rates are not known, when E. imbricata juveniles reach around 35 cm, they switch from a pelagic life style to a coral reef-associated one. Hawksbill turtles are hypothesized to reach maturity after thirty years.

While there is no clear consensus because of a lack of data, hawksbill turtles are believed to live from thirty to fifty years in the wild. Like other sea turtles, hawksbill turtles are solitary for most of their lives, they only group together to mate. They were once thought to be habitual, but they are now known to be highly migratory. Because of their tough carapaces, hawksbill turtles have no major predators as there are few creatures that are capable of biting through their protective shell. Sharks and estuarine crocodiles are a few of their natural predators. Octopuses and some species of pelagic fish have also been known to prey on the adult turtles.
Evolutionary history

Within the sea turtles, Eretmochelys imbricata has several unique anatomical and ecological traits, including being the only primarily spongivorous reptile known. Because of this, its evolutionary position has been somewhat unclear. Molecular analyses supports the probability that the Eretmochelydae evolved from carnivorous ancestors rather than herbivorous ones. As the taxonomic tribe Carettini is composed of carnivorous species (such as the loggerhead turtle), the hawksbill most probably evolved from them instead of the herbivorous Chelonini, which includes the green turtle.

Etymology and taxonomic history

The hawksbill turtle was originally described by Carolus Linnaeus as Testudo imbricata in 1766.It was moved into the genus Eretmochelys by the Austrian zoologist Leopold Fitzinger in 1843. In 1857, the species was redescribed as Eretmochelys imbricata squamata, a designation that is now invalid.

There are two accepted subspecies in the E. imbricata taxon. Eretmochelys imbricata bissa (R?, 1835) refers to all known populations of the Eretmochelys imbricata that reside in the Pacific Ocean. The Atlantic population has been found to be a separate subspecies, Eretmochelys imbricata imbricata (Linnaeus, 1766). The subspecies name of imbricata was retained because the type specimen that Linnaeus used to initially describe the species was from the Atlantic.

Fitzinger derived the genus’ name, Eretmochelys from the Greek roots eretmo and chelys, corresponding to “oar” and “turtle” respectively. The name refers to the turtles’ oar-like front flippers. The species’ name imbricata is Latin, corresponding to the English term imbricate. This appropriately describes the turtles’ overlapping posterior scutes. The Pacific hawksbill’s subspecies name, bissa is Latin for “double”. The subspecies was originally described as Caretta bissa and the term referred to the then-species’ being the second species in the genus. Caretta is the genus of the hawksbill’s much larger relative, the loggerhead turtle.

Importance to humans

Throughout the world, hawksbill turtles are taken by humans even though it is illegal to hunt them in many countries. In some parts of the world, hawksbill turtles are taken and eaten as a delicacy. As far back as the fifth century B.C., sea turtles including the hawksbill were eaten as delicacies in China.

Many cultures also use the turtles’ shells for decoration. In China where it was known as tai mei, it is called the tortoise-shell turtle, named primarily for its shell which was used for decoration. In Japan, the turtles are also harvested for their shell scutes, which are called bekko in the local Nihongo. It is used in various personal implements, such as eyeglass frames. In 1994, Japan stopped importing hawksbill shells from other nations. Prior to this, the Japanese hawksbill shell trade was around 30,000 kilograms of raw shells per year. In the west, hawksbill turtle shells have been harvested by the ancient Greeks and ancient Romans for jewelry, such as combs, brushes and rings. A bulk of the world’s hawksbill turtle shell trade is harvested from the Caribbean. In 2006, it was found that processed shells of the turtles are regularly available, often in large amounts in countries in the region, including the Dominican Republic and Colombia.

The hawksbill turtle is depicted on the reverse side of the 20-Venezuelan bol?r and the 2-Brazilian Reais banknotes. A much-beloved fountain sculpture of a boy riding a hawksbill affectionately known as Turtle Boy stands in Worcester, Massachusetts.

[edit] Conservation

General consensus has determined sea turtles, including Eretmochelys imbricata to be at the very least, threatened species because of their long lifespans, slow growth and maturity, and slow reproductive rates. Many adult turtles have been killed by humans both deliberately and incidentally. In addition, the nesting sites of the turtles are also threatened by human and animal encroachment. Small mammals have been known to raid the nesting sites and dig up the turtles’ eggs.[6] In the U.S. Virgin Islands, Eretmochelys imbricata nests (along with the nests of other sea turtles like Dermochelys coriacea) are often raided by mongooses right after being laid.

In 1996, the IUCN Red List of Threatened Species classified Eretmochelys imbricata as critically endangered. Its status as an endangered species was challenged prior to this, with two petitions claiming that the turtle (along with three other species) had several significant stable populations worldwide. These petitions were rejected by the IUCN based on their analysis of data submitted by the Marine Turtle Specialist Group (MTSG). The data given by the MTSG showed that the worldwide population of hawksbill turtles had been reduced by 80% in the last three of the species’ generations, and that was no significant increase in the turtles’ populations as of 1996. In light of this data, the IUCN applied the critically endangered (A1) status upon the species. CR A2 status was denied however, because the IUCN believed that there was insufficient data to show that the population of hawksbill turtles were due to decrease by a further 80% in the future.

Historically, Eretmochelys imbricata was first listed as endangered by the IUCN in 1982.This endangered status continued all the way through several reassessments in 1986, 1988, 1990 and 1994 until it was upgraded in status to critically endangered in 1996 (see above).

The species (along with the entire family Cheloniidae) has been listed on Appendix I of the Convention on International Trade in Endangered Species. It is illegal to import or export turtle products, kill, capture or harass hawksbill turtles.

Local involvement in the conservation efforts for the species have also increased in the past few years. The United States Fish and Wildlife Service has classified the hawksbill turtle as endangered since 1970. The U.S. government has several recovery plans in place for protecting its populations of E. imbricata.

 

Dermochelys-coriacea, Leatherback turtle, Penyu belimbing

Dermochelys-coriacea

 Leatherback turtle, Penyu belimbing

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Dermochelys-coriacea-01-800

ThDermochelys-coriacea, Leatherback turtle, Penyu belimbinge leatherback turtle (Dermochelys coriacea) is the largest of all living sea turtles and the fourth largest modern reptile behind three crocodilians.It is the only living species in the genus Dermochelys. It can easily be differentiated from other modern sea turtles by its lack of a bony shell. Instead, its carapace is covered by skin and oily flesh. Dermochelys coriacea is the only extant member of the family Dermochelyidae. Instead of teeth the Leatherback turtle has points on the tomium of its upper lip. It also has backwards spines in its throat to help it swallow food. Leatherback turtles can dive to depths as great as 4,200 feet (1,280 metres).
Leatherback turtles follow the general sea turtle body plan of having a large, dorsoventrally flattened, round body with two pairs of very large flippers and a short tail. Like other sea turtles, the leatherback’s flattened forelimbs are specially adapted for swimming in the open ocean. Claws are noticeably absent from both pair of flippers. The leatherback’s flippers are the largest in proportion to its body among the extant sea turtles. Leatherback front flippers can grow up to 2.7 meters in large specimens, the largest flippers (even in comparison to its body) of any sea turtle. As the last surviving member of its family, the leatherback turtle has several distinguishing characteristics that differentiate it from other sea turtles. Its most notable feature is that it lacks the bony carapace of the other extant sea turtles. Instead of scutes, the leatherback’s carapace is covered by its thick, leathery skin with embedded minuscule bony plates. Seven distinct ridges arise from the carapace, running from the anterior-to-posterior margin of the turtle’s back. The entire turtle’s dorsal surface is colored dark grey to black with a sporadic scattering of white blotches and spots. In a show of countershading, the turtle’s underside is lightly colored.

Dermochelys coriacea adults average at around one to two meters long and weigh from around 250 to 700 kilograms. The largest ever found however was over three meters from head to tail and weighed 916 kilograms. That particular specimen was found on a beach on the west coast of Wales in the North Atlantic.

Physiology

The metabolic rate of the leatherback is about four times higher than one would expect for a reptile of its size; this, coupled with counter-current heat exchangers, the insulation provided by its oily flesh and large body size, allow it to maintain a body temperature as much as 18°C (32°F) above that of the surrounding water. Its large size also gives the leatherback more capacity to maintain its body temperature than smaller, more ectothermic reptiles.Leatherbacks are also the reptile world’s deepest-divers. Individuals have been discovered to be able to descend deeper than 1,200 meters (3,937 feet).They are also the fastest reptiles on record. The 1992 edition of the Guinness Book of World Records has the leatherback turtle listed as having achieved the speed of 9.8 meters per second (35.28 kilometers / 21.92 miles per hour) in the water.

Distribution

The leatherback turtle is a species with a cosmopolitan global range. Of all the extant sea turtle species, D. coriacea has the widest distribution, reaching as far north as Alaska and Norway and as far south as the Cape of Good Hope in Africa and the southernmost tip of New Zealand. The leatherback is found in all tropical and subtropical oceans, and its range has been known to extend well into the Arctic Circle. Globally, there are three major, genetically-distinct populations. The Atlantic Dermochelys population is separate from the ones in the Eastern and Western Pacific, which are also distinct from each other. A third possible Pacific subpopulation has been proposed, specifically the leatherback turtles nesting in Malaysia. This subpopulation however, has almost been eradicated. The beach of Rantau Abang in Terengganu, Malaysia, had once had the largest nesting population in the world with 10,000 nests per year. However in 2008 only 2 leatherback turtles nested at Rantau Abang and unfortunately the eggs were infertile. The major cause for the decline in the leatherback turtles is the practice of egg collection in Malaysia. While specific nesting beaches have been identified in the region, leatherback populations in the Indian Ocean remain generally unassessed and unevaluated.
 

subpopulation

Leatherback turtles in the Pacific Ocean have been determined to belong to two distinct populations. One population is known to nest on beaches in Papua, Indonesia and the Solomon Islands while their foraging grounds are across the Pacific in the Northern Hemisphere along the coast of Oregon in North America. The Eastern Pacific population forages in the Southern Hemisphere, in waters along the western coast of South America while they nest in beaches on the Pacific side of Central America, specific nesting grounds being in Mexico and Costa Rica. The Malaysian nesting population, reduced to less than a hundred individuals as of 2006, has been proposed as a third major Pacific subpopulation.

There are two major leatherback feeding areas in the continental United States. One well-studied area is just off the northwestern coast of the United States near the mouth of the Columbia River. These waters are excellent feeding grounds for the turtles, where they are believed to be foraging in the nutrient-rich waters of the North Pacific. The other American foraging area for the turtles is located in the state of California.Further north, off the Pacific coast of Canada, leatherbacks have been seen on the beaches of British Columbia.
Indian Ocean subpopulation

While little research has been done on Dermochelys populations in the Indian Ocean, nesting populations are known from Sri Lanka and the Nicobar Islands. It is proposed that these turtles form a separate, genetically distinct Indian Ocean subpopulation.

Habitat

Leatherback turtles can be found primarily in the open ocean. Scientists tracked a leatherback turtle that swam from Indonesia to the U.S. in an epic 20,000-kilometer (13,000-mile) journey over a period of 647 days as it searched for food.The turtles prefer deep water but are most often seen within sight of land. Feeding grounds have been determined to be closer to land, in waters barely offshore. Unusually for a reptile, leatherbacks can survive and actively swim in colder waters; individual turtles have been found in waters as cold as 4.5° Celsius.

The favoured breeding beaches of the leatherback turtle are mainland sites facing deep water and they seem to avoid those sites protected by coral reefs.

Trophic ecology

Adult Dermochelys coriacea subsist on a diet almost entirely composed of jellyfish. Due to its obligate feeding nature, it has been hypothesized that leatherback turtles play a role in the control of jellyfish populations.Leatherbacks are also known to feed on other soft-bodied marine organisms such as tunicates and cephalopods.

Dead leatherbacks that wash ashore have been studied to be veritable microecosystems on their own while in the process of decomposition. A drowned leatherback carcass observed in 1996 was observed to have been host to sarcophagid and calliphorid flies after being picked open by a pair of Coragyps atratus vultures. Infestation by known carrion-eating beetles of the Scarabaeidae, Carabidae, and Tenebrionidae families soon followed suit. After days of decomposition, beetles from the families Histeridae and Staphylinidae and anthomyiid flies invaded the corpse as well. All in all, organisms from more than a dozen families took part in decomposition of the leatherback carcass.

Life history

Like all sea turtles, leatherback turtles start their lives as hatchlings bursting out from the sands of their nesting beaches. Right after they hatch, the baby turtles are already in danger of predation. Many are eaten by birds, crustaceans, other reptiles, and also people before they reach the water. Once they reach the ocean they are generally not seen again until maturity. Very few turtles survive this period to become adults. It is known that juvenile Dermochelys spend a majority of their particular life stage in more tropical waters than the adults. Adult Dermochelys are prone to long-distance bouts of migration. Migration in leatherback turtles occurs between the cold waters in which mature leatherbacks cruise in to feed on the abundant masses of jellyfish that occur in those waters, to the tropical and subtropical beaches in the regions where they were hatched from. In the Atlantic, individual females tagged in French Guiana off the coast of South America have been recaptured on the other side of the ocean in Morocco and Spain.

Mating takes place at sea. Leatherback males never leave the water once they enter it unlike females which crawl onto land to nest. After encountering a female (who possibly exudes a pheromone to signal her reproductive status) a leatherback male uses head movements, nuzzling, biting, or flipper movements to determine her receptiveness. Females are known to mate every two to three years. However, leatherbacks have been found to be capable of breeding and nesting annually. Fertilization is internal, and multiple males usually mate with a single female. However, studies have shown that this process of polyandry in sea turtles does not provide the offspring with any special advantages.

While the other species of sea turtles almost-always return to the same beaches they hatched from, female leatherback turtles have been found to be capable of switching to another beach within the same general region of their “home” beach. Chosen nesting beaches are made of soft sand since their shells and plastrons are softer and easily damaged by hard rocks. Nesting beaches also have shallower approach angles from the sea. This is a source of vulnerability for the turtles because such beaches are easily eroded. Females excavate a nest above the high-tide line with their flippers. One female may lay as many as nine clutches in one breeding season. About nine days pass between nesting events. The average clutch size of this particular species is around 110 eggs per nest, 85% of which are viable. The female carefully back-fills the nest after, disguising it from predators with a scattering of sand.

Cleavage of the cell begins within hours of fertilization, but development is suspended during the gastrulation period of movements and infoldings of embryonic cells, while the eggs are being laid. Development soon resumes, but the embryos remain extremely susceptible to movement-induced mortality in their nests until the membranes fully develop through the first 20 to 25 days of incubation, when the structural differentiation of body and organs (organogenesis) soon follows. The eggs hatch in about sixty to seventy days. As with other reptiles, the ambient temperature of the nest determines the sex of the hatchlings. After nightfall, the hatchlings dig their way to the surface and make their way to the sea.

As a global species with a range spanning both hemispheres, leatherback nesting seasons vary from place-to-place. Nesting occurs in February to July in Parismina, Costa Rica. Farther east in French Guiana, Dermochelys populations nest from March to August.Atlantic leatherback turtles nest between February and July from South Carolina in the United States to the United States Virgin Islands in the Caribbean and to Suriname and Guyana.[citation needed] With nearly 30,000 turtles visiting its beaches each year to April, Mayumba National Park is the most important leatherback turtle nesting beach in Africa, and possibly worldwide.

Evolutionary history

Leatherback turtles have been around in some form since the first true sea turtles evolved over 110 million years ago during the Cretaceous. The dermochelyids, as represented by the single living species D. coriacea, are close relatives of the family Cheloniidae which contain the other species of extant sea turtles. However, phylogenetic analysis has determined their sister taxon to be the extinct family Protostegidae which also included species with no hard carapace.

Etymology and taxonomic history

Dermochelys coriacea is the only species in its genus Dermochelys. The genus in turn, contains the only extant members of the leatherback turtle family Dermochelyidae.

The species was first described in 1761 by Domenico Vandelli as Testudo coriacea. In 1816, the genus Dermochelys was coined by the French zoologist Henri Blainville. The leatherback was then reclassified under this own genus as Dermochelys coriacea.Later on, the species was classified in its own family of Dermochelyidae in 1843 by the zoologist Leopold Fitzinger. In 1884, the American naturalist Samuel Garman described members of the species as Sphargis coriacea schlegelii. The two described leatherback species were then united in D. coriacea with each given subspecies status as D. coriacea coriacea and D. coriacea schlegelii. The two subspecies were later rendered invalid synonyms of the species Dermochelys coriacea.

The turtle’s common name comes from the leathery texture and appearance of its carapace. Aside from “leatherback” turtle, it has been called the “leathery turtle” in the past. The turtle was also once referred to as the “trunk” turtle, though the name is now in disuse.

Importance to humans

The harvesting of sea turtle eggs is still practiced by people around the world. Asian exploitation of the turtle’s nests have been cited as the most significant factor for the species’ global population decline. In Southeast Asia, the collection of leatherback eggs has led to a near-total collapse of local nesting populations in specific countries like Thailand and Malaysia. Specifically in Malaysia, where the turtle is practically locally extinct, the eggs are considered a delicacy. In the Caribbean, some cultures consider the eggs of sea turtles to be aphrodisiacs.

Conservation

Adult leatherback turtles are large animals that have few natural predators. The most vulnerable stages in a leatherback’s life are their early life stages at which point they are most vulnerable to predation of all kinds. Birds, small mammals, and other opportunists are known to dig up nests and consume eggs. New hatchlings are also vulnerable on their journey from nest to sea. Shorebirds and crustaceans are known to prey on the turtles scrambling for the sea. Once they enter the water they become prey to a whole new host of predators such as predatory fish and cephalopods. Very few survive to adulthood.

Leatherback turtles have slightly fewer human-related threats than the other sea turtle species. As their flesh contains higher oil and fat content than other species’, there is not much demand for their flesh. However, human activity still significantly endangers leatherback turtles in direct and indirect ways. Directly, a small amount of leatherback turtles are caught for their meat by subsistence fisheries. Nests are raided for eggs by humans in a few places around the world, such as Southeast Asia. Aside from targeted efforts at catching adults and collecting their eggs, there are many human activities that indirectly harm Dermochelys populations worldwide. As a pelagic species, D. coriacea individuals are occasionally caught as bycatch by commercial fishing vessels. As they are the largest sea turtles alive today, turtle excluder devices can be ineffective with adult leatherbacks of a particular size range. It is reported that an average of 1,500 mature females were accidentally caught annually in the 1990s. Pollution, both chemical and physical, can also be fatal to leatherback turtles. With their main diet consisting of jellyfish, many turtles die from malabsorption and intestinal blockage following the ingestion of balloons and plastic bags which resemble their prey.[5] Chemical pollution has also had an adverse effect of the Dermochelys population. A high level of phthalates has been measured in the yolk of D. coriacea eggs.

Global conservation initiatives

It is also listed on Appendix 1 of the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES). This makes it illegal to harm or kill the turtles.

Conservation of the Pacific and Eastern Atlantic leatherback populations was included among the top ten issues in turtle conservation in the first State of the World’s Sea Turtles report published in 2006. Specifically noted were the significant population declines in the Mexican, Costa Rican and Malaysian populations. The Eastern Atlantic nesting population was noted for being threatened by increased fishing pressures from Eastern South American countries in whose waters the leatherbacks forage.

The Leatherback Trust is an organization that was founded specifically towards the aim of the conservation of all marine turtles, specifically their namesake. The foundation was responsible for the establishment of a sanctuary in Costa Rica, the Parque Marino Las Baulas.

Country-specific conservation initiatives

As a species with a range encompassing dozens of coastal countries around the world, the leatherback turtle has been subject to differing country-specific laws regarding its conservation.

The United States has listed the leatherback turtle as an endangered species since June 2, 1970. The protected status of the species (in United States waters) was ratified with the passing of the U.S. Endangered Species Act three years after. Farther north in Canada, where the leatherback turtle can also be found, the Species Risk Act was established to make it illegal to exploit the species in Canadian waters. It has been classified endangered by the Committee on the Status of Endangered Wildlife in Canada. Ireland and Wales have initiated a joint leatherback conservation effort between the University of Wales Swansea and University College Cork. Funded by the European Regional Development Fund, the Irish Sea Leatherback Turtle Project as the project is called, focuses on serious research programs such as tagging and satellite tracking of individual leatherback turtles.

Several Caribbean countries have started conservation programs focused on using ecotourism to bring attention to the plight of the leatherback. On the Atlantic coast of Costa Rica, the village of Parismina has one such initiative. Since 1998, the village has been assisting turtles with a hatchery program.[43] Mayumba National Park in Gabon, Central Africa was created to protect the most important leatherback turtle nesting beach in Africa. More than 30,000 turtles come to nest on Mayumba’s beaches between September and April each year.

A more drastic measure that is being studied by the Malaysian Fisheries Department is cloning. In mid-2007, the Fisheries Department expressed a plan to clone leatherback turtles to replenish the country’s rapidly-declining Dermochelys population. Some conservation biologists however, are skeptical of the proposed plan as cloning has been done only on mammals such as dogs, sheep, cats, and cows, and uncertainties persist about cloned animals’ health and life spans. Leatherbacks used to nest in the thousands on many of Malaysia’s beaches, including those at Terengganu where more than 3,000 nesting females were counted in the late 1960s. The last official count of nesting leatherback females on that beach was recorded to be a mere two females in 1993.

In Brazil, reproduction of the leatherback turtle is being assisted by the IBAMA’s “projeto TAMAR” (TAMAR project), which aims to protect all sea turtles in the Brazilian coast, by assisting their nests and preventing accidental kills by fishing boats. The last official count of nesting leatherback females in Brazil was recorded to be only seven females.

It is listed as Vulnerable under Australia’s Environment Protection and Biodiversity Conservation Act 1999, and as Endangered under Queensland’s Nature Conservation Act 1992.

 

Chelonia-mydas,  Green turtle, Penyu Hijau

Chelonia-mydas

Green turtle, Penyu Hijau

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Chelonia mydas, commonly known as the green turtle is a large sea turtle belonging to the family Cheloniidae. It is the only species in the genus Chelonia. The range of the species extends throughout tropical and subtropical seas around the world, with two distinct populations in the Atlantic and Pacific Oceans. Their common name derives from the green fat underneath their shell.

The green turtle is the quintessential sea turtle, possessing a dorsoventrally-flattened body covered by a large, teardrop-shaped carapace and a pair of large, paddle-like flippers. It is lightly-colored all around, while its carapace’s hues range from olive-brown to black in Eastern Pacific green turtles. Unlike other members of its family such as the hawksbill and loggerhead turtles, Chelonia mydas is mostly herbivorous. The adults are commonly found in shallow lagoons, feeding mostly on various species of seagrass.

Like other sea turtles, green turtles are known to migrate long distances between their feeding grounds and the beaches they hatched from. Many islands worldwide have been called Turtle Islands primarily for the large amounts of green turtles that nest on their beaches each year. Female turtles dredge themselves onto beaches and lay eggs in nests that they dig during the night. After a period of time, hatchlings emerge from the nests and head for the water. Those that survive grow to maturity and live to a maximum of eighty years.

As a species recognized as endangered by the IUCN and CITES, Chelonia mydas is protected from exploitation in most countries worldwide. It is illegal to collect, harm or kill individual turtles. In addition, many countries have implemented various laws and ordinances to protect individual turtles and turtle nesting areas within their jurisdiction. However, the turtles’ populations are still in danger because of several human practices. In some countries, the turtles are still hunted for their flesh and their eggs are collected from nests and eaten as a delicacy. Pollution indirectly harms the turtle populations both on the population and the individual scale. Many turtles die as a result of being caught in fishermen’s nets and drowning. Finally, habitat loss due to human development is a major reason for the loss of green turtle nesting beaches.

The range of Chelonia mydas extends throughout tropical and subtropical oceans worldwide. There are two major subpopulations of C. mydas, the Atlantic and the Eastern Pacific subpopulations. Each population is genetically-distinct, with has its own set of nesting and feeding grounds within the population’s known range
In the Pacific, the range of the green turtle reaches as far north as the southern coast of Alaska and as far south as Chile in the east. The turtle’s distribution in the Western Pacific is known as far north as Japan and even southern parts of Russia’s Pacific coast and as far south as the northern tip of New Zealand and a few islands further south of Tasmania. The turtles can be found throughout the entire range of the Indian Ocean.

Significant nesting grounds are scattered throughout the entire region. Pacific green turtle nesting grounds are found in Mexico, the Hawaiian Islands including O’ahu’s Turtle Bay, the South Pacific, the northern coast of Australia and Southeast Asia. In the Indian Ocean, major nesting colonies have been recorded in India, Pakistan and other coastal countries in the region. A few nesting grounds have been reported along the east coast of the African continent including some islands in the waters around Madagascar.
East Pacific green turtles nesting grounds are well-studied all along the Mexican coast. These turtles have been found to feed in seagrass pastures in the Gulf of California. Green turtles belonging to the distinct Hawaiian subpopulation are known to nest at the protected French Frigate Shoals some 800 kilometers to the west of the Hawaiian Islands.In the Philippines, green turtles are known to nest in the Turtle Islands along with closely-related hawksbill turtles. There are also a few nesting beaches in Indonesia, one of them in the Meru Betiri National Reserve in East Java. The green sea turtles on the Great Barrier Reef have two genetically distinct populations; one in the Northern Great Barrier Reef, and the other in the Southern half of the reef. Within the reef, twenty separate locations consisting of small islands and cays were identified as nesting sites for either population of C. mydas. Of these, the most important green turtle nesting ground was identified to be on Raine Island.

Major nesting sites of green turtle are common on either side of the Arabian Sea, both in Ash Sharqiyah, Oman, and along the coast of Karachi, Pakistan. Some specific beaches along the area, such as Hawke’s Bay and Sandspit, are the common nesting grounds for the region’s C. mydas and L. olivacea subpopulation. Sandy beaches along Sindh and Balochistan are also known green turtle nest sites. Some 25 kilometers off the Pakistani coast, Astola island is another known nesting beach.

On December 30, 2007, fishermen, using a “hulbot-hulbot” or a fishnet accidentally caught an 80-kilogram, 93 centimeters in length and 82 cm wide, green sea turtle off Barangay Bolong, Zamboanga City, Philippines. December is breeding season of the green sea turtles near the Bolong beach.

Ecology and life history

As one of the oldest sea turtle species studied, much of what is known of sea turtle ecology was gleaned from studies of green turtles. The ecology of Chelonia mydas changes drastically with each succeeding stage of its life history. For instance, newly-emerged hatchlings are carnivorous, pelagic organisms part of the open ocean mini-nekton. In contrast, immature juveniles and adult turtles are commonly found in seagrass meadows closer inshore as herbivorous grazers.

Habitat

Green turtles alternate between three habitat types depending on their current life history stage. Nesting beaches are where the turtles return to lay eggs. Mature turtles spend most of their time in coastal, shallow waters with lush seagrass beds. Seagrass meadows within inshore bays, lagoons and shoals are common locations where adult Chelonia mydas can often be found. This particular species is known to be very selective about their feeding and mating sites and entire generations will often alternately migrate between the same feeding and nesting areas.

After hatching, turtles in their first five years are known to spend a majority of their early life stages in convergence zones within the open ocean.[2][27] These young turtles are rarely seen as they swim in deep, pelagic waters where they spend the first few years of their lives.[28][29]

Trophic ecology

As large and well-protected animals, adult green turtles have few enemies and even fewer predators. Only human beings and the larger sharks are known to feed on C. mydas adults. Specifically, tiger sharks (Galeocerdo cuvier) are known predators of adult green turtles in Hawaiian waters.Juvenile turtles and recently-emerged hatchlings have significantly more predators, including crabs, small mammals and shorebirds.

Adult Chelonia mydas are obligately herbivorous. They almost-exclusively feed on various species of seagrasses and seaweed.They have been observed grazing on various species of macroalgae, specifically Caulerpa, Turbinaria, Spyridia, Codium, and Ulva.While mature green turtles are entirely herbivorous, juveniles are known to subsist on a plethora of marine invertebrates. Select preferred prey items include smaller cnidarians and crustaceans. Their digestive intake of plant matter grows larger as they age, until as mature adults they become obligate herbivores.While it has been previously stated that green turtles do not feed while at their respective nesting areas, it has been shown that gravid turtles do in fact feed while in the waters surrounding their nesting grounds.

Life history
Unlike most sea turtles, which spend most of their adult lives in the ocean, Pacific green turtles are known to willingly crawl onto secluded beaches during the day to bask in the sun.

Green turtles migrate long distances between their chosen feeding sites and the beaches from where they hatched. Some C. mydas are known to swim distances of greater than 2,600 kilometers (1,400 nmi) to reach their spawning grounds. Mature turtles will often return to the same exact beach from which they hatched. Individual female green turtles usually mate every two to four years. Males on the other hand, are known to make the trip to their breeding areas every year. As with many species that are found across a wide range of latitudes, mating seasons vary between populations. For most Chelonia mydas in the Caribbean, mating season is from June to September. The French Guiana nesting subpopulation nests from March to June. In the tropics, green turtles are known to nest throughout the year, with some subpopulations preferring particular times of the year. In Pakistan, Indian Ocean C. mydas nest all year-round but prefer to nest during the months of July to December.

Green turtles reproduce in the typical way that marine turtles do so. Female turtles control mating; males cannot force females to mate. While it does not seem to offer increased survival among the hatchlings, a few green turtle populations are known to undergo polyandry when mating.[33] After mating in the water, the females haul themselves onto the beach above the high tide line. Upon reaching a suitable nesting site, the gravid female then digs a hole with her hind flippers and deposits a number of eggs in the nest. The number of eggs laid per litter depends on the age of the female and differs from species to species, but C. mydas clutches range between 100 to 200 eggs. After laying eggs, the female then covers the nest with sand and returns to the sea.
After around 45 to 75 days, the eggs hatch. As with other marine turtles, C. mydas eggs hatch during the night and the newly-emerged turtles instinctively head directly towards the water’s edge. This undoubtedly is the most dangerous time in a turtle’s life, as the hatchlings make their way to the water, various predators such as gulls and crabs pick off many turtles. A significant percentage of turtle hatchlings never make it to the ocean. Just like other sea turtles, little is known of the early life history of newly-hatched green turtles. After this trek to the ocean juvenile green turtles spend from three to five years in the opean ocean as carnivores before they settle as immature juveniles into a more herbivorous, shallow-water lifestyle. It is speculated that they take twenty to fifty years to reach mature size. Individuals of the species are known to live up to eighty years in the wild.

One of the most significant mass-nesting sites for this species is located on Ascension Island in the South Atlantic. Each year on the island, thousands of C. mydas create between 6,000 and 15,000 nests. These particular turtles are among the largest green turtles in the world, many more than a meter in length and weighing up to 300 kilograms.

Evolutionary history

The green turtle is a member of the tribe Chelonini. In a study conducted in 1993, the status of the genus Chelonia with respect to the other marine turtles was clarified. The carnivorous Eretmochelys (hawksbill), Caretta (loggerhead) and Lepidochelys (Ridley) were confirmed in the tribe Carettini. Herbivorous Chelonia were found distinct enough to warrant their status while establishing that Natator (flatback) was further-removed than previously believed.

Etymology and taxonomic history

The species was originally described by Linnaeus in 1758 as Testudo mydas. In 1868, Bocourt described a particular species of sea turtle as Chelonia agassizii (Chelonia agassizi is a commonly-cited misspelling of this taxon).This “species” was referred to as the black sea turtle. However, research determined that the “black sea turtle” was not genetically distinct from C. mydas and thus taxonomically not a separate species.These two separate species were then united in the same species, Chelonia mydas and were given subspecies status. C. mydas mydas referred to the originally described population while C. mydas agassizi referred to the Pacific population.This subdivision was later determined to be invalid and all members of the species were then designated Chelonia mydas.The oft-mentioned name C. agassizi remains an invalid junior synonym of C. mydas.

The species’ common name is derived not from any particular green external coloration of the turtle. The green turtle is so-called because of the greenish color of the turtle’s fat, which is only found in a layer between their inner organs and their shell. As a species found worldwide, the green turtle is called differently in some languages and dialects. In Hawaii, the Hawaiian language word honu is used to refer to this species.

Importance to humans

While in most countries it is now illegal to hunt Chelonia mydas along with the other members of its family, sea turtles continue to be caught worldwide. Along with other sea turtles, Chelonia mydas are caught both intentionally and unintentionally in select regions of the world. Prior to the implementation of various protection measures, the turtles’ skin was tanned and used as leather for handbags, especially in Hawaii.In ancient China, the flesh of sea turtles including and especially C. mydas was considered a culinary delicacy. Particularly for this species, the turtle’s calipee, fat and cartilage are sought as ingredients for making turtle soup.

In some countries like India and China it is considered as a sacred animal according to vastu, astrology and feng shui. Putting turtles into aquariums or in one’s house is considered to ensure the family’s life to be long and it eliminates all negative energies of the house.

In Indonesia, sea turtle eggs are a popular delicacy in Java. However, the turtle’s flesh is regarded as ḥarām or “unclean” under Islamic law (Islam is the primary religion in the region). In Bali, the demand for turtle meat to satisfy traditional consumption at ceremonial and religious feasts has encouraged the harvesting of turtles in the furthest and remotest parts of the Indonesian archipelago. Bali has been importing sea turtles since the 1950s as its own turtle supplies were said to be severely depleted.The ethnic Balinese do not eat the eggs, which are instead sold to local Muslims. The former traditional uses of turtle on Bali were once deemed sustainable, but have been questioned considering a vastly larger human population and thus greater demand. The harvest was until recently described to be the most intensive in the world.

Before the inclusion of the turtles in the Endangered Species Act and the Convention on International Trade in Endangered Species, commercial farms such as the Cayman Turtle Farm in the West Indies bred the turtles for commercial sale. The farms held as many as 100,000 turtles at any one time. When the markets were closed due to protection measures, some farms went bankrupt and most drastically reduced their stock. The farms have since been converted into tourist attractions with around 11,000 turtles at any one time.

Conservation
There are various threats to the species’ survival. Direct and directed threats to individual turtles include hunting of turtles for their flesh and shells and the harvesting of their eggs. More prevalent indirect threats include casualties due to turtles being injured by boat propellers, being caught as bycatch by fishermen’s nets without TEDs, pollution and habitat destruction. Pollution effects would include direct-impact disturbances such as effluent from harbors near nesting sites. Habitat loss usually occurs due to human development of their nesting areas. Urban development of beaches, reclamation and an increased level of tourism are examples of such development. An infectious tumor-causing disease known as fibropapillomatosis is also a problem in some green turtle populations. The disease kills a sizeable fraction of the turtles that it infects, though some turtles seem to be resistant to the disease.

Because of these, the many populations of Chelonia mydas worldwide are in various states of vulnerability. The Mediterranean green turtle population is particularly listed as critically endangered.In the East Pacific, green turtle subpopulations in Hawaii and Southern California have been designated threatened. Specific Mexican subpopulations are listed as endangered. In the Caribbean, the Florida nesting population is also listed as endangered. In the Indian Ocean, the World Wide Fund for Nature has labeled nesting populations in Pakistan as “rare and declining.”

Global conservation initiatives

Since 2004, Chelonia mydas has been classified by the IUCN Red List of Threatened Species as endangered. It is listed as classified under the EN A2bd criteria, which essentially states that the species’ wild populations are facing a high risk of extinction because of several factors. These factors include a probably reduction of more than 50% in the size of the worldwide C. mydas population over the past decade. This was determined by using abundance indices and by projecting a potential level of exploitation of the species’ numbers.
The species has been officially classified as an endangered species since 1982, when the International Union for the Conservation of Nature listed Chelonia mydas as endangered. Throughout various reassessments and subsequent publications, the conservation status of the turtle has not changed over time. The 1986, 1988, 1990 and 1994 editions of the IUCN Red List retained the species’ endangered status. In the landmark 1996 edition of the Red List, C. mydas remained listed as an endangered species.In 2001, a petition was filed to delist the species as an endangered species. At the time, the species was listed as endangered under the strict EN A1abd criteria. The petitioner claimed that at the time, there was ample evidence to suggest that some green turtle populations were large, stable and in some cases, increasing. The IUCN Standards and Petitions Subcommittee determined in a ruling that visual counts of nesting females could not be considered as “direct observation” and thus downgraded the species’ status as EN A1bd – retaining the turtle’s endangered status.

As a member of the family Cheloniidae, Chelonia mydas is listed on Appendix I of the Convention on International Trade in Endangered Species as of May 3, 2007.[56] The species was originally listed on Appendix II in 1975. The entire family was put onto Appendix I in 1977, with the exception of the Australian population of C. mydas. In 1981, all populations of the species were brought into Appendix I, including the Australian population. As covered by Appendix I of CITES, it is illegal to import or export, kill, capture or harass green turtles.

Country-specific conservation initiatives
In addition to management by global entities such as the IUCN and CITES, specific countries around the world whose jurisdiction turtle nesting and feeding grounds fall under have taken specific conservation efforts in order to protect the species.

Eco-tourism has been one specific thrust in Sabah, Malaysia. The island of Pulau Selingan is home to a turtle hatchery. Staff on the island collect some of the eggs laid each night and place them in a hatchery to protect them from predators. Incubation of the eggs apparently takes around sixty days. Once hatched, tourists are permitted to assist in the release of the baby turtles into the sea.In the United States, the U.S. Fish and Wildlife Services classified Chelonia mydas as a threatened species, rendering it a federal offense to capture or otherwise kill an individual turtle. In part due to this, the Hawaiian green turtle subpopulation has made a remarkable comeback and is now also the subject of eco-tourism and has become something of a state mascot. Students of Hawaii Preparatory Academy on the Big Island have tagged thousands of specimens since the early 1990s. In the United Kingdom the species is protected by a Biodiversity Action Plan, due to harvesting in excess from human overpopulation and marine pollution. The Pakistani-branch of the World Wide Fund for Nature has been initiating various projects for secure turtle hatching since the 1980s. However, the population has continued to decline due to various factors

In the Atlantic, conservation initiatives have centered around nesting sites in the Caribbean. The Tortuguero nesting beaches in Costa Rica have been the subject of egg-collection limits since the 1950s. Two decades after, the Tortuguero National Park formally established in 1976 ensuring the protection of that region’s nesting grounds.On Ascension Island where some of the species’ most important nesting beaches are, an active conservation program has been implemented.. Karumb?as been monitoring foraging and developmental areas of juvenile green turtles Chelonia mydas in Uruguay from 1999.

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Caretta-caretta, Loggerhead Sea Turtle

Caretta-caretta

Loggerhead Sea Turtle

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ThCaretta-caretta, Loggerhead Sea Turtlee Loggerhead Sea Turtle (Caretta caretta) is a sea turtle and the only member of the genus Caretta. The genus name “Caretta” is a latinization of the French “caret”, meaning turtle, tortoise, or sea turtle. A loggerhead sea turtle reportedly grows up to 800 lbs (364 kg) and 3.5 feet (1.1 m) long.Their shell color is a reddish brown color, and the color of their skin is brown yellow. They are named for their disproportionately large head. They are also the state reptile of South Carolina.

The species feeds on molluscs, crustaceans, fish, jellyfish, crabs, shrimp and Portuguese Man o’ War and other small to medium-sized marine animals, which they crush with their large and powerful jaws. As with other sea turtles, females return to lay their eggs on or near the same beach where they hatched. Unlike other sea turtles, courtship and mating usually do not take place near the nesting beach but rather along the migration routes between feeding and breeding grounds.

Scientists in Hawaii use satellite transponders to track loggerhead sea turtles in the Northern Pacific Ocean..

Life history

In the Mediterranean, Loggerheads mate from late March to early June. The female nesting season is at its peak in June and July, but this depends on the nesting beach. The clutch may vary from 70 to 150 eggs. Each egg is roughly the size and shape of a ping-pong ball. The average interval between nesting seasons is two to three years.

Loggerhead turtles are the most common sea turtle to nest in the United States. Loggerheads nest from Texas to Virginia to North Carolina, requiring soft sandy beaches, where there is little light pollution; with the largest concentration of nests in south Florida. Statistics collected in Florida since 1998 however indicate the lowest nesting levels Florida has seen in 17 years, where nesting rates have declined from 85,988 nests in 1998 to approximately 45,084 in 2007.

After approximately 60 days, the hatchlings emerge usually at night when protection from predation is greater. Because they usually follow the brightest light to the ocean’s edge, artificial lights from human activity can lead them astray. Once in the ocean they use ocean currents to travel to the Sargasso Sea using the Sargassum as protection until they mature.

An alternative to migration for many loggerheads is hibernation to varying degrees as the water cools. Loggerhead turtles have no bones on the tip of their front legs. By February they are submerged for up to seven hours at a time, emerging for only seven minutes to recover. Although outdone by freshwater turtles, these are the longest recorded dives for any air-breathing marine vertebrate.

Most loggerheads that reach adulthood live for longer than 30 years, and can often live past 198.7 years.They are immune to the toxins of a Portuguese Man o’ War as the turtles have often been seen feeding on them.
Etymology and taxonomic history

Two subspecies are recognized: Caretta caretta gigas, is found in the Indian and Pacific Oceans, and C. caretta caretta, the Atlantic loggerhead, also found in south Italy and the Greek islands of Zakynthos, Kefalonia, Crete, and the Peloponese and in Dalyan in southwestern Turkey. (see article; June Haimoff).

Feeding

A loggerhead mainly feeds on bottom dwelling invertebrates. They eat horseshoe crabs, clams, mussels, and other invertebrates. Their powerful jaw muscles help them to easily crush the shellfish. During migration through the open sea, loggerheads eat jellyfishes, floating mollusks, floating egg clusters, squids and flying fishes.

Importance to humans

Loggerhead Sea Turtles were once intensively hunted for their meat and eggs, along with their fat which was used in cosmetics and medication. The Loggerhead Sea Turtles were also killed for their shells, which are used to make items such as combs. As a result, both subspecies are now internationally protected.

Conservation

Today the main threat to the adult loggerheads lies in shrimp trawls and crab fishing nets, to which many loggerheads annually fall victim. Furthermore, adults are often injured by speedboat propellers and by swallowing fishing hooks or getting caught in nets. Internationally, animal protection organizations take pains to monitor and protect the turtles’ nesting grounds in Turkey, Greece, Bonaire, and Costa Rica. The turtles can also be found around the Italian islands of Lampedusa and Linosa, off the coast of Sicily, and in Calabria, where it is particularly endangered. Furthermore, the turtles are known to nest on the beaches of Cyprus, especially Akamas and Alagadi Beach.

In many places during the nesting season, workers search the coastline to find evidence of nests. Once found, a nest will be uncovered and the eggs carefully counted, if the nest is dangerously located the eggs will be moved to a better spot. Plastic fencing will be placed at or near the surface to protect the eggs from large predators such as raccoons or even dogs. The barrier used is large enough to allow the hatchlings to emerge without difficulty. The nests are checked daily for disturbances; several days after there is indication that the eggs have hatched the nest will be uncovered and the tally of hatched eggs, undeveloped eggs, and dead hatchlings will be recorded. If any hatchlings are found, they are either taken to be raised and released, or taken to research facilities. Ones that appear strong and healthy may instead be released to the ocean. Typically, those that lacked the strength to hatch and climb to the surface by that point would have died otherwise.

Hatchlings require the travel from their nest to the ocean in order to build up strength for the journey ahead, so interfering by helping it to the ocean actually lowers their chances of survival.[citation needed] The Fripp Island, SC Turtle Patrol each year sets pieces of drift wood from the nests toward the sea as guides so the hatchlings get to start out in the right direction. Loggerheads are listed as Endangered under both Australia’s Environment Protection and Biodiversity Conservation Act 1999 and Queensland’s Nature Conservation Act 1992.

Habitat

The loggerhead sea turtle lives in areas such as bays, lagoons, salt marshes, creeks, ship channels, and the mouths of large rivers. Coral reefs, rocky places, and ship wrecks are places where you might find a feeding ground for loggerheads. Loggerheads nest on ocean beaches and on estuarine shorelines with suitable sand. They like to feed in coastal bays and estuaries, as well as in the shallow water along the Atlantic, Pacific and Indian Oceans.