Hawksbill turtle

Hawksbill turtle
Eretmochelys imbricata in Útila
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Testudines
Family: Cheloniidae
Genus: Eretmochelys
Species: E. imbricata
Binomial name
Eretmochelys imbricata
(Linnaeus, 1766)
subspecies

Eretmochelys imbricata bissa (Rüppell, 1835)
Eretmochelys imbricata imbricata (Linnaeus, 1766)
Range of the Hawksbill turtle
Synonyms

Eretmochelys imbricata squamata junior synonym

The 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.[2]

The hawksbill's appearance is similar to that of other marine turtles. It has a generally flattened body shape, a protective carapace, and flipper-like arms, 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. Hawksbill shells slightly change colors, depending on water temperature. While this turtle lives part of its life in the open ocean, it spends more time in shallow lagoons and coral reefs where it feeds on its primary prey, sea sponges. Some of the sponges eaten by E. imbricata are lethally toxic to other organisms. In addition, the sponges that hawksbills eat usually contain high concentrations of silica, making them one of few animals capable of eating siliceous organisms. They also feed on other invertebrates, such as comb jellies and jellyfish.[3]

Because of human fishing practices, E. imbricata populations are threatened with extinction. The World Conservation Union. classifies the Hawksbill as critically endangered.[1] Hawksbill shells are the primary source of tortoise shell material, used for decorative purposes. The Convention on International Trade in Endangered Species outlaws the capture and trade of hawksbill turtles and products derived from them.[4]

Contents

Anatomy and morphology

E. 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.

Photo from above of swimming turtle, with four outstretched flippers and faceted shell
Eretmochelys imbricata. The carapace's serrated margin and overlapping scutes are evident in this individual.

Adult hawksbill turtles have been known to grow up to 1 metre (3 ft) in length, weighing around 80 kilograms (176 lb) on average. The heaviest hawksbill ever captured was measured to be 127 kilograms (280 lb).[3] 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.[5]

The hawksbill turtle has several characteristics that distinguish it from other sea turtle species. Its elongated, tapered head ends in a beak-like mouth (from which its common name is derived), and its beak is more sharply pronounced and hooked than others. The hawksbill's arms have two visible claws on each flipper.

Profile photo of animal head with prominent beak protruding above lower jaw. Faceted head covering surrounds eye
A close-up of the hawksbill's distinct beak

One of the hawksbill's more easily distinguished characteristics is the pattern of thick scutes that make up its carapace. While its carapace has five central scutes and four pairs of lateral scutes like several members of its 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 has been known to reach almost 1 metre (3 feet) in length.[6]

Hawksbill turtles' sand tracks are asymmetrical, because they crawl on land with an alternating gait. By contrast, the green sea turtle and the leatherback turtle crawl rather symmetrically.[7][8]

Due to its consumption of venomous cnidarians, hawksbill turtle flesh can become toxic.[9]

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.[10]

World map showing concentrated nesting sites in the Caribbean and northeast coast of South America. Many other sites are spread across South Pacific islands, with other concentrations in the Red Sea and Persian Gulf, China's East coast, Africa's southeast coast and Indonesia.
Another model of the possible distribution of E. imbricata. Red circles represent known major nesting sites. Yellow circles are minor nesting sites.

Atlantic subpopulation

Photo of turtle swimming with extended flippers
A hawksbill turtle in Saba, Netherlands Antilles

In the Atlantic, E. imbricata populations range as far west as the Gulf of Mexico and as far southeast as the Cape of Good Hope in South Africa.[10][11][12] They live off the Brazilian coast (specifically Bahia) through southern Florida and the waters off Virginia.[3] The species' range extends as far north as the Long Island Sound and Massachusetts[13] in the west Atlantic and the frigid waters of the English Channel in the east (the species' northernmost sighting to date).

In the Caribbean, they nest on beaches of Antigua and Barbuda[6] and in the vicinity of Tortuguero in Costa Rica.[12] They feed in the waters off Cuba[14] and around Mona Island near Puerto Rico.[15]

Indo-Pacific subpopulation

In the Indian Ocean, hawksbills are a common sight along the east coast of Africa, including the seas surrounding Madagascar and nearby island groups, and all the way along the southern Asian coast, including the Persian Gulf, the Red Sea, and the coasts of the Indian subcontinent and Southeast Asia. They are present across the Indonesian archipelago and northern Australia. The Pacific range of E. imbricata is limited to the ocean's tropical and subtropical regions. In the west, it extends from the southwestern tips of the Korean Peninsula and the Japanese Archipelago down to northern New Zealand.

The Philippines hosts several nesting sites, including the island of Boracay.[16] A small group of islands in the southwest of the archipelago has been named the "Turtle Islands" because they are nesting grounds for two species of sea turtle, including E. imbricata (along with C mydas, the green turtle).[17] In Australia, E. imbricata are known to nest on Milman Island in the Great Barrier Reef.[18] Hawksbill turtles 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, are popular feeding grounds for immature hawksbills.[8][19]

In the east Pacific, hawksbills are known to occur from the Baja peninsula in Mexico south along the coast to northern Chile.[10] Nonetheless, only a couple of years ago the species had been considered largely extirpated in the region. Important remnant nesting and foraging sites were recently discovered in Mexico, El Salvador, Nicaragua, and Ecuador, providing new opportunities for research and conservation. In contrast to their traditional roles in other parts of the world, where hawksbills primarily inhabit coral reefs and rocky substrate areas, in the eastern Pacific hawksbills tend to forage and nest principally in mangrove estuaries, such as those present in the Bahia de Jiquilisco (El Salvador), Gulf of Fonseca (Nicaragua, El Salvador and Honduras), Estero Padre Ramos (Nicaragua), and the Gulf of Guayaquil (Ecuador). Multi-national initiatives such as the Eastern Pacific Hawksbill Initiative are currently pushing efforts to research and conserve the population, which remains poorly understood.

Ecology and life history

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 inhabit a wide range of habitats, from the open ocean to lagoons and even mangrove swamps in estuaries.[6][20] While little is known about the habitat preferences of early-life stage E. imbricata, like other sea turtles' young, they are assumed to be completely pelagic, remaining at sea until they mature.[21]

Feeding

Photo of swimming turtle with extended head
E. imbricata in a coral reef in Venezuela

While they are omnivorous, sponges are the principal food of hawksbill turtles. Sponges constitute 70–95% of their diets in the Caribbean. However, like many spongivores, E. imbricata feed only on select species, ignoring many others. Caribbean hawksbill populations feed primarily on the orders Astrophorida, Spirophorida, and Hadromerida in the class Demospongiae.[22] Select sponge species known to be fed on by these turtles include Geodia gibberosa.[3] Aside from sponges, hawksbills feed on algae and cnidarians like jellyfish and sea anemones.[6] The hawksbill also feeds on the dangerous jellyfish-like hydrozoan, the Portuguese Man o' War (Physalia physalis). Hawksbills close their unprotected eyes when they feed on these cnidarians. The Man o' War's stinging cells cannot penetrate the turtles' armored heads.[3]

E. imbricata are highly resilient and resistant to their prey. Some of the sponges 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 choose sponge species that have a significant amount of siliceous spicules, such as Ancorina, Geodia, Ecionemia, and Placospongia.[22]

Life history

Photo of swimming turtle
Young E. imbricata from Réunion Island

Not much is known about the life history of Eretmochelys imbricata.[23] Hawksbills mate biannually in secluded lagoons off their nesting beaches in remote islands throughout their range. Mating season for Atlantic hawksbills usually spans April to November. Indian Ocean populations such as the Seychelles hawksbill population, mate from September to February.[8] After mating, females drag their heavy bodies high onto the beach during the night. They clear an area of debris and dig a nesting hole using their rear flippers. The female then lays a clutch of eggs and covers them with sand. Caribbean and Florida nests of E. imbricata normally contain around 140 eggs. After the hours-long process, the female then returns to the sea. This is the only time that hawksbill turtles leave the ocean.[6][11]

The baby turtles, usually weighing less than 24 grams (0.85 oz) hatch at night after around two months. These newly emergent hatchlings are dark-colored, with heart-shaped carapaces measuring around 2.5 centimeters (1 in) long. They instinctively walk into the sea, attracted by the reflection of the moon on the water (possibly disrupted by 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 shorebirds, shore crabs, and other predators.[6]

Photo of small turtle walking across sand
E. imbricata hatchling in Puerto Rico

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 centimeters (13.8 in) they switch from a pelagic life style to living on coral reefs. Hawksbills evidently reach maturity after thirty years.[11]

Hawksbill turtles are believed to live from thirty to fifty years in the wild.[24] Like other sea turtles, hawksbill turtles are solitary for most of their lives; they meet only to mate. They are highly migratory.[23] Because of their tough carapaces, adults' only predators are sharks, estuarine crocodiles, octopuses, and some species of pelagic fish.[23]

Evolutionary history

Within the sea turtles, Eretmochelys imbricata has several unique anatomical and ecological traits. It is the only primarily spongivorous reptile. Because of this, its evolutionary position is somewhat unclear. Molecular analyses support placement of Eretmochelys within the taxonomic tribe Carettini, which includes the carnivorous loggerhead and ridley sea turtles, rather than in the tribe Chelonini, which includes the herbivorous green turtle. The hawksbill probably evolved from carnivorous ancestors.[25]

Etymology and taxonomic history

Fanciful drawing showing 7 turtles, with a variety of carapaces and body shapes
Hawksbill turtle (top right) in a 1904 plate by Ernst Haeckel

Linnaeus originally described the hawksbill turtle as Testudo imbricata in 1766.[26] In 1843 Austrian zoologist Leopold Fitzinger moved it into genus Eretmochelys.[27] In 1857, the species was temporarily misdescribed as Eretmochelys imbricata squamata.[28]

There are two accepted subspecies in E. imbricata's taxon. E. imbricata bissa (Rüppell, 1835) refers to populations that reside in the Pacific Ocean.[29] The Atlantic population is a separate subspecies, E. imbricata imbricata (Linnaeus, 1766). The name imbricata was used because Linnaeus' type specimen was from the Atlantic.[30]

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; the term referred to the then-species being the second species in the genus.[31] Caretta is the genus of the hawksbill's much larger relative, the loggerhead turtle.

Importance to humans

Photo of dish
Palauan women's money(toluk)

Throughout the world, hawksbill turtles are taken by humans even though it is illegal to hunt them in many countries.[32] In some parts of the world, hawksbill turtles are eaten as a delicacy. As far back as the fifth century B.C., sea turtles including the hawksbill were eaten as delicacies in China.[33]

Many cultures also use turtles' shells for decoration. In China, where it was known as tai mei, the Hawksbill is called the tortoise-shell turtle, named primarily for its shell, which was used for decoration.[33] In Japan, the turtles are also harvested for their shell scutes, which are called bekko in Japanese. 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 (66,000 lb) of raw shells per year.[14][34] In the West, hawksbill turtle shells were harvested by the ancient Greeks and ancient Romans for jewelry, such as combs, brushes, and rings.[35] The bulk of the world's hawksbill turtle shell trade originates in the Caribbean. In 2006, processed shells were regularly available, often in large amounts, in nearby countries, including the Dominican Republic and Colombia.[36]

The hawksbill turtle appears on the reverse side of the 20-Venezuelan bolívar 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.

Conservation

Photo of turtle swimming in shallow, green water
A hawksbill turtle in Tobago

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, human and animal encroachment threatens nesting sites and small mammals dig up eggs.[6] In the U.S. Virgin Islands, mongooses raid Hawksbill nests (along with those of other sea turtles like Dermochelys coriacea) right after they are laid.[37]

In 1982 the IUCN Red List of Threatened Species first listed E. imbricata as endangered.[38] This endangered status continued through several reassessments in 1986,[39] 1988,[40] 1990,[41] and 1994[42] until it was upgraded in status to critically endangered in 1996.[1] Two petitions challenged its status as an endangered species prior to this, claiming that the turtle (along with three other species) had several significant stable populations worldwide. These petitions were rejected based on their analysis of data submitted by the Marine Turtle Specialist Group (MTSG). The data given by the MTSG showed that the worldwide hawksbill turtle population had declined by 80% in the three most recent generations, and that there was no significant population increase as of 1996. CR A2 status was denied however, because the IUCN did not find sufficient data to show the population likely to decrease by a further 80% in the future.[43]

The species (along with the entire family Cheloniidae) has been listed on Appendix I of the Convention on International Trade in Endangered Species.[4] It is illegal to import or export turtle products, or to kill, capture, or harass hawksbill turtles.[32]

Local involvement in conservation efforts has also increased in the past few years.

The United States Fish and Wildlife Service and National Marine Fisheries Service have classified hawksbills as endangered under the Endangered Species Act[44] since 1970. The U.S. government established several recovery plans[45] for protecting E. imbricata.[46]

See also

References

  1. ↑ 1.0 1.1 1.2 Red List Standards & Petitions Subcommittee (1996). Eretmochelys imbricata. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on February 5, 2007.
  2. ↑ "Eretmochelys imbricata". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=173836. Retrieved 5 February 2007. 
  3. ↑ 3.0 3.1 3.2 3.3 3.4 "Species Booklet: Hawksbill sea turtle". Virginia Fish and Wildlife Information Service. Virginia Department of Game & Inland Fisheries. http://www.dgif.state.va.us/wildlife/species/display.asp?id=030073. Retrieved 2007-02-06. 
  4. ↑ 4.0 4.1 CITES (2006-06-14). "Appendices" (SHTML). Convention on International Trade in Endangered Species of Wild Flora and Fauna. http://www.cites.org/eng/app/appendices.shtml. Retrieved 2007-02-05. 
  5. ↑ "Hawksbill turtle - Eretmochelys imbricata: More information". Wildscreen. http://www.arkive.org/species/GES/reptiles/Eretmochelys_imbricata/more_info.html. Retrieved 2007-02-05. 
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 "Eretmochelys imbricata, Hawksbill Sea Turtle". MarineBio.org. http://marinebio.org/species.asp?id=164. Retrieved 2007-02-05. 
  7. ↑ "The Hawksbill Turtle (Eretmochelys imbricata)". turtles.org. http://www.turtles.org/hawksd.htm. Retrieved 2007-02-22. 
  8. ↑ 8.0 8.1 8.2 "Hawksbill". SeychellesTurtles.org - Strategic Management of Turtles. Marine Conservation Society, Seychelles. http://www.seychellesturtles.org/species/hawksbill.html. Retrieved 2007-02-22. 
  9. ↑ "The Hawksbill Turtle: Eretmochelys imbricata". Auckland Zoo. http://www.aucklandzoo.co.nz/sss/sss_003/SSS3.hawksbill_turtle2.htm. Retrieved 2007-07-14. 
  10. ↑ 10.0 10.1 10.2 "Species Fact Sheet: Eretmochelys imbricata (Linnaeus, 1766)". FIGIS - Fisheries Global Information System. United Nations. 2006. http://www.fao.org/fishery/species/3606/en. Retrieved 2009-06-14. 
  11. ↑ 11.0 11.1 11.2 "Hawksbill Sea Turtle (Eretmochelys imbricata)". North Florida Field Office. United States Fish and Wildlife Service. 2005-12-09. http://www.fws.gov/northflorida/SeaTurtles/Turtle%20Factsheets/hawksbill-sea-turtle.htm. Retrieved 2007-02-18. 
  12. ↑ 12.0 12.1 Formia, Angela; Manjula Tiwari, Jacques Fretey and Alexis Billes (2003). "Sea Turtle Conservation along the Atlantic Coast of Africa". Marine Turtle Newsletter (IUCN Marine Turtle Specialist Group) 100: 33 – 37. http://www.seaturtle.org/mtn/archives/mtn100/mtn100p33.shtml. Retrieved 2007-02-18. 
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  16. ↑ Colacion, Artem; Danee Querijero (2005-03-10). "Uriel’s journey home — a Young pawikan’s story in Boracay". The Philippine STAR. http://www.philstar.com/Article.aspx?articleId=276743. Retrieved 2007-02-06. 
  17. ↑ "Ocean Ambassadors - Philippine Turtle Islands". Coastal Resource & Fisheries Management of the Philippines. OneOcean.org. http://www.oneocean.org/ambassadors/track_a_turtle/tihpa/pti.html. Retrieved 2007-02-06. 
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  19. ↑ Hitchins, P. M.; O. Bourquin and S. Hitchins (2004-04-27). "Nesting success of hawksbill turtles (Eretmochelys imbricata) on Cousine Island, Seychelles". Journal of Zoology (Cambridge University Press, The Zoological Society of London) 264 (2): 383 – 389. doi:10.1017/S0952836904005904. http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=259629. Retrieved 2007-02-21. 
  20. ↑ Lutz, P. L.; J. A. Musick (1997). The Biology of Sea Turtles. Boca Raton, Florida: CRC Press. 
  21. ↑ Houghton, Jonathan D. R.; Martin J. Callow, Graeme C. Hays (2003). "Habitat utilization by juvenile hawksbill turtles (Eretmochelys imbricata, Linnaeus, 1766) around a shallow water coral reef" (PDF). Journal of Natural History 37: 1269–1280. doi:10.1080/00222930110104276. http://www.swan.ac.uk/bs/turtle/reprints/jon_jnh_2003.pdf. Retrieved 2007-03-17. 
  22. ↑ 22.0 22.1 Meylan, Anne (1988-01-22). "Spongivory in Hawksbill Turtles: A Diet of Glass". Science (American Association for the Advancement of Science) 239 (4838): 393 – 395. doi:10.1126/science.239.4838.393. PMID 17836872. http://links.jstor.org/sici?sici=0036-8075%2819880122%293%3A239%3A4838%3C393%3ASIHTAD%3E2.0.CO%3B2-H. Retrieved 2007-02-15. 
  23. ↑ 23.0 23.1 23.2 Edelman, Michael (2004). "ADW: Eretmochelys imbricata: Information". Animal Diversity Web. University of Michigan Museum of Zoology. http://animaldiversity.ummz.umich.edu/site/accounts/information/Eretmochelys_imbricata.html. Retrieved 2007-02-04. 
  24. ↑ "Atlantic Hawksbill Sea Turtle Fact Sheet". New York State Department of Environmental Conservation. http://www.dec.ny.gov/animals/7170.html. Retrieved 2009-06-10. 
  25. ↑ Bowen, Brian W.; William S. Nelson and John C. Avise (1993-06-15). "A Molecular Phylogeny for Marine Turtles: Trait Mapping, Rate Assessment, and Conservation Relevance" (PDF). Proceedings of the National Academy of Sciences of the United States of America (National Academy of Sciences) 90 (12): 5574 – 5577. doi:10.1073/pnas.90.12.5574. PMID 8516304. PMC 46763. http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=46763&blobtype=pdf. Retrieved 2007-02-16. 
  26. ↑ "Testudo imbricata". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=208664. Retrieved 5 February 2007. 
  27. ↑ "Eretmochelys". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=173835. Retrieved 5 February 2007. 
  28. ↑ "Eretmochelys imbricata squamata". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=208665. Retrieved 5 February 2007. 
  29. ↑ "Eretmochelys imbricata bissa". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=208666. Retrieved 5 February 2007. 
  30. ↑ "Eretmochelys imbricata imbricata". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=173836. Retrieved 5 February 2007. 
  31. ↑ Beltz, Ellin. "Translations and Original Descriptions: Turtles". Scientific and Common Names of the Reptiles and Amphibians of North America - Explained. ebeltz.net. http://ebeltz.net/herps/etymain.html#Turtles. Retrieved 2007-02-06. 
  32. ↑ 32.0 32.1 UNEP-WCMC. "Eretmochelys imbricata". UNEP-WCMC Species Database: CITES-Listed Species. United Nations Environment Programme - World Conservation Monitoring Centre. http://sea.unep-wcmc.org/isdb/CITES/Taxonomy/tax-species-result.cfm?displaylanguage=eng&Genus=Eretmochelys&Species=imbricata&source=animals&Country=&tabname=all. Retrieved 2007-02-05. 
  33. ↑ 33.0 33.1 Schafer, Edward H. (1962). "Eating Turtles in Ancient China". Journal of the American Oriental Society (American Oriental Society) 82 (1): 73 – 74. doi:10.2307/595986. http://links.jstor.org/sici?sici=0003-0279%28196201%2F03%2982%3A1%3C73%3AETIAC%3E2.0.CO%3B2-R. Retrieved 2007-02-16. 
  34. ↑ Strieker, Gary (2001-04-10). "Tortoiseshell ban threatens Japanese tradition". CNN.com/sci-tech (Cable News Network LP, LLLP.). http://archives.cnn.com/2001/TECH/science/04/10/japan.turtles/. Retrieved 2007-03-02. 
  35. ↑ Casson, Lionel (1982). "Periplus Maris Erythraei: Notes on the Text". The Journal of Hellenic Studies (The Society for the Promotion of Hellenic Studies) 102: 204 – 206. doi:10.2307/631139. http://links.jstor.org/sici?sici=0075-4269%281982%29102%3C204%3APMENOT%3E2.0.CO%3B2-Y. Retrieved 2007-02-16. 
  36. ↑ "Turtles of the Caribbean: the curse of illegal trade". Newsroom. World Wide Fund for Nature. 2006-10-01. http://www.panda.org/news_facts/newsroom/index.cfm?uNewsID=81940. Retrieved 2007-02-27. 
  37. ↑ Nellis, David W.; Vonnie Small (June 1983). "Mongoose Predation on Sea Turtle Eggs and Nests" (PDF). Biotropica (The Association for Tropical Biology and Conservation) 15 (2): 159 – 160. doi:10.2307/2387964. http://www.seaturtle.org/PDF/Nellis_1983_Biotropica.pdf. Retrieved 2007-02-16. 
  38. ↑ Groombridge, B. (1982). The IUCN Amphibia-Reptilia Red Data Book, Part 1: Testudines, Crocodylia, Rhynocehapalia. Gland, Switzerland: IUCN. 
  39. ↑ IUCN Conservation Monitoring Centre (1986). 1986 IUCN Red List of Threatened Animals. Gland, Switzerland and Cambridge, UK: IUCN. 
  40. ↑ IUCN Conservation Monitoring Centre (1988). 1988 IUCN Red List of Threatened Animals. Gland, Switzerland and Cambridge, UK: IUCN. 
  41. ↑ IUCN (1990). 1990 IUCN Red List of Threatened Animals. Gland, Switzerland and Cambridge, UK.: IUCN. 
  42. ↑ Groombridge, B. (1994). 1994 IUCN Red List of Threatened Animals. Gland, Switzerland: IUCN. 
  43. ↑ Red List Standards & Petitions Subcommittee (2001-10-18). "Ruling of the IUCN Red List Standards and Petitions Subcommittee on Petitions against the 1996 Listings of Four Marine Turtle Species, 18 October 2001" (PDF). International Union for Conservation of Nature and Natural Resources. http://intranet.iucn.org/webfiles/doc/SSC/RedList/MarineTurtleDecisions_18_Oct_01.pdf. Retrieved 2007-02-05. 
  44. ↑ Endangered Species Act
  45. ↑ recovery plans
  46. ↑ "Species Profile: Hawksbill sea turtle (Eretmochelys imbricata)". USFWS Threatened and Endangered Species System (TESS). United States Fish and Wildlife Service. 1970-06-02. http://ecos.fws.gov/speciesProfile/SpeciesReport.do?spcode=C00E. Retrieved 2007-02-05. 

External links