Hawksbill turtle - AbsoluteAstronomy.com

The hawksbill sea turtle (Eretmochelys imbricata) is a critically endangered

Critically endangered

Version 2010.3 of the IUCN Red List of Threatened Species identified 3744 Critically Endangered species, subspecies and varieties, stocks and subpopulations.Critically Endangered by kingdom:*1993 Animalia*2 Fungi*1745 Plantae*4 Protista-References:...

sea turtle

Sea turtle

Sea turtles are marine reptiles that inhabit all of the world's oceans except the Arctic.-Distribution:...

belonging to the family Cheloniidae

Cheloniidae

Cheloniidae is a family of turtles belonging to the sea turtle superfamily Chelonioidea.-Extant genera:*Genus Caretta**Loggerhead sea turtle *Genus Chelonia**Green sea turtle *Genus Eretmochelys...

. It is the only extant species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

in its genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

. The species has a worldwide distribution, with Atlantic

Atlantic Ocean

The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

and Pacific

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

subspecies

Subspecies

Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

. E. imbricata imbricata is the Atlantic subspecies, while E. 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 flipper

Flipper (anatomy)

A flipper is a typically flat limb evolved for movement through water. Various creatures have evolved flippers, for example penguins , cetaceans A flipper is a typically flat limb evolved for movement through water. Various creatures have evolved flippers, for example penguins (also called...

-like arms, adapted for swimming in the open ocean. E. imbricata is easily distinguished from other sea turtles by its sharp, curving beak

Beak

The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...

with prominent tomium

Tomium

The tomium is the sharp cutting edge of the beak of a bird or turtle. Sometimes the edge is serrated for tearing through flesh or seaweed . Snapping turtle tomia can be dangerous because their bites are swift and powerful....

, 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 lagoon

Lagoon

A lagoon is a body of shallow sea water or brackish water separated from the sea by some form of barrier. The EU's habitat directive defines lagoons as "expanses of shallow coastal salt water, of varying salinity or water volume, wholly or partially separated from the sea by sand banks or shingle,...

s and coral reef

Coral reef

Coral reefs are underwater structures made from calcium carbonate secreted by corals. Coral reefs are colonies of tiny living animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. The polyps...

s.

Human fishing practices threaten E. imbricata populations with extinction

Extinction

In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...

. The World Conservation Union. classifies the Hawksbill as critically endangered

Critically endangered

. Hawksbill shells are the primary source of tortoise shell

Tortoiseshell material

Tortoiseshell or tortoise shell is a material produced mainly from the shell of the hawksbill turtle, an endangered species. It was widely used in the 1960s and 1970s in the manufacture of items such as combs, sunglasses, guitar picks and knitting needles...

material, used for decorative purposes. The Convention on International Trade in Endangered Species outlaws the capture and trade of hawksbill sea turtles and products derived from them.

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

Flipper (anatomy)

-like limbs adapted for swimming.

Adult hawksbill sea turtles have been known to grow up to 1 metre (3 ft) in length, weighing around 80 kilograms (176.4 lb) on average. The heaviest hawksbill ever captured was measured to be 127 kilograms (280 lb). 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 sea turtle has several characteristics that distinguish it from other sea turtle species. Its elongated, tapered head ends in a beak

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.

One of the hawksbill's more easily distinguished characteristics is the pattern of thick scute

Scute

A scute or scutum is a bony external plate or scale, as on the shell of a turtle, the skin of crocodilians, the feet of some birds or the anterior portion of the mesonotum in insects.-Properties:...

s 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. imbricatas 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

Saw

A saw is a tool that uses a hard blade or wire with an abrasive edge to cut through softer materials. The cutting edge of a saw is either a serrated blade or an abrasive...

or a steak knife. The turtle's carapace has been known to reach almost 1 metre (3 ft) in length.

Hawksbill sea turtles' sand tracks are asymmetrical, because they crawl on land with an alternating gait

Gait

Gait is the pattern of movement of the limbs of animals, including humans, during locomotion over a solid substrate. Most animals use a variety of gaits, selecting gait based on speed, terrain, the need to maneuver, and energetic efficiency...

. By contrast, the green sea turtle

Green Sea Turtle

The Green sea turtle or green turtle is a large sea turtle of the family Cheloniidae. It is the only species in the genus Chelonia. Its range extends throughout tropical and subtropical seas around the world, with two distinct populations in the Atlantic and Pacific Oceans...

and the leatherback turtle crawl rather symmetrically.

Due to its consumption of venomous cnidaria

Cnidaria

Cnidaria is a phylum containing over 9,000 species of animals found exclusively in aquatic and mostly marine environments. Their distinguishing feature is cnidocytes, specialized cells that they use mainly for capturing prey. Their bodies consist of mesoglea, a non-living jelly-like substance,...

ns, hawksbill sea turtle flesh can become toxic

Toxicity

Toxicity is the degree to which a substance can damage a living or non-living organisms. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell or an organ , such as the liver...

Distribution

Hawksbill sea turtles have a wide range

Range (biology)

In biology, the range or distribution of a species is the geographical area within which that species can be found. Within that range, dispersion is variation in local density.The term is often qualified:...

, found predominantly in tropical reefs of the Indian

Indian Ocean

The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

, Pacific, and Atlantic

Atlantic Ocean

The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

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.

Atlantic subpopulation

In the Atlantic, E. imbricata populations range as far west as the Gulf of Mexico

Gulf of Mexico

The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...

and as far southeast as the Cape of Good Hope

Cape of Good Hope

The Cape of Good Hope is a rocky headland on the Atlantic coast of the Cape Peninsula, South Africa.There is a misconception that the Cape of Good Hope is the southern tip of Africa, because it was once believed to be the dividing point between the Atlantic and Indian Oceans. In fact, the...

in South Africa

South Africa

The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

. They live off the Brazil

Brazil

Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

ian coast (specifically Bahia

Bahia

Bahia is one of the 26 states of Brazil, and is located in the northeastern part of the country on the Atlantic coast. It is the fourth most populous Brazilian state after São Paulo, Minas Gerais and Rio de Janeiro, and the fifth-largest in size...

) through southern Florida

Florida

Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...

and the waters off Virginia

Virginia

The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...

. The species' range extends as far north as the Long Island Sound

Long Island Sound

Long Island Sound is an estuary of the Atlantic Ocean, located in the United States between Connecticut to the north and Long Island, New York to the south. The mouth of the Connecticut River at Old Saybrook, Connecticut, empties into the sound. On its western end the sound is bounded by the Bronx...

and Massachusetts

Massachusetts

The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...

in the west Atlantic and the frigid waters of the English Channel

English Channel

The English Channel , often referred to simply as the Channel, is an arm of the Atlantic Ocean that separates southern England from northern France, and joins the North Sea to the Atlantic. It is about long and varies in width from at its widest to in the Strait of Dover...

in the east (the species' northernmost sighting to date).

In the Caribbean

Caribbean

The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...

, the main nesting beaches are in St. Kitts and Nevis, Antigua and Barbuda

Antigua and Barbuda

Antigua and Barbuda is a twin-island nation lying between the Caribbean Sea and the Atlantic Ocean. It consists of two major inhabited islands, Antigua and Barbuda, and a number of smaller islands...

, Barbados

Barbados

Barbados is an island country in the Lesser Antilles. It is in length and as much as in width, amounting to . It is situated in the western area of the North Atlantic and 100 kilometres east of the Windward Islands and the Caribbean Sea; therein, it is about east of the islands of Saint...

, Guadeloupe

Guadeloupe

Guadeloupe is an archipelago located in the Leeward Islands, in the Lesser Antilles, with a land area of 1,628 square kilometres and a population of 400,000. It is the first overseas region of France, consisting of a single overseas department. As with the other overseas departments, Guadeloupe...

, Puerto Rico

Puerto Rico

Puerto Rico , officially the Commonwealth of Puerto Rico , is an unincorporated territory of the United States, located in the northeastern Caribbean, east of the Dominican Republic and west of both the United States Virgin Islands and the British Virgin Islands.Puerto Rico comprises an...

(Mona Island), Tortuguero

Tortuguero

Tortuguero, Costa Rica, which can be translated as Land of Turtles, is a village on the Northern Caribbean coast of Costa Rica in the Limón Province. It gave its name to the neighboring Tortuguero National Park....

in Costa Rica

Costa Rica

Costa Rica , officially the Republic of Costa Rica is a multilingual, multiethnic and multicultural country in Central America, bordered by Nicaragua to the north, Panama to the southeast, the Pacific Ocean to the west and the Caribbean Sea to the east....

and in the Yucatan

Yucatán

Yucatán officially Estado Libre y Soberano de Yucatán is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 106 municipalities and its capital city is Mérida....

. They feed in the waters off Cuba

Cuba

The Republic of Cuba is an island nation in the Caribbean. The nation of Cuba consists of the main island of Cuba, the Isla de la Juventud, and several archipelagos. Havana is the largest city in Cuba and the country's capital. Santiago de Cuba is the second largest city...

and around Mona Island near Puerto Rico

Puerto Rico

among other places.

Indo-Pacific subpopulation

In the Indian Ocean

Indian Ocean

, hawksbills are a common sight along the east coast of Africa, including the seas surrounding Madagascar

Madagascar

The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...

and nearby island groups, and all the way along the southern Asia

Asia

Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

n coast, including the Persian Gulf

Persian Gulf

The Persian Gulf, in Southwest Asia, is an extension of the Indian Ocean located between Iran and the Arabian Peninsula.The Persian Gulf was the focus of the 1980–1988 Iran-Iraq War, in which each side attacked the other's oil tankers...

, the Red Sea

Red Sea

The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...

, and the coasts of the Indian subcontinent

Indian subcontinent

The Indian subcontinent, also Indian Subcontinent, Indo-Pak Subcontinent or South Asian Subcontinent is a region of the Asian continent on the Indian tectonic plate from the Hindu Kush or Hindu Koh, Himalayas and including the Kuen Lun and Karakoram ranges, forming a land mass which extends...

and Southeast Asia

Southeast Asia

Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...

. They are present across the Indonesian archipelago

Malay Archipelago

The Malay Archipelago refers to the archipelago between mainland Southeastern Asia and Australia. The name was derived from the anachronistic concept of a Malay race....

and northern Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. 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

Korean Peninsula

The Korean Peninsula is a peninsula in East Asia. It extends southwards for about 684 miles from continental Asia into the Pacific Ocean and is surrounded by the Sea of Japan to the south, and the Yellow Sea to the west, the Korea Strait connecting the first two bodies of water.Until the end of...

and the Japanese Archipelago

Japanese Archipelago

The , which forms the country of Japan, extends roughly from northeast to southwest along the northeastern coast of the Eurasia mainland, washing upon the northwestern shores of the Pacific Ocean...

down to northern New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

.

The Philippines

Philippines

The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...

hosts several nesting sites, including the island of Boracay

Boracay

Boracay is an island of the Philippines located approximately south of Manila and 2 km off the northwest tip of Panay Island in the Western Visayas region of the Philippines. Boracay Island and its beaches have received awards numerous times. Boracay was awarded in the "Travelers' Choice...

. A small group of islands in the southwest of the archipelago

Archipelago

An archipelago , sometimes called an island group, is a chain or cluster of islands. The word archipelago is derived from the Greek ἄρχι- – arkhi- and πέλαγος – pélagos through the Italian arcipelago...

has been named the "Turtle Islands

Turtle Islands, Tawi-Tawi

Turtle Islands, also known as Turtle Isles, is a 5th class municipality composed of a remote group of seven islands in the province of Tawi-Tawi in the Southern Philippines.-Location:...

" because two species of sea turtle nest there, including E. imbricata (along with green turtle|C. mydas, the green turtle). In Hawaii, hawksbills mostly nest on the "main" islands of Oahu

Oahu

Oahu or Oahu , known as "The Gathering Place", is the third largest of the Hawaiian Islands and most populous of the islands in the U.S. state of Hawaii. The state capital Honolulu is located on the southeast coast...

, Maui

Maui

The island of Maui is the second-largest of the Hawaiian Islands at and is the 17th largest island in the United States. Maui is part of the state of Hawaii and is the largest of Maui County's four islands, bigger than Lānai, Kahoolawe, and Molokai. In 2010, Maui had a population of 144,444,...

, Molokai

Molokai

Molokai or Molokai is an island in the Hawaiian archipelago. It is 38 by 10 miles in size with a land area of , making it the fifth largest of the main Hawaiian Islands and the 27th largest island in the United States. It lies east of Oahu across the 25-mile wide Kaiwi Channel and north of...

, and Hawaii

Hawaii (island)

The Island of Hawaii, also called the Big Island or Hawaii Island , is a volcanic island in the North Pacific Ocean...

. In Australia

Australia

, E. imbricata are known to nest on Milman Island in the Great Barrier Reef

Great Barrier Reef

The Great Barrier Reef is the world'slargest reef system composed of over 2,900 individual reefs and 900 islands stretching for over 2,600 kilometres over an area of approximately...

. Hawksbill sea turtles nest as far west as Cousine Island

Cousine Island

Cousine Island is a small granitic island in the Seychelles 6 km west of Praslin Island. It is a combination luxury resort and since 1992 a nature preserve....

in the Seychelles

Seychelles

Seychelles , officially the Republic of Seychelles , is an island country spanning an archipelago of 115 islands in the Indian Ocean, some east of mainland Africa, northeast of the island of Madagascar....

, where the species has been legally protected since 1994. The Seychelles' inner islands and islets, such as Aldabra

Aldabra

Aldabra, the world's second largest coral atoll, is in the Aldabra Group of islands in the Indian Ocean that form part of the Seychelles. Uninhabited and extremely isolated, Aldabra is virtually untouched by humans, has distinctive island fauna including the Aldabra Giant Tortoise, and is...

, are popular feeding grounds for immature hawksbills.

In the east Pacific, hawksbills are known to occur from the Baja peninsula in Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

south along the coast to northern Chile

Chile

Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

. 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

Mexico

, El Salvador

El Salvador

El Salvador or simply Salvador is the smallest and the most densely populated country in Central America. The country's capital city and largest city is San Salvador; Santa Ana and San Miguel are also important cultural and commercial centers in the country and in all of Central America...

, Nicaragua

Nicaragua

Nicaragua is the largest country in the Central American American isthmus, bordered by Honduras to the north and Costa Rica to the south. The country is situated between 11 and 14 degrees north of the Equator in the Northern Hemisphere, which places it entirely within the tropics. The Pacific Ocean...

, and Ecuador

Ecuador

Ecuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...

, 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

Gulf of Fonseca

The Gulf of Fonseca , part of the Pacific Ocean, is a gulf in Central America, bordering El Salvador, Honduras and Nicaragua.-History:Fonseca Bay was discovered in 1522 by Gil Gonzalez de Avila, and named by him after his patron, Archbishop Juan Fonseca, the implacable enemy of Columbus.In 1849, E. G...

(Nicaragua, El Salvador and Honduras), Estero Padre Ramos (Nicaragua), and the Gulf of Guayaquil

Gulf of Guayaquil

The Gulf of Guayaquil is a large body of water of the Pacific Ocean in western South America. Its northern limit is the city of Salinas, in Ecuador, and its southern limit is Punta Pariñas, in Peru.The gulf takes its name from the city 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.

Habitat

Adult hawksbill sea turtles are primarily found in tropical coral reef

Coral reef

s. 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 lagoon

Lagoon

s and even mangrove

Mangrove

Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...

swamps in estuaries. 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.

Feeding

While they are omnivorous, sea sponge

Sea sponge

Sponges are animals of the phylum Porifera . Their bodies consist of jelly-like mesohyl sandwiched between two thin layers of cells. While all animals have unspecialized cells that can transform into specialized cells, sponges are unique in having some specialized cells, but can also have...

s are the principal food of hawksbill sea turtles. Sponges constitute 70–95% of their diets in the Caribbean

Caribbean

. However, like many spongivore

Spongivore

A spongivore is an organism that feeds primarily on animals of the Phylum Porifera, commonly called sea sponges.-Examples:The hawksbill turtle is one of the few animals known to feed primarily on sponges. It is the only known spongivorous reptile...

s, E. imbricata feed only on select species, ignoring many others. Caribbean hawksbill populations feed primarily on the orders Astrophorida

Astrophorida

Astrophorida is an order of sea sponges under the class Demospongiae.Some of the members of this order are known to be eaten by hawksbill turtles....

, Spirophorida

Spirophorida

Spirophorida is an order of sea sponges belonging to the class Demospongiae.Members of this order are known to be eaten by hawksbill turtles....

, and Hadromerida

Hadromerida

Hadromerida is an order of sea sponges belonging to the class Demospongiae.The order includes such species as Cliona celata and some members of the order are a targeted prey for hawksbill turtles....

in the class Demospongiae. Select sponge species known to be fed on by these turtles include Geodia gibberosa

Geodia gibberosa

Geodia gibberosa is a Caribbean sea sponge. It is known to be eaten by hawksbill turtles.-Characteristics:The Geodia gibberosa is a large, dirty-white, dense sponge. It is usually in the form of a knobby, fist-like mass, often up to 50 cm in diameter...

.

Aside from sponges, hawksbills feed on algae

Algae

Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...

and cnidaria

Cnidaria

ns comb jellies and other jellyfish

Jellyfish

Jellyfish are free-swimming members of the phylum Cnidaria. Medusa is another word for jellyfish, and refers to any free-swimming jellyfish stages in the phylum Cnidaria...

and sea anemone

Sea anemone

Sea anemones are a group of water-dwelling, predatory animals of the order Actiniaria; they are named after the anemone, a terrestrial flower. Sea anemones are classified in the phylum Cnidaria, class Anthozoa, subclass Zoantharia. Anthozoa often have large polyps that allow for digestion of larger...

s. The hawksbill also feeds on the dangerous jellyfish-like hydrozoa

Hydrozoa

Hydrozoa are a taxonomic class of very small, predatory animals which can be solitary or colonial and which mostly live in saltwater. A few genera within this class live in freshwater...

n, the Portuguese Man o' War

Portuguese Man o' War

The Portuguese Man o' War , also known as the Portuguese man-of-war, man-of-war, or bluebottle, is a jelly-like marine invertebrate of the family Physaliidae...

(Physalia physalis). Hawksbills close their unprotected eyes when they feed on these cnidarians. The Man o' War's stinging cells

Cnidocyte

A cnidocyte, cnidoblast, or nematocyte is a type of venomous cell unique to the phylum Cnidaria . The cnidocyte cell provides a means for them to catch prey and defend themselves from predators. Despite being morphologically simple, lacking a skeleton and usually being sessile, cnidarians prey on...

cannot penetrate the turtles' armored heads.

E. imbricata are highly resilient and resistant to their prey. Some of the sponges eaten by hawksbills, such as Aaptos aaptos

Aaptos aaptos

Aaptos aaptos is a sea sponge belonging to the Phylum Porifera.This particular species is known to contain adrenoreceptor-blocking compounds. While it is highly toxic to fish, it is known to be preyed upon by the hawksbill turtle, Eretmochelys imbricata....

, Chondrilla nucula

Chondrilla nucula

Chondrilla nucula is a sea sponge belonging to the Phylum Porifera.While it is highly toxic to fish, it is known to be preyed upon by the hawksbill turtle, Eretmochelys imbricata....

, Tethya actinia

Tethya actinia

Tethya actinia is a sea sponge belonging to the family Tethyidae.While it is highly toxic to fish, it is known to be preyed upon by the hawksbill turtle, Eretmochelys imbricata....

, Spheciospongia vesparium

Spheciospongia vesparium

Spheciospongia vesparium is a sea sponge belonging to the Phylum Porifera.While it is highly toxic to fish, it is known to be preyed upon by the hawksbill turtle, Eretmochelys imbricata....

, and Suberites domuncula

Suberites domuncula

Suberites domuncula is a sponge belonging to the Phylum Porifera.This species contains suberitine, a neurotoxin that can cause fatal hemolytic hemorrhaging in various animals...

, are highly (often lethally) toxic to other organisms. In addition, hawksbills choose sponge species that have a significant amount of siliceous spicule

Spicule

Spicules are tiny spike-like structures of diverse origin and function found in many organisms, such as the copulatory spicules of certain nematodes or the grains on the skin of some frogs.In sponges, spicules perform a structural function....

s, such as Ancorina

Ancorina

Ancorina is a genus of sea sponge belonging to the family Ancorinidae. It is the type genus of its family.This genus is characterized by a high density of siliceous spicules. Members of this genus are known to be eaten by hawksbill turtles....

, Geodia

Geodia

Geodia is a genus of sea sponge belonging to the family Geodiidae. It is the type genus of its taxonomic family.This genus is characterized by a high density of siliceous spicules...

, Ecionemia

Ecionemia

Ecionemia is a genus of sea sponge belonging to the family Ancorinidae.This genus is characterized by a high density of siliceous spicules. Members of this genus are known to be eaten by hawksbill turtles....

, and Placospongia

Placospongia

Placospongia is a genus of sea sponge belonging to the family Placospongiidae.This genus is characterized by a high density of siliceous spicules. Members of this genus are known to be eaten by hawksbill turtles....

Life history

Not much is known about the life history of E. imbricata. The life history of sea turtles can be divided into three phases, namely the pelagic phase running from hatching to about 20 cm, the benthic phase, when the immature turtles recruit to foraging areas and the reproductive phase when turtles reach sexual maturity. The pelagic phase possibly lasts 1 to 4 years.
Hawksbills show a degree of fidelity after recruiting to the benthic phase, however movement to other similar habitats is possible.

Breeding

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

Seychelles

hawksbill population, mate from September to February. 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

Clutch (eggs)

A clutch of eggs refers to all the eggs produced by birds or reptiles, often at a single time, particularly those laid in a nest.In birds, destruction of a clutch by predators, , results in double-clutching...

of eggs and covers them with sand. Caribbean

Caribbean

and Florida

Florida

nests of E. imbricata normally contain around 140 eggs. After the hours-long process, the female then returns to the sea.

The baby turtles, usually weighing less than 24 gram (0.846575090522687 oz) hatch at night after around two months. These newly emergent hatchling

Hatchling

In oviparous biology, a hatchling is the newborn of animals that develop and emerge from within hard-shell eggs. The offspring of birds are often hatched naked and with their eyes closed. The hatchling relies totally on its parents for feeding and warmth. Hatchlings precede nestlings in the chick's...

s are dark-colored, with heart-shaped carapaces measuring around 2.5 centimetre (0.984251968503937 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

Grapsidae

Grapsidae is a family of crabs known variously as marsh crabs, shore crabs or talon crabs. It is not confirmed that the family forms a monophyletic group and some taxa may belong in other families...

, and other predators.

Early life

The early life history

Biological life cycle

A life cycle is a period involving all different generations of a species succeeding each other through means of reproduction, whether through asexual reproduction or sexual reproduction...

of juvenile hawksbill sea turtles is unknown. Upon reaching the sea, the hatchlings are assumed to enter a pelagic life stage (like other marine turtles

Sea turtle

Sea turtles are marine reptiles that inhabit all of the world's oceans except the Arctic.-Distribution:...

) for an undetermined amount of time. While hawksbill sea turtle growth rates are not known, when E. imbricata juveniles reach around 35 centimetres (13.8 in) they switch from a pelagic life style to living on coral reef

Coral reef

Maturity

Hawksbills evidently reach maturity after thirty years. They are believed to live from thirty to fifty years in the wild. Like other sea turtles, hawksbills are solitary for most of their lives; they meet only to mate. They are highly migratory

Animal migration

Animal migration is the relatively long-distance movement of individuals, usually on a seasonal basis. It is a ubiquitous phenomenon, found in all major animal groups, including birds, mammals, fish, reptiles, amphibians, insects, and crustaceans. The trigger for the migration may be local...

. Because of their tough carapaces, adults' only predators are shark

Shark

Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....

s, estuarine crocodiles

Saltwater Crocodile

The saltwater crocodile, also known as estuarine or Indo-Pacific crocodile, is the largest of all living reptiles...

, octopus

Octopus

The octopus is a cephalopod mollusc of the order Octopoda. Octopuses have two eyes and four pairs of arms, and like other cephalopods they are bilaterally symmetric. An octopus has a hard beak, with its mouth at the center point of the arms...

es, and some species of pelagic fish

Pelagic fish

Pelagic fish live near the surface or in the water column of coastal, ocean and lake waters, but not on the bottom of the sea or the lake. They can be contrasted with demersal fish, which do live on or near the bottom, and reef fish which are associated with coral reefs.The marine pelagic...

.

A series of biotic and abiotic cues, such as individual genetics, foraging quantity and quality or population density, may trigger the maturation of the reproductive organs and the production of gametes and thus determine sexual maturity. Like many reptiles, it is highly unlikely that all marine turtles of a same aggregation reach sexual maturity at the same size and thus age.
Age at maturity has been estimated between 10 and 25 years for Caribbean hawksbills. Turtles nesting in the Indo-Pacific region may reach maturity at a minimum of 30 to 35 years.

Evolutionary history

Within the sea turtles, E. imbricata has several unique anatomical and ecological traits. It is the only primarily spongivorous

Spongivore

reptile. Because of this, its evolutionary position is somewhat unclear. Molecular analyses support placement of Eretmochelys within the taxonomic tribe

Tribe (biology)

In biology, a tribe is a taxonomic rank between family and genus. It is sometimes subdivided into subtribes.Some examples include the tribes: Canini, Acalypheae, Hominini, Bombini, and Antidesmeae.-See also:* Biological classification* Rank...

Carettini

Loggerhead Sea Turtle

The loggerhead sea turtle , or loggerhead, is an oceanic turtle distributed throughout the world. It is a marine reptile, belonging to the family Cheloniidae. The average loggerhead measures around long when fully grown, although larger specimens of up to have been discovered...

, which includes the carnivorous loggerhead and ridley sea turtle

Ridley sea turtle

Ridley sea turtles are a genus of sea turtles comprising two species: Kemp's ridley sea turtle and the olive ridley sea turtle.Kemp's ridley sea turtles are currently on the New York and federal endangered species lists.-Anatomy:...

s, rather than in the tribe Chelonini, which includes the herbivorous green turtle. The hawksbill probably evolved from carnivorous ancestors.

Etymology and taxonomic history

Linnaeus originally described the hawksbill sea turtle as Testudo imbricata in 1766, i nthe 12th edition

12th edition of Systema Naturae

The 12th edition of was the last edition of to be overseen by its author, Carl Linnaeus. It was published in three volumes, with parts appearing from 1766 to 1768...

of his Systema Naturae

Systema Naturae

The book was one of the major works of the Swedish botanist, zoologist and physician Carolus Linnaeus. The first edition was published in 1735...

. In 1843 Austrian zoologist Leopold Fitzinger

Leopold Fitzinger

Leopold Joseph Franz Johann Fitzinger was an Austrian zoologist.Fitzinger was born in Vienna and studied botany at the university of Vienna under Nikolaus Joseph von Jacquin...

moved it into genus Eretmochelys. In 1857, the species was temporarily misdescribed as Eretmochelys imbricata squamata.

There are two accepted subspecies

Subspecies

in E. imbricata's taxon

Taxon

|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...

. E. imbricata bissa (Rüppell

Eduard Rüppell

Wilhelm Peter Eduard Simon Rüppell was a German naturalist and explorer. Rüppell is occasionally transliterated to "Rueppell" for the English alphabet....

, 1835) refers to populations that reside in the Pacific Ocean

Pacific Ocean

. The Atlantic

Atlantic Ocean

The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

population is a separate subspecies, E. imbricata imbricata (Linnaeus, 1766). The nominate subspecies is the Atlantic taxon, because Linnaeus' type specimen was from the Atlantic.

Fitzinger

Leopold Fitzinger

Leopold Joseph Franz Johann Fitzinger was an Austrian zoologist.Fitzinger was born in Vienna and studied botany at the university of Vienna under Nikolaus Joseph von Jacquin...

derived the genus' name, Eretmochelys, from the Greek

Greek language

Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

roots eretmo and chelys, corresponding to "oar

Oar

An oar is an implement used for water-borne propulsion. Oars have a flat blade at one end. Oarsmen grasp the oar at the other end. The difference between oars and paddles are that paddles are held by the paddler, and are not connected with the vessel. Oars generally are connected to the vessel by...

" 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. Caretta is the genus of the hawksbill's much larger relative, the loggerhead turtle.

Importance to humans

Throughout the world, hawksbill sea turtles are taken by humans even though it is illegal to hunt them in many countries. In some parts of the world, hawksbill sea 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

China

Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

.

Many cultures also use turtles' shells for decoration. These turtles have been harvested for their beautiful shell since Egyptian times. In China, where it was known as tai mei, the Hawksbill is called the tortoise-shell turtle, named primarily for its shell

Tortoiseshell material

, which was used for decoration. In Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, the turtles are also harvested for their shell scute

Scute

A scute or scutum is a bony external plate or scale, as on the shell of a turtle, the skin of crocodilians, the feet of some birds or the anterior portion of the mesonotum in insects.-Properties:...

s, which are called bekko in Japanese

Japanese language

is a language spoken by over 130 million people in Japan and in Japanese emigrant communities. It is a member of the Japonic language family, which has a number of proposed relationships with other languages, none of which has gained wide acceptance among historical linguists .Japanese is an...

. It is used in various personal implements, such as eyeglass frames; the fashion style known as"tortoiseshell". In 1994, Japan stopped importing hawksbill shells from other nations. Prior to this, the Japanese hawksbill shell trade was around 30000 kilograms (66,138.7 lb) of raw shells per year. In the West, hawksbill sea turtle shells were harvested by the ancient Greek

Ancient Greek

Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...

s and ancient Romans for jewelry, such as combs, brushes, and rings. The bulk of the world's hawksbill sea 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

Dominican Republic

The Dominican Republic is a nation on the island of La Hispaniola, part of the Greater Antilles archipelago in the Caribbean region. The western third of the island is occupied by the nation of Haiti, making Hispaniola one of two Caribbean islands that are shared by two countries...

and Colombia

Colombia

Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...

.

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

Venezuelan bolívar

The bolívar fuerte is the currency of Venezuela since 1 January 2008. It is subdivided into 100 céntimos and replaced the bolívar at the rate of Bs.F. 1 = Bs...

and the 2-Brazilian Reais

Brazilian real

The real is the present-day currency of Brazil. Its sign is R$ and its ISO code is BRL. It is subdivided into 100 centavos ....

banknotes. A much-beloved fountain sculpture of a boy riding a hawksbill, affectionately known as Turtle Boy

Burnside Fountain

The Burnside Fountain, affectionately called Turtle Boy, is a statue of a boy "riding" a hawksbill sea turtle created by sculptor Charles Y. Harvey. The statue stands on a pedestal of pink granite created by architect Henry Bacon, who later designed the Lincoln Memorial in Washington, DC...

, stands in Worcester, Massachusetts

Worcester, Massachusetts

Worcester is a city and the county seat of Worcester County, Massachusetts, United States. Named after Worcester, England, as of the 2010 Census the city's population is 181,045, making it the second largest city in New England after Boston....

Conservation

General consensus has determined sea turtles, including E. 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 accidentally. In addition, human and animal encroachment threatens nesting sites and small mammals dig up eggs. In the U.S. Virgin Islands, mongoose

Mongoose

Mongoose are a family of 33 living species of small carnivorans from southern Eurasia and mainland Africa. Four additional species from Madagascar in the subfamily Galidiinae, which were previously classified in this family, are also referred to as "mongooses" or "mongoose-like"...

s raid Hawksbill nests (along with those of other sea turtles like Dermochelys coriacea) right after they are laid.

In 1982 the IUCN Red List

IUCN Red List

The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...

of Threatened Species first listed E. imbricata as endangered

Endangered species

An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

. This endangered status continued through several reassessments in 1986, 1988, 1990, and 1994 until it was upgraded in status to critically endangered in 1996. Two petitions challenged its status as an endangered species

Endangered species

An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

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 sea 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.

The species (along with the entire family Cheloniidae

Cheloniidae

Cheloniidae is a family of turtles belonging to the sea turtle superfamily Chelonioidea.-Extant genera:*Genus Caretta**Loggerhead sea turtle *Genus Chelonia**Green sea turtle *Genus Eretmochelys...

) has been listed on Appendix I of the Convention on International Trade in Endangered Species. It is illegal to import or export turtle products, or to kill, capture, or harass hawksbill sea turtles.

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

The United States Fish and Wildlife Service

United States Fish and Wildlife Service

The United States Fish and Wildlife Service is a federal government agency within the United States Department of the Interior dedicated to the management of fish, wildlife, and natural habitats...

and National Marine Fisheries Service

National Marine Fisheries Service

The National Marine Fisheries Service is a United States federal agency. A division of the National Oceanic and Atmospheric Administration and the Department of Commerce, NMFS is responsible for the stewardship and management of the nation's living marine resources and their habitat within the...

have classified hawksbills as endangered under the Endangered Species Act since 1970. The U.S. government established several recovery plans for protecting E. imbricata.

External links

US National Marine Fisheries Service hawksbill sea turtle page
Florida Sea Turtle information Florida Fish and Wildlife Conservation Commission Fish and Wildlife Research Institute
WWF-Malaysia's Hawksbill Turtles Satellite Telemetry Website WWF-Malaysia's website featuring the journey of two satellite tracked hawksbill turtles and other information about hawksbill sea turtles in the region of Malacca, Malaysia.
Seaturtle.org Home to sea turtle conservation efforts such as the Marine Turtle Research Group and publisher of the Marine Turtle Newsletter.
Hawksbill Turtle in Bocas Del Toro

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.