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The hawksbill sea turtle (''Eretmochelys imbricata'') is a critically endangered
sea turtle Sea turtles (superfamily Chelonioidea), sometimes called marine turtles, are reptiles of the order Testudines Turtles are reptile Reptiles are tetrapod Tetrapods (; from Greek 'four' and 'foot') are four-limbed animals constitut ...

sea turtle
belonging to the family
Cheloniidae Cheloniidae is a family of typically large marine turtles that are characterised by their common traits such as, having a flat streamlined wide and rounded shell and almost paddle-like flippers for their forelimbs. The six species that make up th ...
. It is the only extant
species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individu ...

species
in the
genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific study of naming, defining (Circumscription (taxonomy), circumscribing) and classifying gr ...
''Eretmochelys''. The species has a worldwide distribution, with
Atlantic
Atlantic
and
Indo-Pacific The Indo-Pacific, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, is a biogeographic Biogeography is the study of the distribution of species In biology, a species is the basic unit of biological classification, class ...
subspecies In biological classification In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interacti ...
—''E. i. imbricata'' and ''E. i. bissa'', respectively. The hawksbill's appearance is similar to that of other marine turtles. In general, it has a flattened body shape, a protective
carapace A carapace is a Dorsum (biology), dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tor ...
, and flipper-like limbs, adapted for swimming in the open ocean. ''E. imbricata'' is easily distinguished from other sea turtles by its sharp, curving
beak The beak, bill, and/or rostrum is an external anatomical structure found mostly in birds Birds are a group of warm-blooded vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellu ...

beak
with prominent
tomium In anatomy, the tomium is the sharp cutting edge of the beak of a bird or the bill of a turtle. Sometimes the edge is serrated for tearing through flesh or vegetation. See also * Culmen (bird) * Gonys References

Vertebrate anatomy {{Verte ...
, 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 A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' and ''atoll lagoons''. They ...

lagoon
s and
coral reef A coral reef is an underwater ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient c ...

coral reef
s. The
World Conservation Union The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization An international organization (also known as an international institut ...
, primarily as a result of human fishing practices, classifies ''E. imbricata'' as critically endangered. Hawksbill shells were the primary source of
tortoiseshell material Tortoiseshell or tortoise shell is a material produced from the shells of the larger species of tortoise Tortoises () are reptiles Reptiles are tetrapod Tetrapods (; from Greek 'four' and 'foot') are four-limbed animals constitutin ...
used for decorative purposes. The
Convention on International Trade in Endangered Species CITES (shorter name for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty A multilateral treaty is a treaty A treaty is a formal, leg ...
outlaws the capture and trade of hawksbill sea turtles and products derived from them.


Anatomy and morphology

Adult hawksbill sea turtles typically grow to in length, weighing around on average. The heaviest hawksbill ever captured weighed . 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. Several characteristics of the hawksbill sea turtle 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 forelimbs have two visible claws on each flipper. One of the hawksbill's more easily distinguished characteristics is the pattern of thick
scute A scute or scutum (Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the ...
s that make up its carapace. While its carapace has five central scutes and four pairs of
lateral Lateral is a geometric term of location which may refer to: Healthcare *Lateral (anatomy), an anatomical direction *Lateral cricoarytenoid muscle *Lateral release (surgery), a surgical procedure on the side of a kneecap Phonetics *Lateral cons ...
scutes like several members of its family, ''E. imbricata'' posterior scutes overlap in such a way as to give the rear margin of its carapace a
serrated Serration is a saw-like appearance or a row of sharp or tooth-like projections. A serrated cutting edge has many small points of contact with the material being cut. By having less contact area than a smooth blade or other edge, the applied pre ...
look, similar to the edge of a
saw A saw is a tool A tool is an object that can extend an individual's ability to modify features of the surrounding environment. Although many animals use simple tools, only human beings, whose use of stone tool A stone tool is, in the ...

saw
or a steak knife. The turtle's carapace can reach almost in length. The hawksbill appears to frequently employ its sturdy shell to insert its body into tight spaces in reefs. Crawling with an alternating
gait Gait is the pattern of movement Movement may refer to: Common uses * Movement (clockwork), the internal mechanism of a timepiece * Motion (physics), commonly referred to as movement Arts, entertainment, and media Literature * Movemen ...
, hawksbill tracks left in the sand are asymmetrical. In contrast, the
green sea turtle The green sea turtle (''Chelonia mydas''), also known as the green turtle, black (sea) turtle or Pacific green turtle, is a species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank ...

green sea turtle
and the
leatherback turtle The leatherback sea turtle (''Dermochelys coriacea''), sometimes called the lute turtle or leathery turtle or simply the luth, is the largest of all living turtle Turtles are an of s known as Testudines, characterized by a developed ma ...
have a more symmetrical gait. Due to its consumption of venomous
cnidaria Cnidaria () is a phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the values of the grammatical number, grammatical category of number. The plural of ...

cnidaria
ns, hawksbill sea turtle flesh can become
toxic Toxicity is the degree to which a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects t ...

toxic
. The hawksbill is
biofluorescent Fluorescence is the emission of light Light or visible light is electromagnetic radiation within the portion of the electromagnetic spectrum that is visual perception, perceived by the human eye. Visible light is usually defined as ha ...
and is the first reptile recorded with this characteristic. It is unknown if the effect is due to the turtle's diet, which includes biofluorescent organisms like the hard coral '' Physogyra lichtensteini''. Males have more intense pigmentation than females, and a behavioural role of these differences is speculated. Tortue imbriqueeld4.jpg, Carapace's serrated margin and overlapping
scute A scute or scutum (Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the ...
s are evident in this individual, alt=Photo from above of swimming turtle, with four outstretched flippers and faceted shell Hawksbill turtle doeppne-081.jpg, Close-up of the hawksbill's distinctive beak, alt=Profile photo of animal head with prominent beak protruding above lower jaw, a faceted head covering surrounds the eye Fluorescent Turtle.jpg, Fluorescent markings on Hawksbill sea turtle


Distribution

Hawksbill sea turtles have a wide
range Range may refer to: Geography * Range (geographic), a chain of hills or mountains; a somewhat linear, complex mountainous or hilly area (cordillera, sierra) ** Mountain range, a group of mountains bordered by lowlands * Range, a term used to i ...
, found predominantly in tropical reefs of the
Indian Indian or Indians refers to people or things related to India, or to the indigenous people of the Americas, or Aboriginal Australians until the 19th century. Peoples South Asia * Indian people, people of Indian nationality, or people who hav ...

Indian
,
Pacific The Pacific Ocean is the largest and deepest of Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of continents and islands. ...

Pacific
, and Oceans. Of all the sea turtle species, ''E. imbricata'' is the one most associated with warm tropical waters. Two significant
subpopulation In statistics Statistics is the discipline that concerns the collection, organization, analysis, interpretation, and presentation of data. In applying statistics to a scientific, industrial, or social problem, it is conventional to begin with ...
s are known, in the Atlantic and Indo-Pacific.


Atlantic subpopulation

In the Atlantic, hawksbill populations range as far west as the
Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an ocean basin 400px, Diagrammatic cross-section of an ocean basin, showing the various geographic features In hydrology Hydrology (from Greek: wikt:ὕδωρ, ὕδωρ, "hýdōr" meaning ...

Gulf of Mexico
and as far southeast as the
Cape of Good Hope A cape is a sleeveless outer garment, which drapes the wearer's back, arms, and chest, and connects at the neck. History Capes were common in medieval Europe, especially when combined with a Hood (headgear), hood in the Chaperon (headgear), ...

Cape of Good Hope
in
South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. With over 60 million people, it is the world's 23rd-most populous nation and covers an area of . South Africa has three capital citie ...

South Africa
. They live off the
Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At 8.5 million square kilometers (3.2 million square miles) and with over 211 mill ...

Brazil
ian coast (specifically
Bahia Bahia (; ) ("bay" in Portuguese Portuguese may refer to: * anything of, from, or related to the country and nation of Portugal ** Portuguese cuisine, traditional foods ** Portuguese language, a Romance language *** Portuguese dialects, variants ...

Bahia
,
Fernando de Noronha Fernando de Noronha () is an archipelago in the Atlantic Ocean, part of the Pernambuco, State of Pernambuco, Brazil, and located offshore from the Brazilian coast. It consists of 21 islands and islets, extending over an area of . Only the eponymo ...

Fernando de Noronha
) through southern
Florida Florida is a U.S. state, state located in the Southeastern United States, Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia (U.S. state), Geor ...

Florida
and
Virginia Virginia (), officially the Commonwealth of Virginia, is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), '' ...

Virginia
waters. In the
Caribbean The Caribbean (, ; es, Caribe; french: Caraïbes; ht, Karayib; also gcf, label=Antillean Creole Antillean Creole (Antillean French Creole, Kreyol, Kwéyòl, Patois) is a French-based creole, which is primarily spoken in the Lesser Antilles ...
, the main nesting beaches are in the
Lesser Antilles The Lesser Antilles ( es, link=no, Antillas Menores; french: link=no, Petites Antilles; pap, Antias Menor; nl, Kleine Antillen) are a group of islands in the Caribbean Sea The Caribbean Sea ( es, Mar Caribe; french: Mer des Caraïbes; ht, ...
,
Barbados Barbados is an island country An island country or an island nation is a country A country is a distinct territory, territorial body or political entity. It is often referred to as the land of an individual's birth, residence or c ...

Barbados
, Guadeloupe, Tortuguero in
Costa Rica Costa Rica (, ; ; literally "Rich Coast"), officially the Republic of Costa Rica ( es, República de Costa Rica), is a country in Central America Central America ( es, América Central, , ''Centroamérica'' ) is a region of the Amer ...

Costa Rica
, and the . They feed in the waters off
Cuba Cuba ( , ), officially the Republic of Cuba ( es, República de Cuba, links=no ), is a country comprising the island of Cuba, as well as Isla de la Juventud Isla de la Juventud (; en, Isle of Youth) is the second-largest Cuban islan ...

Cuba
and around
Mona Island Mona ( es, Isla de Mona) is the third-largest island of the Puerto Rican archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster or collection of island An island (or isle) is an ...
near
Puerto Rico Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico) is a Caribbean island and Unincorporated ...

Puerto Rico
, among other places.


Indo-Pacific subpopulation

In the
Indian Ocean The Indian Ocean is the third-largest of the world's five ocean The ocean (also the or the world ocean) is the body of that covers approximately 70.8% of the surface of and contains 97% of . Another definition is "any of the large ...

Indian Ocean
, hawksbills are a common sight along the east coast of Africa, including the seas surrounding
Madagascar Madagascar (; mg, Madagasikara), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), and previously known as the Malagasy Republic The Malagasy Republic ( mg, Repoblika Mal ...

Madagascar
and nearby island groups. Hawksbills are also common along the southern Asian coast, including the
Persian Gulf The Persian Gulf ( fa, خلیج فارس, translit=xalij-e fârs, lit=Gulf of , ) is a in . The body of water is an extension of the () through the and lies between to the northeast and the to the southwest.United Nations Group of Exper ...
, the
Red Sea The Red Sea ( ar, البحر الأحمر, translit=al-Baḥr al-ʾAḥmar; or ; Coptic Coptic may refer to: Afro-Asia * Copts, an ethnoreligious group mainly in the area of modern Egypt but also in Sudan and Libya * Coptic language, a North ...

Red Sea
, and the Indian subcontinent and
Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia or SEA, is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern subregion of Asia, consisting of the regions ...

Southeast Asia
coasts. They are present across the
Malay Archipelago The Malay Archipelago ( ceb, Kapupud-ang Malay, ms, Kepulauan Melayu, tgl, Kapuluang Malay, jv, Nusantara) is the archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster or collection o ...

Malay Archipelago
and northern
Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

Australia
. Their
Pacific The Pacific Ocean is the largest and deepest of Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of continents and islands. ...

Pacific
range is limited to the ocean's tropical and subtropical regions. In the west, it extends from the southwestern tips of the
Korean Peninsula Korea is a region In geography, regions are areas that are broadly divided by physical characteristics (physical geography), human impact characteristics (human geography), and the interaction of humanity and the environment (environmental ...

Korean Peninsula
and the
Japanese Archipelago The Japanese archipelago (Japanese: 日本列島, ''Nihon rettō'') is a group of 6,852 islands that form the country of Japan Japan ( ja, 日本, or , and formally ) is an island country An island country or an island nation is a ...
south to northern
New Zealand New Zealand ( mi, Aotearoa ''Aotearoa'' (; commonly pronounced by English English usually refers to: * English language English is a West Germanic languages, West Germanic language first spoken in History of Anglo-Saxon Engl ...

New Zealand
. The
Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

Philippines
hosts several nesting sites, including the island of
Boracay Boracay () is a small island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atoll An atoll (), som ...

Boracay
and Punta Dumalag in
Davao City , officially the ( ceb, Dakbayan sa Dabaw; tl, Lungsod ng Davao), is a in the , . The city has a total land area of , making it the largest city in the Philippines in terms of land area. It is the third-most populous city in the Philipp ...
. Dahican Beach in Mati City,
Davao Oriental Davao Oriental (Cebuano language, Cebuano: ''Sidlakang Dabaw''; tl, Silangang Davao) is a Provinces of the Philippines, province in the Philippines located in the Davao Region in Mindanao. Its capital is Mati, Davao Oriental, Mati, and it borders ...
, hosts one of the essential hatcheries of its kind, along with
olive ridley sea turtle The olive ridley sea turtle (''Lepidochelys olivacea''), also known commonly as the Pacific ridley sea turtle, is a species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an or ...

olive ridley sea turtle
s in the archipelagic country of the Philippines. A small group of islands in the southwest of the
archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster or collection of island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as ...

archipelago
is named the " Turtle Islands" because two species of sea turtles nest there: the hawksbill and the green sea turtle. In January 2016, a juvenile was seen in
Gulf of Thailand The Gulf of Thailand, also known as the Gulf of Siam, is a shallow inlet in the southwestern South China Sea The South China Sea is a of the . It is bounded in the north by the shores of (hence the name), in the west by the , in the east ...

Gulf of Thailand
. A 2018 article by
The Straits Times ''The Straits Times'' is an English-language daily broadsheet newspaper based in Singapore and currently owned by Singapore Press Holdings. ''The Sunday Times'' is its Sunday edition. The newspaper was established on 15 July 1845 as ''The Stra ...
reported that around 120 hawksbill juvenile turtles recently hatched at
Pulau Satumu Pulau Satumu (Chinese language, Chinese: 沙都姆岛) is a small island to the south of the main Singapore island, and the southernmost island of Singapore. The Raffles Lighthouse is located on the island. The island's name means "One Tree" in a ...
,
Singapore Singapore (), officially the Republic of Singapore, is a sovereign state, sovereign island city-state in maritime Southeast Asia. It lies about one degree of latitude () north of the equator, off the southern tip of the Malay Peninsula, bor ...

Singapore
. Commonly found in Singapore waters, hawksbill turtles have returned to areas such
East Coast Park East Coast Park is a beach and a park encompassing Marine Parade, Bedok and Tampines, along the southeastern coast of Singapore. It was opened in the 1970s, after the Government of Singapore, Singapore government had completed reclaiming land o ...

East Coast Park
and Palau Satumu to nest. In Hawaii, hawksbills mostly nest on the "main" islands of
Oahu Oahu () (Hawaiian Hawaiian may refer to: * Hawaii state residents, regardless of ancestry * Native Hawaiians, the current term for the indigenous people of the Hawaiian Islands or their descendants * Hawaiian language Historic uses * things ...

Oahu
,
Maui The island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atoll An atoll (), sometimes known as ...

Maui
,
Molokai Molokai , or Molokai (), is the fifth most populated of the eight major islands that make up the Hawaiian Islands archipelago in the middle of the Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divis ...

Molokai
, and
Hawaii Hawaii ( ; haw, Hawaii or ) is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspape ...
. In
Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

Australia
, hawksbills are known to nest on Milman Island in the
Great Barrier Reef The Great Barrier Reef is the world's largest coral reef A coral reef is an underwater ecosystems, ecosystem characterized by reef-building corals. Reefs are formed of Colony (biology), colonies of coral polyp (zoology), polyps held tog ...

Great Barrier Reef
. Hawksbill sea turtles nest as far west as
Cousine Island Cousine Island is a small granitic island in the Seychelles west of Praslin Island. It is a combination luxury resort and since 1992 a nature preserve. History In 1992 the island was purchased and a conservation program was introduced to protec ...
in the
Seychelles Seychelles (; ), officially the Republic of Seychelles (french: link=no, République des Seychelles; Creole: ''La Repiblik Sesel''), is an archipelagic island country An island country or an island nation is a country A country ...

Seychelles
, where the species since 1994 is legally protected, and the population is showing some recovery. The Seychelles' inner islands and islets, such as
Aldabra Aldabra is the world's second-largest coral atoll. It is situated in the Aldabra Group of islands in the Indian Ocean that are part of the Outer Islands (Seychelles), Outer Islands of the Seychelles, with a distance of 1,120 km (700 m ...
, are popular feeding grounds for immature hawksbills.


Eastern Pacific subpopulation

In the eastern Pacific, hawksbills are known to occur from the
Baja Peninsula The Baja California Peninsula ( en, Lower California Peninsula, es, Península de Baja California) is a peninsula in Northwestern Mexico. It separates the Pacific Ocean from the Gulf of California. The peninsula extends from Mexicali, Baja Ca ...
in
Mexico Mexico, officially the United Mexican States, is a country A country is a distinct territorial body or political entity A polity is an identifiable political entity—any group of people who have a collective identity, who are organi ...

Mexico
south along the coast to southern
Peru , , image_flag = Flag_of_Peru.svg , image_coat = Escudo_nacional_del_Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (device), National seal , national_mott ...

Peru
. Nonetheless, as recently as 2007, the species had been considered extirpated mainly in the region. Important remnant nesting and foraging sites have since been discovered in Mexico,
El Salvador , national_anthem = '' Himno Nacional de El Salvador''( en, "National Anthem of El Salvador") , image_map = El Salvador (orthographic projection).svg , image_map2 = , capital = San Salvador , coordinates = , largest_city = San Salvador ...

El Salvador
,
Nicaragua Nicaragua (; ), officially the Republic of Nicaragua (), is the largest Sovereign state, country in the Central American isthmus, bordered by Honduras to the northwest, the Caribbean Sea, Caribbean to the east, Costa Rica to the south, and th ...

Nicaragua
, and
Ecuador Ecuador ( ; ; Quechua Quechua may refer to: *Quechua people, several indigenous ethnic groups in South America, especially in Peru *Quechuan languages, a Native South American language family spoken primarily in the Andes, derived from a ...

Ecuador
, providing new research and conservation opportunities. 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 The Gulf of Fonseca ( es, Golfo de Fonseca; ), a part of the Pacific Ocean The Pacific Ocean is the largest and deepest of Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and s ...
(Nicaragua, El Salvador, and Honduras), Estero Padre Ramos (Nicaragua), and the
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 Santa Elena, Ecuador, Santa Elena, in Ecuador, and its southern limit is Cabo Blanco, Peru, Cabo Blanco, in Peru. The g ...
(Ecuador). Multi-national initiatives, such as th
Eastern Pacific Hawksbill Initiative
are currently pushing efforts to research and conserve the population, which remains poorly understood.


Habitat and feeding


Habitat

Adult hawksbill sea turtles are primarily found in tropical
coral reef A coral reef is an underwater ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient c ...

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 lagoons and even mangrove swamps in estuaries. Little is known about the habitat preferences of early life-stage ''E. imbricata''; like other young sea turtles, they are assumed to be completely pelagic, remaining at sea until they mature.


Feeding

While they are omnivorous,
sea sponge Sponges, the members of the phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the values of the grammatical number, grammatical category of number. T ...

sea sponge
s are their principal food; they constitute 70–95% of the turtles' diets. However, like many
spongivore A spongivore is an animal Animals (also called Metazoa) are multicellular A multicellular organism is an organism In biology, an organism () is any organic, life, living system that functions as an individual entity. All organ ...
s, they feed only on select species, ignoring many others. Caribbean populations feed primarily on the orders
Astrophorida Astrophorina is a Order (biology), suborder of sea sponges in the class Demospongiae. Astrophorina was formerly named Astrophorida and classified as an order, but it is now recognised as a suborder of TetractinellidaMorrow & Cárdenas' (2015) rev ...
, Spirophorida, and
Hadromerida Heteroscleromorpha is a Subclass (biology), subclass of demosponges within the phylum Sponge, Porifera.van Soest, R. (2016)Heteroscleromorpha.Accessed through: World Register of Marine Species on 2017-02-17. References

Heteroscleromorpha ...
in the class
Demospongiae Demosponges (Class Demospongiae) are the most diverse class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or o ...
. Aside from sponges, hawksbills feed on
algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic Photosynthesis is a process used by plants and other organisms to convert Conversion or convert may refer to: Arts, entertainment, and media * Co ...

algae
, marine plants,
cnidaria Cnidaria () is a phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the values of the grammatical number, grammatical category of number. The plural of ...

cnidaria
ns,
comb jellies Ctenophora (; ctenophore ; ) comprise a phylum of marine life, marine invertebrates, commonly known as comb jellies, that marine habitats, inhabit sea waters worldwide. They are notable for the groups of cilia they use for swimming (commonly ...

comb jellies
and other
jellyfish Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum In zoological nomenclature The International Code of Zoological Nomenclature (ICZN) is a widely accepted Con ...

jellyfish
,
sea anemone Sea anemones are the marine, predatory Predation is a biological interaction In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms ...

sea anemone
s,
mollusks Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda. The members are known as molluscs or mollusks (). Around 85,000 extant taxon, extant species of molluscs are recognized. The number of fossil species is e ...
,
fish Fish are aquatic Aquatic means relating to water Water (chemical formula H2O) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the ...

fish
and
crustaceans Crustaceans (Crustacea ) form a large, diverse arthropod An arthropod (, (gen. ποδός)) is an invertebrate Invertebrates are animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), de ...
. They also feed on the dangerous jellyfish-like
hydrozoa Hydrozoa (hydrozoans; ) are a taxonomic Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also refer to a specific classification sch ...

hydrozoa
n, the
Portuguese man o' war The Portuguese man o' war (''Physalia physalis''), also known as the man-of-war, bluebottle, or blue bottle jellyfish, is a marine hydrozoa Hydrozoa (hydrozoans; ) are a taxonomic Taxonomy (general) is the practice and science of classificat ...

Portuguese man o' war
(''Physalia physalis''). Hawksbills close their unprotected eyes when they feed on these cnidarians. The man o' war's cannot penetrate the turtles' armored heads. Hawksbills are highly resilient and resistant to their prey. Some of the sponges they eat, 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 with significant numbers of siliceous spicule (sponge), spicules, such as ''Ancorina'', ''Geodia'' (''Geodia gibberosa, G. gibberosa''), ''Ecionemia'', and ''Placospongia''.


Life history

Not much is known about the life history of hawksbills. Their life history can be divided into three phases: namely the pelagic or aquatic phase, from hatching to about 20 cm, the benthic phase, when the immature turtles recruit to foraging areas, and the reproductive phase, when they reach sexual maturity. The pelagic phase possibly lasts until the turtles reach around 20 cm in length in 1–3 years, reaching sexual maturity at around 40 cm (2–4 years). Hawksbills show a degree of fidelity after recruiting to the benthic phase however, the movement to other similar habitats is possible.


Breeding

Hawksbills mate biannually in secluded lagoons off their nesting beaches in remote islands throughout their range. The most significant nesting beaches are in Mexico, the Seychelles, Indonesia, Sri Lanka, and Australia. The mating season for Atlantic hawksbills usually spans April to November. Indian Ocean populations, such as the
Seychelles Seychelles (; ), officially the Republic of Seychelles (french: link=no, République des Seychelles; Creole: ''La Repiblik Sesel''), is an archipelagic island country An island country or an island nation is a country A country ...

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, then lay Clutch (eggs), clutches of eggs and cover them with sand.
Caribbean The Caribbean (, ; es, Caribe; french: Caraïbes; ht, Karayib; also gcf, label=Antillean Creole Antillean Creole (Antillean French Creole, Kreyol, Kwéyòl, Patois) is a French-based creole, which is primarily spoken in the Lesser Antilles ...
and
Florida Florida is a U.S. state, state located in the Southeastern United States, Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia (U.S. state), Geor ...

Florida
nests of ''E. imbricata'' typically contain around 140 eggs. After the hours-long process, the female returns to the sea. Their nests can be found throughout beaches in about 60 countries. Hatchlings, usually weighing less than , hatch at night after around two months. These newly emergent hatchlings are dark-colored, with heart-shaped carapaces measuring approximately long. They instinctively crawl into the sea, attracted by the moon's reflection on the water (disrupted by light sources such as street lamps and lights). While they emerge under the cover of darkness, hatchlings that do not reach the water by daybreak are preyed upon by shorebirds, Grapsidae, shore crabs, and other predators.


Maturity

Hawksbills evidently reach maturity after 20 years. Their lifespan is unknown. Like other sea turtles, hawksbills are solitary for most of their lives; they meet only to mate. They are highly Animal migration, migratory. Because of their tough carapace#Turtles and tortoises, carapaces, adults' only predators are sharks, Saltwater crocodile, estuarine crocodiles, octopuses, and some pelagic fish species. 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, all marine turtles of the same aggregation are highly unlikely to reach sexual maturity at the same size and thus age. Age at maturity has been estimated to occur between 10 and 25 years of age 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 spongivore, spongivorous reptile. Because of this, its evolutionary position is somewhat unclear. Molecular analyses support ''Eretmochelys'' placement within the Tribe (biology), taxonomic tribe Loggerhead sea turtle, Carettini, including the carnivorous loggerhead turtle, loggerhead and ridley sea turtles, rather than in the tribe Green sea turtle, 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, in the 12th edition of Systema Naturae, 12th edition of his ''Systema Naturae''. In 1843, Austrian zoologist Leopold Fitzinger moved it into the genus ''Eretmochelys''. In 1857, the species was temporarily misdescribed as ''Eretmochelys imbricata squamata''. Two
subspecies In biological classification In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interacti ...
are accepted in ''E. imbricata's'' taxon. ''E. i. bissa'' (Eduard Rüppell, Rüppell, 1835) refers to populations that reside in the Pacific Ocean. The population is a separate subspecies, ''E. i. imbricata'' (Carl Linnaeus, Linnaeus, 1766). The nominate subspecies is the Atlantic taxon because Linnaeus' Type (biology), type specimen was from the Atlantic. Leopold Fitzinger, Fitzinger derived the genus name ''Eretmochelys'' from the Greek language, 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 language, Latin, corresponding to the English term wikt:imbricate, 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 sea turtle.


Exploitation by humans

Throughout the world, hawksbill sea turtles are taken by humans, 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 BC, sea turtles, including the hawksbill, were eaten as delicacies in China. Many cultures also use turtle shells for decoration. These turtles have been harvested for their beautiful shell since Egyptian times, and the material known as tortoiseshell is normally from the hawksbill. STRP Hawksbill Sea Turtle 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 to make and decorate a variety of small items, as it was in the West. Along the south coast of Java, stuffed hawksbill turtles are sold in souvenir shops, though numbers have decreased in the last two decades. In Japan, the turtles are also harvested for their shell
scute A scute or scutum (Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the ...
s, called ''bekko'' in Japanese language, Japanese. It is used in various personal implements, such as eyeglass frames and the ''shamisen'' (Japanese traditional three-stringed instrument) picks. In 1994, Japan stopped importing hawksbill shells from other nations. Prior to this, the Japanese hawksbill shell trade was around of raw shells per year. In the West, hawksbill sea turtle shells were harvested by the ancient Greeks and ancient Romans for jewellery, such as combs, brushes, and rings. The bulk of the world's hawksbill shell trade originates in the Caribbean. In 2006, processed shells were regularly available in large amounts in countries including the Dominican Republic and Colombia. The hawksbill sea turtle appears on the reverse side of the Venezuelan 20-Venezuelan bolívar, bolivar and the Brazilian 2-Brazilian real, reais banknotes. A much-beloved fountain sculpture of a boy riding a hawksbill, affectionately known as ''Burnside Fountain, Turtle Boy'', stands in Worcester, Massachusetts, Worcester, Massachusetts.


Conservation

Consensus has determined sea turtles, including ''E. imbricata'' to be, at the very least, threatened species because of their slow growth and maturity and slow reproductive rates. Humans have killed many adult turtles, both accidentally and deliberately. Their existence is threatened due to pollution and loss of nesting areas because of coastal development. Biologists estimate that the hawksbill population has declined 80 percent in the past 100–135 years. Human and animal encroachment threatens nesting sites, and small mammals dig up the eggs to eat. In the US Virgin Islands, mongooses raid hawksbill nests (along with other sea turtles, such as ''Leatherback sea turtle, Dermochelys coriacea'') right after they are laid. In 1982, the IUCN Red List of Threatened Species first listed ''E. imbricata'' as endangered species, endangered. This endangered status continued through several reassessments in 1986, 1988, 1990, and 1994 until it was upgraded in status to ''Critically endangered species, critically endangered'' in 1996. Two petitions challenged its status as an endangered species prior to this, claiming the turtle (along with three other species) had several significant stable populations worldwide. These petitions were rejected based on their data analysis submitted by the Marine Turtle Specialist Group (MTSG). The data given by the MTSG showed the worldwide hawksbill sea turtle population had declined by 80% in the three most recent generations, and no significant population increase occurred 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) has been listed in Appendix I of the
Convention on International Trade in Endangered Species CITES (shorter name for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty A multilateral treaty is a treaty A treaty is a formal, leg ...
. It is prohibited to import or export turtle products, or kill, capture, or harass hawksbill sea turtles. The United States Fish and Wildlife Service and National Marine Fisheries Service have classified hawksbills as endangered under the Endangered Species Act since 1970. The US government established several recovery plans for protecting ''E. imbricata''. The Zoological Society of London has inscribed the reptile as an EDGE species, meaning that it is both endangered and highly genetically distinct, and therefore of particular concern for conservation efforts. Local involvement in conservation efforts has also increased in the past few years. The World Wildlife Fund Australia (WWF-Australia) has several ongoing projects aiming at protecting the reptile. On Rosemary Island, an island in the Dampier Archipelago off the Pilbara coast of Western Australia, volunteers have been monitoring hawksbill turtles since 1986. In November 2020, a 60-year old turtle first tagged in November 1990 and again in 2011 returned to the same location.


References


External links

*
US National Marine Fisheries Service hawksbill sea turtle page

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

Australian Government Department of the Environment
* {{DEFAULTSORT:turtle, sea, hawksbill Eretmochelys, hawksbill sea turtle Sea turtles, hawksbill sea-turtle Pantropical fauna Critically endangered animals ESA endangered species Reptiles described in 1766, hawksbill sea turtle Taxa named by Carl Linnaeus