Thegreen sea turtle (Chelonia mydas), also known as thegreen turtle,black sea turtle, andPacific green turtle,[5] is aspecies of largesea turtle of thefamilyCheloniidae. It is the onlyspecies in thegenusChelonia.[6] Its range extends throughouttropical andsubtropical seas around the world, with two distinct populations in theAtlantic andPacific Oceans, but it is also found in theIndian Ocean.[7][8] The common name refers to the usually greenfat found beneath itscarapace, due to its diet strictly being seagrass,[9] not to the color of its carapace, which is olive to black.
Thedorsoventrally flattened body ofC. mydas is covered by a large, teardrop-shaped carapace; it has a pair of large,paddle-likeflippers. It is usually lightly colored, although in the eastern Pacific populations, parts of the carapace can be almost black. Unlike other members of its family, such as thehawksbill sea turtle,C. mydas is mostlyherbivorous. The adults usually inhabit shallowlagoons, feeding mostly on various species ofseagrasses.[10] The green sea turtle is the only aquatic turtle species which is herbivorous when fully grown.
Like other sea turtles, green sea turtlesmigrate long distances between feeding grounds and hatching beaches. Many islands worldwide are known asTurtle Island due to green sea turtles nesting on their beaches. Females crawl out on beaches, dig nests, and lay eggs during the night. Later, hatchlings emerge, and scramble into the water. Those that reachmaturity may live to 90 years in the wild.[7]
C. mydas was listed asendangered by theIUCN andCITES until 2025 and is protected from exploitation in most countries.[11] It is illegal to collect, harm, or kill them. In addition, many countries have laws and ordinances to protect nesting areas. However, turtles are still in danger due to human activity. In some countries, turtles and their eggs are stillhunted for food.Pollution indirectly harms turtles at both population and individual scales. Many turtles die after beingcaught in fishing nets. In addition, real estatedevelopment often causeshabitat loss by eliminating nesting beaches.
The green sea turtle is a member of thetribeCheloniini.[12] A 1993 study clarified the status ofgenusChelonia with respect to the other marine turtles. ThecarnivorousEretmochelys (hawksbill),Caretta (loggerhead) andLepidochelys (ridley) were assigned to the tribeCarettini.HerbivorousChelonia warranted their status as agenus, whileNatator (flatback) was further removed from the other genera than previously believed.[13]
The species was originally described byCarl Linnaeus in his landmark 175810th edition ofSystema Naturae asTestudo mydas.[14] In 1868,Marie Firmin Bocourt named a particular species of sea turtleChelonia agassizii,[15][16] in honor of Swiss-American zoologistLouis Agassiz.[17] This "species" was referred to as the "black sea turtle".[18] Later research determined Bocourt's "black sea turtle" was not genetically distinct fromC. mydas, and thustaxonomically not a separate species.[19] These two "species" were then united asChelonia mydas and populations were given subspecies status:C. mydas mydas referred to the originally described population, whileC. mydas agassizi referred only to the Pacific population known as the Galápagos green turtle.[20][21] This subdivision was later determined to be invalid and all species members were then designatedChelonia mydas.[6] The oft-mentioned nameC. agassizi remains an invalidjunior synonym ofC. mydas.
The species'common name does not derive from any particulargreen external coloration of the turtle. Its name comes from the greenish color of the turtles' fat, which is only found in a layer between their inner organs and their shell.[22] As a species found worldwide, the green turtle has many local names. In theHawaiian language it is calledhonu,[23][24] and it is locally known as a symbol of good luck and longevity.[25]
Green sea turtle swimming over the sand plateau at playa Grandi,Curaçao
Its appearance is that of a typicalsea turtle.C. mydas has a dorsoventrally flattened body, a beaked head at the end of a short neck, and paddle-like arms well-adapted for swimming.[26] Adult green turtles grow to 1.5 metres (5 ft) long.[27] The average weight of mature individuals is 68–190 kg (150–419 lb) and the average carapace length is 78–112 cm (31–44 in).[28] They are considered the second largest sea turtle in the United States, after the leatherback sea turtle.[29]Exceptional specimens can weigh 315 kg (694 lb) or even more, with the largest knownC. mydas having weighed 395 kg (871 lb) and measured 153 cm (60 in) in carapace length.[30]
Anatomically, a few characteristics distinguish the green turtle from the other members of its family. Unlike its close relative thehawksbill turtle, the green turtle's snout is very short and itsbeak is unhooked. The neck cannot be pulled into the shell.[31] The sheath of the turtle's upper jaw possesses a denticulated edge, while its lower jaw has stronger, serrated, more defined denticulation. The dorsal surface of the turtle's head has a single pair of prefrontal scales. Its carapace is composed of five centralscutes flanked by four pairs of lateral scutes. Underneath, the green turtle has four pairs of inframarginal scutes covering the area between the turtle'splastron and its shell. MatureC. mydas front appendages have only a single claw (as opposed to the hawksbill two), although a second claw is sometimes prominent in young specimens.[32]
Thecarapace of the turtle has various color patterns that change over time. Hatchlings ofChelonia mydas, like those of other marine turtles, have mostly black carapaces and light-colored plastrons. Carapaces of juveniles turn dark brown to olive, while those of mature adults are either entirely brown, spotted or marbled with variegated rays. Underneath, the turtle's plastron is hued yellow.C. mydas limbs are dark-colored and lined with yellow, and are usually marked with a large dark brown spot in the center of each appendage.[7][33]
Therange of the green sea turtle extends throughouttropical andsubtropical oceans worldwide. The two majorsubpopulations are the Atlantic and the eastern Pacific subpopulations. Each population is genetically distinct, with its own set of nesting and feeding grounds within the population's known range.[7] One of the genetic differences between the two subpopulations is the type of mitochondrial DNA found in individual's cells. Individuals from rookeries in the Atlantic Ocean and Mediterranean Sea have a similar type of mitochondrial DNA, and individuals from the Pacific and Indian Oceans have another type of mitochondrial DNA.[34] Their native range includes tropical to subtropical waters along continental coasts and islands between 30°N and 30°S. Since green sea turtles are a migrating species, their global distribution spans into the open ocean. The differences in mitochondrial DNA more than likely stems from the populations being isolated from each other by the southern tips of both South America and Africa with no warm waters for the green sea turtles to migrate through. The green sea turtle is estimated to inhabit coastal areas of more than 140 countries, with nesting sites in over 80 countries worldwide throughout the year. In the United States Atlantic coast, green sea turtles can be found fromTexas toMassachusetts. In the United States Pacific coast, they have been found from southernCalifornia north to the southernmost tip of Alaska. The largest populations of green sea turtles within the United States coastline are in theHawaiian Islands andFlorida. Globally, the largest populations of sea turtles are in theGreat Barrier Reef in Australia, and theCaribbean Sea.[35] Recently these Turtles were discovered withinRangaunu Harbour inNew Zealand.[36]
The green sea turtle can generally be found throughout theAtlantic Ocean. Although the species is most abundant in tropical climates, green sea turtles can also be found intemperate climates, and individuals have been spotted as far north asCanada in the western Atlantic, and theCimbrian peninsula in the east. The subpopulation's southern range is known until past the southern tip of Africa in the east andArgentina in the western Atlantic. The major nesting sites can be found on various islands in theCaribbean, along the Atlantic coast ofFlorida in the United States, the eastern coast of theSouth American continent and most notably, on isolatedNorth Atlantic islands.
In the Caribbean, major nesting sites have been identified onAves Island, theU.S. Virgin Islands,Puerto Rico, theDominican Republic, andCosta Rica. In recent years, there are signs of increased nesting in the Cayman Islands.[37] One of the region's most important nesting grounds is inTortuguero in Costa Rica.[38] In fact, the majority of the Caribbean region'sC. mydas population hails from a few beaches in Tortuguero.[39] Within United States waters, minor nesting sites have been noted in the states ofGeorgia,North Carolina, andSouth Carolina.Florida's east coast is the largest nesting site in the United States.Hutchinson Island in particular is a major nesting area in Florida waters. Florida has several annual nesting periods when local beaches are closed or cordoned off to protect nesting sites. According to Green Sea Turtle Watch, in 2015 more than 37,000 green sea turtle nests were documented in Florida, a record number. In addition to sporadic distribution of nesting sites, feeding grounds are much more widely distributed throughoutFlorida. Important feeding grounds inFlorida includeIndian River Lagoon, theFlorida Keys,Florida Bay,Homosassa,Crystal River, andCedar Key.[26][40]
Notable locations in South America include secluded beaches inSuriname andFrench Guiana.[41] In the Southern Atlantic Ocean, the most notable nesting grounds forChelonia mydas are found on the island ofAscension,[26] hosts 6,000–13,000 turtle nests.[42][43][44]
In thePacific, its range reaches as far north as the southern coast ofAlaska and as far south asChile in the east. The turtle's distribution in the western Pacific reaches north toJapan and southern parts ofRussia's Pacific coast, and as far south as the northern tip ofNew Zealand and a few islands south ofTasmania. Significant nesting grounds are scattered throughout the entire Pacific region, includingMexico, theHawaiian Islands, theSouth Pacific, the northern coast ofAustralia, andSoutheast Asia. Major Indian Ocean nesting colonies includeIndia,Pakistan,Sri Lanka and other coastal countries.[45]
The turtles can also be found throughout theIndian Ocean; the east coast of theAfrican continent hosts a few nesting grounds, including islands in the waters aroundMadagascar.[45]
Photo of swimming turtle at twilight in a coral reef nearMexico
Nesting grounds are found all along the Mexican coast. These turtles feed in seagrass pastures in theGulf of California.[46] Green turtles belonging to the distinct Hawaiian subpopulation nest at the protectedFrench Frigate Shoals some 800 kilometers (500 mi) west of the Hawaiian Islands.[24]
In thePhilippines, green turtles nest in theTurtle Islands along with closely relatedhawksbill turtles.[47] In December 2007, fishermen using ahulbot-hulbot (a type offish net) accidentally caught an 80 kg (180 lb), 93 cm (37 in) long and 82 cm (32 in) wide turtle off Barangay Bolong,Zamboanga City,Philippines. December is breeding season near the Bolong beach.[48]
An annual presence is recorded in the Gulf of Panama, on the Isla Parida island. Local activists also moving some turtle nests to the coast, in the vicinity of the small town of Malena, to save and increase the turtle population in the safe place.[49]
The population that has often been known as the Galápagos green turtle have been recorded and observed in the Galápagos as far back as the 17th century byWilliam Dampier.[58] Not much attention has been paid to them due to the overwhelming research done on theGalápagos giant tortoises.[59] Only over the last 30 years have extensive studies been performed covering the behaviors of the Galápagos green turtles. Much of the debate that has surrounded them recently is over the binomial classification of the species.[60] At one point the nameChelonia agassizii was applied to this population as a separate species.[19] Analysis ofmitochondrial andnuclear DNA of 15 nesting beaches,[60] however, has demonstrated that there is not only no significant distinction of this population but that it would be paraphyletic to recognise it. As such the species nameChelonia agassizzii is considered a junior synonym ofChelonia mydas[60] as such it is considered as a local variant of the populations of the East Pacific waters and those of other nesting areas.[60]
The morphological distinctiveness of the Galápagos green turtle has given rise to the debate,[19] but evidence of taxonomic distinctiveness is best served using the combination of multiple datasets. The two most notable morphological distinctions are the considerably smaller adult size and the much darker pigmentation of the carapace, plastron, and extremities.[19] Other distinctions are the curving of the carapace above each hind flipper, the more dome-shaped carapace, and the very long tail of adult males.[61] Three possibilities have arisen from their unique characteristics:agassizii is a separate species fromC. mydas, it is a subspecies of green sea turtle, or it is simply a color mutation.[61] These facts have led to the debate over binomial separation however due to the significance of the DNA testing results there have been no distinctions made at this time.[60] At a meeting for sea turtle scientists and their collaborators in 2000, the evidence for the taxonomic position of the Galápagos green turtle was reviewed and a majority among the participants supported treating it as a population or subspecies of the green turtle (instead of a separate species).[62] However, this is possibly a case of political taxonomy. As such the three major international checklists that cover turtles of the worldReptile Database[63] the checklist of Fritz and Havas (2007)[4] and the IUCN Checklist (TTWG 2017)[64] all consider this a junior synonym.
Green sea turtles move across threehabitat types, depending on theirlife stage. They lay eggs on beaches. Mature turtles spend most of their time in shallow, coastal waters with lush seagrass beds. Adults frequent inshore bays, lagoons, and shoals with lushseagrass meadows. Entire generations often migrate between one pair of feeding and nesting areas.[26] Green sea turtles,Chelonia mydas, are classified as an aquatic species and are distributed around the globe in warm tropical to subtropical waters. The environmental parameter that limits the distribution of the turtles is ocean temperatures below 7 to 10 degrees Celsius.[65] Within their geographical range, the green sea turtles generally stay near continental and island coastlines. Near the coastlines, the green sea turtles live within shallow bays and protected shores. In these protected shores and bays, the green sea turtle habitats include coral reefs, salt marshes, and nearshore seagrass beds. The coral reefs provide red, brown, and green algae for their diet and give protection from predators and rough storms within the ocean. The salt marshes and seagrass beds contain seaweed and grass vegetation, allowing ample habitat for the sea turtles.[35]
Turtles spend most of their first five years in convergence zones within the bare open ocean that surround them.[10][66] These young turtles are rarely seen as they swim in deep,pelagic waters.[67][68] Green sea turtles typically swim at 2.5–3 km/h (1.6–1.9 mph).[69]
As one of the first sea turtle species studied, much of what is known of sea turtle ecology comes from studies of green turtles. The ecology ofC. mydas changes drastically with each stage of its life history. Newly emerged hatchlings arecarnivorous,pelagic organisms, part of the open ocean mininekton. In contrast, immature juveniles and adults are commonly found inseagrass meadows closer inshore asherbivorous grazers.
Only some human beings and the largersharks feed onC. mydas adults. Specifically,tiger sharks (Galeocerdo cuvier) hunt adults in Hawaiian waters.[77] The tiger shark is the main predator of the green turtle as it will prey on green turtles of all sizes. The tiger shark has often been seen feeding on green turtles near their nesting beaches because they are restricted in the area of their nesting beaches and vulnerable to predation.[78] Juveniles and new hatchlings have significantly more predators, includingcrabs, smallmarine mammals andshorebirds.[7] Additionally, their eggs are vulnerable to predation by scavengers likered foxes andgolden jackals.[79]
Green sea turtles have a variety of parasites includingbarnacles,leeches,protozoans,cestodes, andnematodes. Barnacles attach to the carapace, and leeches to the flippers and skin of the turtles, causing damage to the soft tissues and leading to blood loss. Protozoans, cestodes and nematodes lead to many turtle deaths because of the infections in the liver and intestinal tract they cause. The greatest disease threat to the turtle population isfibropapilloma, which produces lethal tumor growth on scales, lungs, stomach, and kidneys. Fibropapilloma is caused by a herpesvirus that is transmitted by leeches such asOzobranchus branchiatus, a species of leech which feeds almost entirely on green sea turtles.[65][80]
Green sea turtles migrate long distances between feeding sites and nesting sites; some swim more than 2,600 kilometres (1,600 mi) to reach their spawning grounds. Beaches in Southeast Asia, India, islands in the western Pacific, and Central America are where green sea turtles breed.[8] Mature turtles often return to the exact beach from which they hatched. Females usually mate every two to four years. Males, on the other hand, visit the breeding areas every year, attempting to mate.[81] Mating seasons vary between populations. For mostC. mydas in theCaribbean, mating season is from June to September.[26] TheFrench Guiana nesting subpopulation nests from March to June.[41] In the tropics, green turtles nest throughout the year, although some subpopulations prefer particular times of the year. InPakistan,Indian Ocean turtles nest year-round, but prefer the months of July to December.[56]
Sea turtles return to the beaches on which they were born to lay their own eggs. The reason for returning to native beaches may be that it guarantees the turtles an environment that has the necessary components for their nesting to be successful. These include a sandy beach, easy access for the hatchlings to get to the ocean, the right incubation temperatures, and low probability of predators that may feed on their eggs. Over time these turtles have evolved these tendencies to return to an area that has provided reproductive success for many generations. Their ability to return to their birthplace is known asnatal homing.[82] The males also return to their birthplaces in order to mate. These males that return to their homes know they will be able to find mates because the females born there also return to breed. By doing this, the green sea turtles are able to improve their reproductive success and is why they are willing to expend the energy to travel thousands of miles across the ocean in order to reproduce.
Mating behaviour is similar to other marine turtles. Female turtles control the process. A few populations practicepolyandry, although this does not seem to benefit hatchlings.[83] After mating in the water, the female moves above the beach's high tide line, where she digs a hole 28–56 centimetres (11–22 in) in depth with her hind flippers and deposits her eggs. The hole is then covered up again.[84] Clutch size ranges between 85 and 200, depending on the age of the female. This process takes about an hour to an hour and a half. After the nest is completely covered, she returns to the sea. The female will do this 3 to 5 times in one season.[8]
Green sea turtle hatchlings on the beach
The eggs are round and white, and about 45 mm (1.8 in) in diameter. The hatchlings remain buried for days until they all emerge together at night.[84] The temperature of the nestdetermines the sex of the turtles at around the 20–40 day mark. Green Sea Turtles are type 1a, meaning males develop at cooler temperatures while females are produced under hot temperatures.[85][86] At around 50 to 70 days,[87] the eggs hatch during the night, and the hatchlingsinstinctively head directly into the water. This is the most dangerous time in a turtle's life. As they walk, predators, such asgulls andcrabs, feed on them. A significant percentage never make it to the ocean. Little is known of the initial life history of newly hatched sea turtles.[26] Juveniles spend three to five years in the open ocean before they settle as still-immature juveniles into their permanent shallow-water lifestyle.[67][68] It is speculated that they take twenty to fifty years to reachsexual maturity. Individuals live up to eighty years in the wild.[7] It is estimated that only 1% of hatchlings reach sexual maturity.
Each year onAscension Island in theSouth Atlantic,C. mydas females create 6,000 to 25,000 nests. They are among the largest green turtles in the world; many are more than 1 metre (3 ft 3 in) in length and weigh up to 300 kilograms (660 lb).[88]
Sea turtles spend almost all their lives submerged, but must breathe air for the oxygen needed to meet the demands of vigorous activity. With a single explosive exhalation and rapid inhalation, sea turtles can quickly replace the air in their lungs. The lungs permit a rapid exchange of oxygen and prevent gases from being trapped during deep dives. Sea turtle blood can deliver oxygen efficiently to body tissues even at the pressures encountered during diving. During routine activity, green and loggerhead turtles dive for about four to five minutes, and surface to breathe for one to three seconds.
Turtles can rest or sleep underwater for several hours at a time, but submergence time is much shorter while diving for food or to escape predators. Breath-holding ability is affected by activity and stress, which is why turtles quickly drown inshrimp trawlers and other fishing gear.[32] During the night while sleeping and to protect themselves from potential predators, the adults wedge themselves under rocks below the surface and under ledges in reefs and coastal rocks. Many green sea turtles have been observed in returning to the same sleeping location night after night.[35]
Green sea turtles tend to have good vision, well adapted to a life at sea. The turtles can see many colors, but are most sensitive to light from violet to yellow or wavelengths of 400 to 600 nanometers. They do not see many colors in the orange to red portion of the light spectrum. On land, however, the sea turtles are nearsighted because the lenses in the eyes are spherical and adjusted to refraction underwater.[35] Sea turtles have no external ear and only one ear bone, called the columella. With one ear bone, the turtles can hear only low frequency sounds, from 200 to 700 Hz. Sounds can also be detected through vibrations of the head, backbone, and shell. The nose of the turtle has two external openings and connects to the roof of the mouth through internal openings. The lower surface of the nasal passage has two sets of sensory cells called the Jacobson's organ. The turtle can use this organ to smell by pumping water in and out of its nose.[65]
Since green sea turtles migrate long distances during breeding seasons, they have special adaptive systems in order to navigate. In the open ocean, the turtles navigate using wave directions, sun light, and temperatures. The sea turtles also contain an internal magnetic compass. They can detect magnetic information by using magnetic forces acting on the magnetic crystals in their brains. Through these crystals, they can sense the intensity of Earth's magnetic field and are able to make their way back to their nesting grounds or preferred feeding grounds.[65]
Natal homing is an animal's ability to return to its birthplace in order to reproduce. Natal homing is found in all species of sea turtles and in other animals such as salmon. How these turtles are able to return to their birthplace is an interesting phenomenon. Many researchers believe that sea turtles use a process called imprinting, which is a special type of learning that occurs when turtles first hatch that allows them to recognize their native beach. There are two types of imprinting that are thought to be the reason turtles can find these beaches. The first is the chemical imprinting hypothesis. This hypothesis states that much like salmon, sea turtles are able to use olfactory cues and senses to smell their way home. However, a problem with this hypothesis is that some turtles travel thousands of miles to return to their native beaches, and the scents from that area are not likely to travel and be distinguishable from that distance.The second hypothesis is the geomagnetic. This hypothesis states that as it hatches, a young turtle will imprint on the magnetic field of the beach they are born on. This hypothesis strongly correlates to the method which sea turtles use to navigate the earth.[82]
In order to tolerate the constant heat loss in the water, sea turtles have the ability to shunt blood away from tissues that are tolerant of low oxygen levels toward the heart, brain, and central nervous system. Other mechanisms include basking on warm beaches and producing heat through their activity and movements of their muscles. Basking turtles sometimes look like they are crying because behind the turtles eye is the lachrymal gland which stores excess salt from the sea water, which then expels through the turtles eye. In the winter months, turtles living at higher latitudes can hibernate for a short period in the mud.[89]
Green sea turtles can reach up to 40 miles per hour when swimming, making them the fastest sea turtle.[90] The green sea turtles exhibit sex differences by their development and appearance. As adult turtles, males are easily distinguishable from the females by having a longer tail (visibly extending past the shell) and longer claws on the front flippers. The hatching time and sex of the turtles are determined by the incubation temperature of the nest. Hatchings occur more quickly in nests that are warmer than nests that are in cooler conditions. Warm nesting sites above 30 degrees Celsius favor the development of females, whereas nesting sites below 30 degrees Celsius produce males. The position of the egg in the nest also affects sex-determination. Eggs in the center tend to hatch as females due to the warmer conditions within the nest.[35]
Green sea turtles play an essential role in the ecosystem in which they live. In the seagrass beds, the turtles feed on the seagrass by trimming only the top and leaving the roots of the plant. Through their feeding technique, the turtles help to improve the health and growth of the seagrass beds. The healthy seagrass beds that the turtles provide give habitat and feeding grounds for many species of fish and crustaceans. On the nesting beaches, the green sea turtles provide key nutrients for the ecosystem through their hatched egg shells. In their coral reef habitat, the green sea turtles have asymbiotic interaction with reef fish, including the yellow tang. The yellow tang fish swims along with the turtle and feeds on the algae, barnacles, and parasites on its shell and flippers. This species interaction provides food for the yellow tang and provides a necessary cleaning and smoothing of the turtle's shell. This cleaning helps the turtles swim by reducing the amount of drag and improves their health.[65]
Harvested green turtles on a wharf atKey West, Florida
Historically, the turtles' skin wastanned and used to makehandbags, especially inHawaii.[24]Ancient Chinese considered the flesh of sea turtles a culinary delicacy, including and especiallyC. mydas.[91] Particularly for this species, the turtle'sfat,cartilage, and flesh, known ascalipee, are sought as ingredients for makingturtle soup, a popular 19th-century English and American dish.[92][93][22]
InJava,Indonesia, sea turtle eggs were a popular delicacy. However, the turtle's flesh is regarded asḥarām or "unclean" underIslamic law (Islam is Java's primary religion). InBali, turtle meat was a prominent feature at ceremonial and religious feasts. Turtles were harvested in the remotest parts of theIndonesian archipelago.[94] Bali has been importing sea turtles since the 1950s, as its own turtle supplies became depleted.[95] The mostly HinduBalinese do not eat the eggs, but sell them instead to localMuslims.
Green Sea Turtle skeleton in the collection of theMuseum Alexandre-Franconie, Cayenne,French Guiana
Commercial farms, such as theCayman Turtle Farm in theWest Indies, once bred them for commercial sale of turtle meat, turtle oil (rendered from the fat), turtle shell, and turtle leather made from the skin. The farm's initial stock was in large part from "doomed" eggs removed from nests threatened by erosion, flooding, or in chemically hostile soil.[96] The farms held as many as 100,000 turtles at any one time. When the international markets were closed by regulations that did not allow even farm-bred turtle products to be exported internationally, the surviving farm became primarily a tourist attraction, supporting 11,000 turtles.[97] Initially started as Mariculture Ltd., then Cayman Turtle Farm Ltd and subsequently branded Boatswain's Beach, in 2010 the farm's brandname was changed to Cayman Turtle Farm: Island Wildlife Encounter.[98]
Sea turtles are integral to the history and culture of theCayman Islands. When the islands were first discovered byChristopher Columbus in 1503, he named them "Las Tortugas" because of the abundance of sea turtles in the waters around the islands.[99] Many of the earliest visitors came to theCayman Islands to capture the turtles as a source of fresh meat during long voyages. The green turtle is a national symbol displayed as part of thecoat of arms of the Cayman Islands, which also forms part of the nationalflag of the Cayman Islands. The country's currency uses a turtle as the watermark in its banknotes.[100] A stylised sea turtle nicknamed "Sir Turtle" is the mascot of the national airlineCayman Airways[101] and is part of the livery of its aircraft.
A ki'i pōhaku (petroglyph) of a green sea turtle (or honu) can be found on theBig Island of Hawaii in the Pu'u Loa lava fields. The green sea turtle has always held a special meaning forHawaiians and this petroglyph shows its importance; it may date to when theHawaiian Islands first became populated. The turtle symbolizes a navigator that can find his way home time after time. This symbol mirrors the real life of the green Hawaiian turtle as it will swim hundreds of miles to lay its eggs at its own place of birth. Though there are other myths as well, some Hawaiian legends say the honu were the first to guide thePolynesians to the Hawaiian Islands. Hawaiians revere the turtle and the legend of Kailua, a turtle who could take the form of a girl at will. In human form, she looked after the children playing onPunaluʻu Beach.[102]
Sea turtles have moved from unrestricted exploitation to global protection, with some individual countries providing additional protection, although serious threats remain.[103][104] In 2025, theInternational Union for Conservation of Nature (IUCN)reclassified the global population of green sea turtles fromendangered toleast concern, though some sub-populations remain a conservation concern.[104][105]
Human action presents both intentional and unintentional threats to the species' survival. Intentional threats include continuedhunting,poaching and egg harvesting. More dangerous are unintentional threats, including boat strikes, fishermen's nets that lackturtle excluder devices,pollution andhabitat destruction. Chemical pollution may createtumors;[106]effluent fromharbors near nesting sites may create disturbances; andlight pollution may disorient hatchlings. With chemical pollution present, there is a development of tar balls that is often eaten by green sea turtles in a confusion of their food. Tar balls cause the green sea turtle to ingest toxins that can block their guts and cause swelling of the tissue, displacing the liver and intestines.[107] Habitat loss usually occurs due to human development of nesting areas. Beach-front construction, land "reclamation" and increased tourism are examples of such development.[7][10] An infectioustumor-causing disease,fibropapillomatosis, is also a problem in some populations. The disease kills a sizeable fraction of those it infects, though some individuals seem to resist the disease.[24][108][109] In addition, at least in the Southwestern Atlantic (Río de la Plata, Uruguay), exotic invasive species such as the rapa whelkRapana venosa, were reported massively bio-fouling immature green turtles, reducing buoyancy, increasing drag, and causing severe injuries to the carapace.[110] Because of these threats, many populations are in a vulnerable state.
Pacific green turtles' foraging habitats are poorly understood and mostly unknown.[111] These foraging grounds are most likely along the coast of Baja California, Mexico and southern California,[112] in which these turtles have a high risk of incidental capture by coastal fisheries. The main mortality factor for these turtles is the shrimp trawlers in Mexico, in which many of these turtles go undocumented.[112] The only foraging area that has been identified is San Diego Bay, but it is heavily polluted with metals and PCBs.[112] These contaminants have a negative effect on the ocean environment, and have been shown to cause lesions and sometimes mortality.[112] Green turtles also are threatened by entanglement and ingestion of plastic.[112] In San Diego Bay, an adult green turtle was found dead with monofilament netting tightly packed in its esophagus.[112] In addition there are indications that global climate change is affecting the ability of green turtle populations in Australia to produce males due to theirtemperature-dependent sex determination and the rising temperatures in the northernGreat Barrier Reef region.[113] Construction of newthermal power stations can raise local water temperature, which is also said to be a threat.[114]
Green sea turtles are the most commonly traded species along Java's south coast and are sold in the form of whole, stuffed animals or turtle oil, locally known as "minyak bulus".[115]
The geographer James J. Parsons' book titledThe Green Turtle and Man played a special role in the conservation movement to save the species from extinction.[116]
In 2001,Nicholas Mrosovsky filed a delisting petition, claiming some green turtle populations were large, stable and in some cases, increasing. At the time, the species was listed under the strict EN A1abd criteria. The IUCN Standards and Petitions Subcommittee ruled that visual counts of nesting females could not be considered "direct observation" and thus downgraded the species' status to EN A1bd—retaining the turtle's endangered status.[123]
In 2004, the IUCN reclassifiedC. mydas as endangered under the EN A2bd criteria, which essentially states the wild populations face a high risk ofextinction because of several factors. These factors include a probable population reduction of more than 50% over the past decade as estimated from abundance indices and by projecting exploitation levels.[124]
On 3 May 2007,C. mydas was listed on Appendix I of theConvention on International Trade in Endangered Species (CITES) as a member of the familyCheloniidae.[125] The species was originally listed on Appendix II in 1975. The entire family was moved to Appendix I in 1977, with the exception of theAustralian population ofC. mydas. In 1981, the Australian population joined the rest. The Appendix I listing prohibits commercial international trade in the species (including parts and derivatives).[126] TheZoological Society of London has listed the reptile as anEDGE species.[127]
In October 2025, the IUCN amended green turtle conservation status to "least concern"[128], though some subpopulations remain at risk. TheMediterranean population is listed as critically endangered.[7][22] The eastern Pacific, Hawaiian and Southern California subpopulations are designated threatened. Specific Mexican subpopulations are listed as endangered. The Florida population is listed as endangered. TheWorld Wide Fund for Nature has labeled populations in Pakistan as "rare and declining".[57]
Since 1999, theFlorida Aquarium has led extensive sea turtle rehabilitation efforts and visitor and community education & conservation platforms to advance sea turtle protection. Over a 20-year period, the aquarium received 200 sea turtles, and while not all could be released due to the nature of their injuries or illnesses, 180 were successfully released. In 2019, they opened a state-of-the-art Sea Turtle Rehabilitation Center inApollo Beach, Florida. In the first year, The Florida Aquarium Animal Response Team managed the care of 21 sea turtles, initiated new foraging-readiness testing for release candidates in deep-dive tank, and released 14 animals. In 2020, they also initiated a study to better understand how micro-plastics are impacting the sea turtles in their care. In 2016,Florida enacted extensive protection measures. Florida statutes (F.A.C. Rule 68E-1) restrict the take, possession, disturbance, mutilation, destruction, selling, transference, molestation, and harassment of marine turtles, nests or eggs. Protection is also afforded to marine turtle habitat. A specific authorization from commission staff is required to conduct scientific, conservation, or educational activities that directly involve marine turtles in or collected fromFlorida, their nests, hatchlings or parts thereof, regardless of applicant's possession of any federal permit.
In the State ofHawaii, specifically on the Island of Hawaiʻi (Hawaii County), state representativeFaye Hanohano, a Native Hawaiian rights activist, pressed for a measure to delistC. mydas from protected status so that Native Hawaiians could legally harvest the turtles and possibly their eggs as well. The bill, HCR14, was largely overlooked by the media since at that point it was only a local issue. While the bill was passed in theUnited States House of Representatives, theUnited States Senate's Committee on Energy and Environment refused to hear it, which meant that the bill did not go on to be heard by the Senate.[129]
At theOsaka Aquarium, profile photo of turtle resting on bottom
In addition to management by global entities such as theIUCN andCITES, specific countries around the world have undertaken conservation efforts.
TheIndonesian island ofBali has traditional uses that were considered sustainable, but have been questioned considering greater demand from the larger and wealthier human population. The harvest was the most intensive in the world.[94] In 1999, Indonesia restricted turtle trade and consumption because of the decreasing population and threat of a tourist boycott. It rejected a request made by Bali GovernorI Made Mangku Pastika in November 2009 to set a quota of 1,000 turtles to be killed inHindu religious ceremonies. While conservationists respect the need for turtles in rituals, they wanted a smaller quota.[130]
Multipleprotected areas of the Philippines have significant green sea turtle nesting and feeding sites. The most notable isTurtle Islands Wildlife Sanctuary, anUNESCO tentative site which encompasses an entire municipality and one of Southeast Asia's most important green sea turtle nesting sites.[131] Other notable sites include theUNESCO tentative site of El Nido-Taytay Management Resource Protected Area and theUNESCOWorld Heritage Site of Tubbataha Reefs Natural Park. The species is protected under Republic Act 9147 or the Wildlife Resources Conservation and Protection Act, while the sites where they live and nest are protected under the National Integrated Protected Areas System Act.[132]
Ecotourism is one initiative inSabah,Malaysia. The island ofPulau Selingan is home to a turtlehatchery. Staff people place some of the eggs laid each night in a hatchery to protect them from predators. Incubation takes around sixty days. When the eggs hatch,tourists assist in the release of the baby turtles into the sea.[133]
TheHawaiian subpopulation has made a remarkable comeback and is now one focus of ecotourism and has become something of a statemascot. Students ofHawaii Preparatory Academy onthe Big Island have tagged thousands of specimens since the early 1990s.[24]
In the Atlantic, conservation initiatives have centered around Caribbean nesting sites. The Tortuguero nesting beaches inCosta Rica have been the subject of egg-collection limits since the 1950s. TheTortuguero National Park was formally established in 1976, in part, to protect that region's nesting grounds.[38] OnAscension Island, which contains some of the most important nesting beaches, an active conservation program has been implemented.[135] Karumbé has been monitoring foraging and developmental areas of juvenile green turtles in Uruguay since 1999.[136]
In Mozambique, there are a number of initiatives to protect sea turtles. In thePrimeiras e Segundas,WWF Mozambique has established a turtle tagging and protection program. The archipelago is a vital nesting area for green turtles, includingIlha do Fogo where Earth Legacy Foundation[137] manage a turtle monitoring programme, and at Celdeira Island, where several nesting females have been tagged.
Cayman Turtle Farm located in Grand Cayman in the northwest Caribbean Sea is the first farm to have achieved the second generation of green sea turtles bred, laid, hatched, and raised in captivity.[138] Since its beginning in 1968, the farm has released over 31,000 turtles into the wild,[99] and each year more captive-bred turtles are released into theCaribbean Sea from beaches around the island ofGrand Cayman.[139] Captive-bred turtles released from the farm as hatchlings or yearlings with "living tags," have now begun to return to nest on Grand Cayman as adults.[140][141] On February 19, 2012 the farm released the first 2nd-generation captive-bred green sea turtle equipped with a Position Tracking Transponder, or PTT[142] (also known as a satellite tag).[143] In addition, the farm provides turtle meat products to the local population for whom turtle has been part of the traditional cuisine for centuries. In so doing, the farm curtails the incentive to take turtles from the wild,[144] which over the years in addition to the Cayman Turtle Farm's release of captive-bred turtles has enabled an increase in the number of turtles sighted in the waters around the island ofGrand Cayman and nesting on its beaches.[145]
United States Fish and Wildlife Service measures sea turtle eggs
In the Pacific, green sea turtles nest on themotu (islets) in theFunafuti Conservation Area, a marine conservation area covering 33 square kilometers (12.74 square miles) of reef, lagoon andmotu on the western side ofFunafuti atoll inTuvalu.[146]
OnRaine Island, up to 100,000 nesting females have been observed in a season, with the cay producing 90% of the region's green turtles. However, the hatching rate declined in the 1990s, and a further decline in the population was threatened by the deaths of thousands of females as they struggled to climb the small sandy cliffs. In addition, as the shape of the island had changed over time, the spread of the beaches outwards had led to greater risk of inundation of the turtle nests. Between 2011 and 2020, a collaborative project by theQueensland Government,BHP (as corporate sponsor), the Great Barrier Reef Marine Park Authority, Great Barrier Reef Foundation, andWuthathi andMeriamtraditional owners, reshaped the island using heavy machinery in a way that gave the female turtles a smoother passage and reduced the risk of nest inundation. A sophisticated monitoring and research system, using3D modelling,satellite technology anddrones was employed, and monitoring continues.[147]
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^Connolly, Norma (June 2, 2011)."More turtles nesting in Cayman".Caymanian Compass. Archived fromthe original on September 23, 2015. RetrievedApril 9, 2012.five turtles with tags from the Cayman Turtle Farm were observed nesting on Seven Mile Beach
^Brammer, Jeff (October 16, 2011)."What if the turtle farm went belly up?".Caymanian Compass. Archived fromthe original on September 23, 2015. RetrievedApril 9, 2012.presenting disincentives to poachers due to the commercial availability of turtle meat
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