Chelonia mydas

Green turtles are long-lived and may take up to 59 years to reach sexual maturity (6) Undertaking tremendous feats of navigation, adults return to the same beach to breed each season, part of the population in Brazil astonishingly migrates around 2,250 kilometres across the open ocean to breed on the Ascension Islands (12). Mating tends to occur just offshore of the nesting beaches; using a curved claw on each front flipper and a flat nail at the end of the tail, males are able to grip their mates (2). Females haul out onto the beach at night and dig large nests with their back flippers beyond the high tide mark, they typically lay between 100 and 150 eggs in one nest and then proceed to cover the eggs with sand; the whole process takes around two hours (6). A single female returns to breed only once every two to five years but will lay up to nine nests in that one season (2). Incubation takes between 45 and 70 days, and temperature has been shown to determine of the sex of hatchlings; with females being produced at warmer temperatures (6). Breaking open their eggs with a special hooked 'egg tooth' that will subsequently be lost; hatchlings use their powerful front flippers to reach the surface, and then proceed to the sea (7). The soft-bodied juveniles are particularly vulnerable at this time from a variety of predators, such as ghost crabs and gulls on the beach to sharks and dolphins in the water (7). Unlike other marine turtles, adult green turtles are almost exclusively herbivorous, grazing on seagrasses and algae (8); it is assumed that juveniles are more omnivorous although the exact composition of their diet is unknown (6)

Green turtles are one of the largest and most widespread of all the marine turtles (5). The oval carapace varies from olive to brown, grey and black with swirls and irregular patters (6), but the common name is derived from the green colour of the fat and connective tissues of this species (2). Two subspecies are currently recognised; the Pacific green turtle (Chelonia mydas agassizii) tends to be smaller than its Atlantic cousin (C. m. mydas) with a narrower carapace that may sometimes be completely black, providing the other common name of 'black turtle' to certain populations (7). The plastron, or undershell, remains a pale yellow or orange throughout life (6). Males are generally smaller than females (11), and green turtles differ in appearance from other marine turtles by the possession of a single pair of scales in front of the eyes and a serrated bottom jaw (2). The tiny black hatchlings are only around 50 millimetres long (6).

Green sea turtles lead hard and dangerous lives, and are lucky to reach adulthood. They spend most of their lives in the water, but female green sea turtles need to come on land to lay their eggs. Once they have crawled onto the beach, they dig a hole for hours until their flippers are exhausted, lay 100 to 200 eggs inside it, and then cover it up to protect the eggs from heat and predators. When the eggs hatch, the baby turtles have to crawl to the sea, but because there are so many animals that eat them, not many of them survive the trip. The lucky ones that make it to the water spend their early life trying to avoid being eaten by dolphins and sharks. Adult sea turtles spend a life of well-earned rest among seagrass beds and coral reefs.

A large marine turtle, reaching up to 1,200 mm in carapace length; largest Egyptian specimen is 1,190 mm. Carapace depressed, rounded, smooth; scutes juxtaposed; posterior edge without indentations; 4 coastal scutes; first marginal scute in contact with first vertebral scute. Head relatively small with a single pair of prefrontals. C. mydas differs from all other marine turtles in possessing serrations on the lower jaw, which facilitate grazing on marine grasses. Forelimbs and hind limbs have a single claw each. Males smaller, with longer tails and larger claws. Color of carapace light brown with dark streaks radiating out from a point at the posterior margin of each scute. Dorsal sides of limbs and head brown, each scale edged yellowish. All ventral sides whitish yellow.

 The green turtle is the largest hard-shelled sea turtle, it has a carapace (shell) up to 1.4 m in length and can weigh a total of 180 kg. The green turtles smooth carapace, small rounded head and four pairs of scales (costal scutes) is what distinguishes it from other sea turtles. The shell of this species varies in colour from olive to brown, grey and black with swirls and irregular patterns.The green turtle is protected form international trade by its listing on Appendix I of the Convention on International Trade in Endangered Species (CITES). Populations of green turtles are in serious decline due to a number of factors. These include loss of nesting habitats, destruction of nests by poachers, propeller wounds, interaction with commercial fisheries and ingestion of marine debris, demand for their eggs and meat for human consumption.

Green sea turtles are the most common sea turtles, and can be found in warm waters. They have been spotted in tropical waters around 139 different countries. Their body shape and paddle-shaped flippers make them excellent swimmers. They have been known to swim over 1,400 miles (2,253 km) from their feeding ground to their nesting site! They also have good memory; when the time comes to build their nests and lay their eggs, they return to the same sandy beach where they were born. No one knows how long they live, but people think they can live to be around 100 years old!

Green turtles are found in tropical and portions of subtropical oceans worldwide. They are found in the Atlantic Ocean from the eastern United States along coastal South America to South Africa. They are found throughout the Caribbean Sea and portion of the Mediterranean. They are also found throughout the warm waters of the Indian and Pacific Oceans.

Biogeographic Regions: indian ocean (Native ); atlantic ocean (Native ); pacific ocean (Native ); mediterranean sea (Native )

Green turtles are found in tropical waters around the globe, particularly associated with the coastline (8).

The Green Turtle has a circumglobal distribution, occurring throughout tropical and, to a lesser extent, subtropical waters (Atlantic Ocean – eastern central, northeast, northwest, southeast, southwest, western central; Indian Ocean – eastern, western; Mediterranean Sea; Pacific Ocean – eastern central, northwest, southwest, western central). Green turtles are highly migratory and they undertake complex movements and migrations through geographically disparate habitats. Nesting occurs in more than 80 countries worldwide (Hirth 1997). Their movements within the marine environment are less understood but it is believed that green turtles inhabit coastal waters of over 140 countries (Groombridge and Luxmoore 1989).

cosmopolitan warm water

Distribution extends northward of the subprovince limit of Carolinian, Cape Hatteras through Florida

Known from Egyptian waters in both the Mediterranean and Red Sea. The only reliable evidence of nesting on the Mediterranean shores is a nest with eggs found near Zaranik, North Sinai, in the summer of 1998 (Clarke et al. 2000). A dead juvenile (carapace length 85 mm) found at Baltim could have originated from elsewhere. Dead individuals are frequently encountered throughout the Egyptian Mediterranean shoreline. In the Red Sea the species has been recorded from both the Gulfs of Suez and Aqaba, and has been reported to have nested at Ras Sharatib, south of Abu Rudeis (where some 80 females were estimated to nest),Tiran Island, Qulan Islands, Wadi El Gemal Island, Ras Banas, and Zabargad Island. Eggs and embryos from Giftun El Kebir Island referred to this species by Marx (1968), were re-identified as Eretmochelys imbricata by (Frazier and Salas 1984). The species nests sporadically along the mainland shores of the Red Sea south of Marsa Alam, where almost a hundred nests have been found between Ras Baghdadi and Marsa um El Abbas.

Circum-global, largely within the 20°c oceanic isotherms.

occurs (regularly, as a native taxon) in multiple nations

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: Distribution is pantropical in the Atlantic, Pacific, and Indian oceans. In some areas this species occurs in higher temperate latitudes due to drifting in ocean currents in conjunction with above-normal sea temperatures or as a normal life history event; young turtles regularly range as far north as New England. Major nesting activity occurs on Ascension Island, Aves Island, in Costa Rica (24,000 females nests each year at Tortuguero), and in Surinam (CSTC 1990). See Hirth (1980) for a map of major nesting beaches.

In U.S. Atlantic waters, green sea turtles occur around the U.S. Virgin Islands and Puerto Rico, where small numbers nest (islas Mona, Vieques, and Culebra, and St. Thomas, St. John, St. Croix), and a juvenile population exists in eastern portion of Puerto Rican Bank (Collazo et al. 1992), and from Texas to Massachusetts. Relatively small numbers nest in Florida, particularly in Brevard, Indian River, St. Lucie, Martin, Palm Beach, and Broward counties (CSTC 1990), mostly from Volusia County to Dade County (Ehrhart and Witherington 1992), with rare recent nesting on the Gulf Coast in Santa Rosa County (Ehrhart and Witherington 1992); important feeding areas in Florida include the Indian River, Florida Bay, Homossassa Bay, Crystal River, and Cedar Key (CSTC 1990). Rarely nests in Georgia, North Carolina, and Texas.

Continent: Africa Oceania Near-East Middle-America Asia Caribbean South-America Europe Australia North-America
Distribution: Atlantic, Pacific, and Indian oceans, chiefly in the tropics.  Europe: Adriatic Sea (Croatia ?), Italy (occasional occurence [E. RAZZETTI, pers. comm.]) Turkey [Basoglu 1973], France, Portugal  Indian Ocean: Madagascar, Comoro Islands (Grande Comore, Mohélim Anjouan, Mayotte), Chagos Archipelago  Pacific: as far north as Alaska and in the   Atlantic Ocean: as far north as Great Britain, Gambia  Australia (New South Wales?, North Territory, Queensland, West Australia), Nauru?  Americas: Canada (British Columbia), USA SE Mexico (Yucatan, Baja California), Belize, Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica,  Panama, Colombia [Castro,F. (pers. comm.)], Argentina  Asia: Korea, Andaman Islands, Nicobar Islands  mydas: Atlantic Ocean  agassizi: eastern Pacific Ocean, Galapagos Islands. Hawaii (USA) and Papua New Guinea;
Type locality: "l'en bouchure du Nagualated, dans le Pacifique (Guatémala)" [Embayment of Río Nagualate, Guatemala].  japonica: Indian and Western Pacific Ocean  acording to the 1994 IUCN Red List of Threatened Animals: EC/NE/NW/SE/SW/WC Atlantic, Indian Ocean eastern, Indian Ocean western, Mediterranean and Black Sea, EC/NW/SW/WC Pacific,  American Samoa, Angola, Anguilla, Antigua and Barbuda, Australia, Bahamas, Bangladesh, Belize, Benin, Brazil, British Indian Ocean Territory, Cambodia, Cameroon, Cape Verde, Chile, China, Colombia, Comoros, Congo, Cook Islands, Costa Rica, Cote d'Ivoire, Cuba, Cyprus, Djibouti, Dominica, Dominican Republic, Ecuador, Egypt, El Salvador, Equatorial Guinea, Eritrea, Federated States of Micronesia, Fiji, French Guiana, French Polynesia, Gabon, Ghana, Grenada, Guadeloupe, Guam, Guatemala, Guinea, Guinea-Bissau, Guyana, Haiti, Honduras, India, Indonesia, Iran, Israel, Jamaica, Japan, Kenya, Kiribati, Kuwait, Liberia, Madagascar, Malaysia, Maldives, Marshall Islands, Martinique, Mauritania, Mauritius, Mayotte, Mexico, Montserrat, Mozambique, Myanmar (= Burma), Netherlands Antilles, New Caledonia, Nicaragua, Nigeria, Niue, Northern Marianas, Oman, Pakistan, Palau, Panama, Papua New Guinea, Peru, Philippines, Puerto Rico, Qatar, Reunion, Sao Tome & Principe, Saudi Arabia, Senegal, Seychelles, Sierra Leone, Solomon Islands, Somalia, Sri Lanka, St Helena, St Kitts and Nevis, St Lucia, St Vincent, Sudan, Suriname, Taiwan, Tanzania, Thailand, Togo, Tokelau, Tonga, Trinidad and Tobago, Turkey, Turks and Caicos Islands, Tuvalu, US Minor Pacific Islands, USA (Washington; Western Atlantic: Maine, New Hampshire, Massachusetts,  Connecticut, New Jersey, Delaware, Maryland, Virginia, North Carolina, South Carolina, Georgia, Florida), United Arab Emirates, Vanuatu, Venezuela, Viet Nam, Virgin Islands (British), Virgin Islands (US), Western Sahara, Western Samoa, Yemen, Zaire  
Type locality: “insulas Pelagi: insularum Adscensionis" [The Pelagie Islands and Ascencion Island]; restricted to Ascension Is., see Mertens, R. & Müller, L. (1928)

Historic Range:
Circumglobal in tropical and temperate seas and oceans

Atlantic, Pacific, and Indian Oceans. In the Atlantic, they occur as far north as England.

They are called green turtles because of the color of the flesh. Chelonia mydas are one of the largest turtles ranging from 71 to 153 centimeters. They can weigh up to 205 kilograms. They have limbs that are paddle-like, which are used to swim. Their heads seem small compared to their body size. Males are larger than females and the tail is longer, extending well beyond the shell. The carapace can be olive to brown, or sometimes black, depending on the geographic location of the species. Green turtles cannot pull their heads inside of their shells. There are two sub-species which include Chelonia mydas mydas and Chelonia mydas agassizii. The common name for Chelonia mydas mydas is the Atlantic green turtle, which lives in the Atlantic ocean and has been see off the shores of Europe and North America. Chelonia mydas agassizii, or Eastern Pacific green turtle and sometimes black sea turtle because of its dark colored carapace, has been see off the coasts of Alaska, through California, and to Chile. Some features that distinguish C. m. agassizii from C. m. mydas are that the shell of C. m. agassizii is higher, the shell is narrower, the marginals are more constricted over the hind legs, and the postcentral lamina are longer relative to their width (Ernst 1994). The Pacific and Atlantic populations have been separated for millions of years.

Range mass: 0 to 0 kg.

Average mass: 205 kg.

Length: 122 cm

Weight: 200000 grams

To 153 cm carapace length

Differs from the hawksbill in having one rather than two pairs of prefrontals and carapace scutes that do not overlap. Differs from the loggerhead and the ridleys in having the first costal not in contact with the nuchal.

The Niger Coastal Delta is an enormous classic distributary system located in West Africa, which stretches more than 300 kilometres wide and serves to capture most of the heavy silt load carried by the Niger River. The peak discharge at the mouth is around 21,800 cubic metres per second in mid-October. The Niger Delta coastal region is arguably the wettest place in Africa with an annual rainfall of over 4000 millimetres. Vertebrate species richness is relatively high in the Niger Delta, although vertebrate endemism is quite low. The Niger Delta swamp forests occupy the entire upper coastal delta. Historically the most important timber species of the inner delta was the Abura (Fleroya ledermannii), a Vulnerable swamp-loving West African tree, which has been reduced below populations viable for timber harvesting in the Niger Delta due to recent over-harvesting of this species as well as general habitat destruction of the delta due to the expanding human population here. Other plants prominent in the inner delta flood forest are: the Azobe tree (Lophira alata), the Okhuen tree (Ricinodendron heudelotii ), the Bitter Bark Tree (Sacoglottis gabonensis), the Rough-barked Flat-top Tree (Albizia adianthifolia), and Pycnanthus angolensis. Also present in its native range is the African Oil Palm (Elaeis guineensis).

Five threatened marine turtle species are found in the mangroves of the lower coastal delta: Leatherback Sea Turtle (Dermochelys coriacea, EN), Loggerhead Sea Turtle (Caretta caretta, EN), Olive Ridley Turtle (Lepidochelys olivacea, EN), Hawksbill Sea Turtle (Eretmochelys imbricata, CR), and Green Turtle (Chelonia mydas, EN).

There are a number of notable mammals present in the inner coastal delta, including the Near Threatened Olive Colobus (Procolobus verus) that is restricted to coastal forests of West Africa and is found here in the inner coastal Niger Delta. Also found here is the restricted distribution Mona Monkey (Cercopithecus mona), a primate often associated with rivers. Also occurring here is the limited range Black Duiker (Cephalophus niger), a near-endemic to the Niger River Basin. In addition, the Endangered Chimpanzee (Pan troglodytes) is found in the Niger Delta. The near-endemic White-cheeked Guenon (Cercopithecus erythrogaster, VU) is found in the inner delta. The Critically Endangered Niger Delta Red Colubus (Procolobus pennantii ssp. epieni), which primate is endemic to the Niger Delta is also found in the inner delta. 

Some of the reptiles found in the upper coastal Niger Delta are the African Banded Snake (Chamaelycus fasciatus); the West African Dwarf Crocodile (Osteolaemus tetraspis, VU); the African Slender-snouted Crocodile (Mecistops cataphractus); the Benin Agama (Agama gracilimembris); the Owen's Chameleon (Chamaeleo oweni); the limited range Marsh Snake (Natriciteres fuliginoides); the rather widely distributed Black-line Green Snake (Hapsidophrys lineatus); Cross's Beaked Snake (Rhinotyphlops crossii), an endemic to the Niger Basin as a whole; Morquard's File Snake (Mehelya guirali); the Dull Purple-glossed Snake (Amblyodipsas unicolor); the Rhinoceros Viper (Bitis nasicornis). In addition several of the reptiles found in the outer delta are found within this inner coastal delta area.

Other reptiles found in the outer NIger Delta are the Nile Crocodile (Crocodylus niloticus), African Softshell Turtle (Trionyx triunguis), African Rock Python (Python sebae), Boomslang Snake (Dispholidus typus), Cabinda Lidless Skink (Panaspis cabindae), Neon Blue Tailed Tree Lizard (Holaspis guentheri), Fischer's Dwarf Gecko (Lygodactylus fischeri), Richardson's Leaf-Toed Gecko (Hemidactylus richardsonii), Spotted Night Adder (Causus maculatus), Tholloni's African Water Snake (Grayia tholloni), Smith's African Water Snake (Grayia smythii), Small-eyed File Snake (Mehelya stenophthalmus), Western Forest File Snake (Mehelya poensis), Western Crowned Snake (Meizodon coronatus), Western Green Snake (Philothamnus irregularis), Variable Green Snake (Philothamnus heterodermus), Slender Burrowing Asp (Atractaspis aterrima), Forest Cobra (Naja melanoleuca), Rough-scaled Bush Viper (Atheris squamigera), and Nile Monitor (Varanus niloticus).

There are a limited number of amphibians in the inner coastal delta including the Marble-legged Frog (Hylarana galamensis). At the extreme eastern edge of the upper delta is a part of the lower Niger and Cross River watersheds that drains the Cross-Sanaka Bioko coastal forests, where the near endemic anuran Cameroon Slippery Frog (Conraua robusta) occurs.

Habitat and Ecology

Systems

• Terrestrial
• Marine

Green sea turtles live in tropical waters all over the world. The only time they emerge from the water is when they are nesting. The only time males are not at sea is when they were first born. C. m. agassizii are sometimes found with seals and albatrosses basking on the beach (Pritchard 1967). When it is time to mate they migrate from several hundred to over a thousand miles across the ocean to where they hatched. Female green turtles use the same beaches to nest as their mothers and grandmothers.

Aquatic Biomes: coastal

Depth range based on 8054 specimens in 1 taxon.
Water temperature and chemistry ranges based on 4162 samples.

Environmental ranges
  Depth range (m): 0 - 3250
  Temperature range (°C): 2.498 - 29.497
  Nitrate (umol/L): 0.015 - 26.152
  Salinity (PPS): 22.907 - 37.161
  Oxygen (ml/l): 2.556 - 6.419
  Phosphate (umol/l): 0.033 - 1.673
  Silicate (umol/l): 0.769 - 27.080

Graphical representation

Depth range (m): 0 - 3250

Temperature range (°C): 2.498 - 29.497

Nitrate (umol/L): 0.015 - 26.152

Salinity (PPS): 22.907 - 37.161

Oxygen (ml/l): 2.556 - 6.419

Phosphate (umol/l): 0.033 - 1.673

Silicate (umol/l): 0.769 - 27.080
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Warm marine waters. Frequently segrass beds, which by nature are in fairly shallow, sandy, inshore habitats. Often near wadi deltas (In the Red Sea), where the fringing reef is broken and suitable sandy substrate in shallow waters is available. Generally, the availability of suitable seagrass beds is limited in the Egyption Red Sea, and apparently so in the Mediterranean as well, given the small number of records in Egyption territory. Nesting in the Red Sea has been recorded in the months of June and July. Sexual maturity reached between 12 and 50 years, depending on location and nutritional history.

Comments: Feeding occurs in shallow, low-energy waters with abundant submerged vegetation, and also in convergence zones in the open ocean (NMFS and USFWS 2007). Migrations may traverse open seas. Adults are tropical in distribution, whereas juveniles range into temperate waters (e.g., see Morreale and Standora, no date). Hatchlings often float in masses of marine macroalgae (e.g., Sargassum) in convergence zones. Coral reefs and rocky outcrops near feeding pastures often are used as resting areas. Inactive individuals may rest on the bottom in winter in the northern Gulf of California. Basking on beaches occurs in some areas (e.g., Hawaii).

Nesting occurs on beaches, usually on islands but also on the mainland. Sand may be coarse to fine, has little organic content; physical characteristics vary greatly in different regions. Most nesting occurs on high energy beaches with deep sand. At least in some regions, individuals generally nest at same beach (apparently the natal beach, Meylan et al. 1990, Allard et al. 1994) in successive nestings, though individuals sometimes change to a different nesting beach within a single nesting season (has switched to beach up to several hundred kilometers away) (see Eckert et al. 1989). Beach development and illumination often make beaches unsuitable for successful nesting.

 Adults inhabit shallow tropical feeding grounds that are often seagrass meadows, migrating from these areas to their nesting beaches not in the UK.

Young Green turtles are pelagic, coming to shallow waters when they've grown to around 20-25 cm. Juveniles and adults prefer shallow waters and reef areas.

Adults inhabit shallow feeding grounds that are often seagrass meadows, migrating from these areas to their nesting beaches (6). Once juveniles hatch, they spend an unknown number of years in the open ocean (6).

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.

Adults migrate up to about 3,000 km between nesting beaches and feeding areas (e.g., between Ascension Island and the South American coast). See Balazs (1982) for a map of documented migrations between the major nesting area in Hawaii (French Frigate Shoals) and foraging areas elsewhere in the Hawaiian Islands. See Morreale and Standora (no date) for information on movements along the east coast of the United States.

Seminoff et al. (2002) documented migration between nesting area on the coast of Michoacan (Mexico; January 2000) and a feeding ground on the Sonoran coast of the Gulf of California (Mexico; September 2000).

See Mortimer and Porter (1989) for information on internesting movements at Ascension Island.

Neonates migrate far from natal beaches to foraging areas and return to natal beach to breed/nest up to 40+ years later.

Green turtles are mostly herbivorous. They spend most of their time feeding on algae in the sea and the grass that grow in shallow waters. As juveniles, they eat plants and other organisms such as: jellyfish, crabs, sponges, snails, and worms. As adults, they are strictly herbivorous (Ernst 1994).

Comments: Diet includes"seagrass," macroalgae and other marine vegetation, and various invertebrates such as mollusks, sponges, crustaceans, and jellyfish.

Adults are mostly herbivorous, consuming sea grasses and algae. They will also take jellyfish, salps, and sponges. Young, while in the pelagic stage, are carnivorous.

When young, green sea turtles eat plants, jellyfish, crabs, sponges, snails, and worms. Because it eats both plants and animals, it is an omnivore when young. But when it becomes an adult, it eats only plants—seagrass, seaweeds and different types of algae—so it is an herbivore.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 to >300

Comments: This species is represented by a large number of nesting occurrences (more than 150 major and minor nesting areas in more than 80 nations worldwide).

100,000 to >1,000,000 individuals

Comments: At 46 nesting areas worldwide, representing most but not all of the global population, the latest data indicate that approximately 109,000-151,000 females nest each year (NMFS and USFWS 2007). Assuming an average remigration interval of 3 years, this indicates an adult female population size of roughly 327,000-453,000. Assuming an equal number of adult males yields 654,000-906,000 adults for this subset of the global population.

Eggs and hatchlings typically incur high mortality from various terrestrial and aquatic predators, including both vertebrates and invertebrates (e.g., crabs). Many nests are destroyed by tidal inundation and erosion. In Costa Rica, annual survivorship of adult females was 0.61; in various areas egg survivorship was 0.40-0.86 (see Iverson [1991] for a compilation of survivorship data). Humans are the most important predators on adults. See Witherington and Ehrhart (1989) for information on cold stunning in Florida.

Herbivorous, feeding largely on marine grasses and algae when adult; young carnivorous, pelagic.

Comments: Turtles in the northern Gulf of California overwinter in a dormant condition. Nesting occurs generally at night. In Hawaii, green sea turtles may bask on beaches mid-morning to mid-afternoon, especially after a period of rainy weather (Whittow and Balazs 1982).

Average lifespan
Status: captivity: 75 years.

Maximum longevity: 75 years Observations: Some anecdotal evidence suggests these animals may live beyond a century but their record longevity is largely unknown. The age at sexual maturity is also a subject of debate and could be over 20 years (John Behler and F. King 1979).

Males and females mature between 10 and 24 years. The breeding season depends on the latitude. Internal fertilization takes place when the male and female copulate. This is the only time there is vocalization. Like many species, there is male competition. One male may try to bite another male who is copulating with a female. Mating occurs underwater or on the surface about one kilometer from the shore. Sometimes the female will retain enough sperm to nest several times that year. Nesting occurs every three to six years. When the female is ready to lay her eggs, she leaves the water, crawls onto the sand and starts digging for hour and hours until her flippers will not allow her to dig deeper. She then lays 100 to 200 eggs. This group of eggs is called a clutch. She covers them with sand to protect them from the sun, heat, and predators. Pacific green turtles lay fewer eggs than Atlantic green turtles. The gestation period is 40 to 72 days, depending on the location.

Average gestation period: 59 days.

Average number of offspring: 150.

Average age at sexual or reproductive maturity (male)
Sex: male: 3650 days.

Average age at sexual or reproductive maturity (female)
Sex: female: 3650 days.

Individual reproductive females lay 1-8 clutches per season, averaging about 90-140 eggs, at about two-week intervals usually every 2-5 years. Nesting occurs March-October in Caribbean-Gulf of Mexico region, with peak in May-June; nests in Florida May-September (Ehrhart and Witherington 1992). Nesting encompasses April-October, with a peak between mid-June and early August, in Hawaii (Niethammer et al. 1997). Eggs hatch usually in 1.5-3 months. Hatchlings emerged between early July and late December (peak mid-August to early October) in Hawaii (Niethammer et al. 1997). Females mature probably at an average age of 27 years in Florida, but growth rates and hence age of maturity may vary greatly (from perhaps fewer than 20 years to 40+ years) throughout the range (slower growth in Australia, Hawaii, and Galapagos than in Florida and West Indies region).

Mating and nesting takes place in the tropics from March to October in the Atlantic and Caribbean. Several males will attempt to mate with a single female. Females nest on islands and mainland beaches, and show a high degree of nest site fidelity. Nesting takes place at night. Approximately 112 eggs are laid in each clutch, and a female will clutch up to 3 times in a reproductive season. She then will not clutch again for another 2-3 years. The nesting process takes 2-3 hours.

Year Assessed

Assessor/s

Reviewer/s

Contributor/s

Justification

History

• 1996
  Endangered
• 1996
  Endangered
• 1994
  Endangered
  (Groombridge 1994)
• 1990
  Endangered
  (IUCN 1990)
• 1988
  Endangered
  (IUCN Conservation Monitoring Centre 1988)
• 1986
  Endangered
  (IUCN Conservation Monitoring Centre 1986)
• 1982
  Endangered

Green turtles are an endangered species because they have so many predators--including humans. Even though a female can lay over 200 eggs in on clutch, some will not hatch, and many will be eaten. Even if they do hatch, they get eaten on their way to the water, and in the water. So only a few will survive if any. If the they do survive, they can live to be over 100 years old. Sometimes eggs are laid on a public beach. When this happens conservationists come and move them to a safer place. In the United States, green turtles are protected by the Endangered Species Act.

US Federal List: endangered

CITES: appendix i

IUCN Red List of Threatened Species: endangered

Uncommon, localized and declin­ing. Facing a variety of threats in Egypt, most importantly as a by-catch of commercial fishing vessels. The species along with other marine tur­tles are consumed in some Egyptian coastal cities. Loss of nesting beaches is also a problem particularly in the Red Sea.

Endangered

United States

Rounded National Status Rank: N3B,N3N : N3B: Vulnerable - Breeding, N3N: Vulnerable - Nonbreeding

Rounded Global Status Rank: G3 - Vulnerable

Reasons: Distributed worldwide in warm oceans; exploited heavily for meat and eggs and as a component of other products; nesting and feeding habitats are being destroyed or degraded by pollution and development; large decline over the long term, more recently possibly stable or increasing in some areas.

Environmental Specificity: Very narrow to narrow.

Other Considerations: Individuals migrate up to 2,000 km between nesting beaches and feeding areas. Hence local populations may experience negative impacts from distant threats.

Classified as Endangered (EN) on the IUCN Red List 2007 (1). Listed on Appendix I of CITES (3) and Appendices I and II of the Convention on Migratory Species (CMS or Bonn Convention) (4).

Population Trend

Major Threats

Though green sea turtles have lived on Earth for 150 million years—since before the time of dinosaurs—they are now endangered and their population is decreasing! Many people like to eat them and hunt them for shells and leather. Sometimes they are accidentally caught and killed by the fishing industry that is trying to catch other fish. Green sea turtles are on the endangered species list, and there are many projects to try and protect them. One is the Sea Turtle Restoration Project.

Green turtles are overharvested in many areas for both their meat and eggs (8). The meat is highly prized and the cartilage underneath the plastron (known as 'calipee') is used in the production of turtle soup (2). In addition, as with other marine turtles, these reptiles are accidentally caught in bycatch of the fishing industry (8). One of the most worrying threats in recent years has been an increase in fibropapillomas; fibrous tumours that can grow on almost any part of a turtles body, impeding movement or sight, and often leading to death (6). Very little is known about the disease, which is believed to be a virus, and its prominence varies amongst different populations, although there may be a link with coastal areas of heavy human use (9).

Restoration Potential: Pattern of nesting on natal beach may inhibit natural recolonization of breeding sites of decimated populations.

Preserve Selection and Design Considerations: Local foraging populations may consist of individuals from widely separated nesting populations. For example, mtDNA data indicate that a foraging population of juveniles from Hutchinson Island, Florida, consisted of individuals from Costa Rica, United States and Mexico, and Aves Island (Venezuela and Surinam; another population of juveniles from the Bahamas represented Costa Rica, United States and Mexico, Aves Island and Suriname, and Ascension Island and Guinea Bissau (Bass and Witzell 2000). Thus the success of preserves for foraging juveniles may depend on cooperative international management (Bass and Witzell 2000).

Management Requirements: Frazer (1992) emphasized the primary need for clean and productive marine and coastal environments; installation of turtle excluder devices in shrimp trawl nets and use of low pressure sodium lighting on beaches were suggested as appropriate sea turtle conservation technologies, whereas headstarting, captive breeding, and hatcheries were regarded as ineffective at best. "Head-starting" and broad-scale nest translocation remain unproven as effective management measures (Ehrhart and Witherington 1992). See Bjorndal (1982) for several papers containing management and research recommendations and discussion of conservation issues.

See NMFS (Federal Register, 19 December 1996, pp. 66933-66947) for recent amendments to regulations pertaining to the use of turtle excluder devices along the Gulf and Atlantic coasts of the southeastern U.S. See NMFS (1993) for recent shrimp trawling regulations for an area off the coast of North Carolina (allow tow-time limits as an interim alternative to the use of turtle excluder devices).

If beach lighting cannot be eliminated, low pressure sodium vapor lights may be the least disruptive to nesting turtles (Witherington 1992).

A recovery plan is available; see Marine Turtle Recovery Team (1984). See also recovery plans for U.S. Pacific and east Pacific populations (NMFS 1998) .

[Move to GPROTNEED: Ehrhart and Witherington (1992) emphasized the need to protect nesting areas in southern Brevard and northern Indian River counties in southeastern Florida.]

Biological Research Needs: Better information is needed on demography, migrations, and developmental requirements.

Needs: Foraging, developmental, and nesting habitat need protection from from any type of human activity. Purchase of turtle products should be discouraged.

See "Recovery plan for U.S. Pacific populations of the green turtle (Chelonia mydas)" and "Recovery plan for U.S. Pacific populations of the east Pacific green turtle (Chelonia mydas)."

The green turtle is protected form international trade by its listing on Appendix I of the Convention on International Trade in Endangered Species (CITES) (3). A number of conservation projects around the world work to protect nesting areas from disturbance (6). The increasing prevalence of fibropapillomas is an extremely worrying phenomenon and scientists are working hard to understand this disease.

According to "The Official World Wildlife Fund Guide to Endangered Species of North America," in some areas of the world such as the Caribbean, Mexico, and South America, green sea turtles are an important source of food for humans. They are captured and their meat is used for turtle soup (Behler, 1998).

Comments: Adults and eggs are harvested for human consumption in many areas, also for skins and oil for the leather and cosmetics trade. See Mack et al. (1982) for information on commercial exploitation. See Luxmoore and Canin (1985) for information on international trade in shell in the late 1970s and early 1980s.