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Beached adult on black sand beach, Hawaii, Hawaii |
Captive, Maui, Hawaii |
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Aquarium captives, Maui, Hawaii |
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Captive rescued adult from the Gulf of Mexico.
Sea Turtle Rescue Center, Sea Turtle Inc., South Padre Island, Texas |
Swimming adult, Hawaii, Hawaii |
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Captive adult "Black Sea Turtles" in rehabilitation, from the Bay of Cortez.
Sea Turtle Preservation Center, Bahia de los Angeles, Baja California, Mexico
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Stuffed adult, Santa Barbara Museum of Natural History |
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Sign at Maui Aquarium |
Pacific Ocean habitat, San Mateo County |
Habitat in California, the Pacific ocean
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| Description |
| Size |
| Adults are 30 - 60+ inches in shell length (75 - 152+ cm). (Stebbins 2003) |
| Appearance |
A large marine turtle with powerful paddlelike forelimbs and a broad, low, smooth, heart-shaped, unserrated carapace with 4 costal shields on each side. The first costal shield does not touch the nuchal. The carapace is greenish, olive, brown, gray, or black, sometimes with a mottled or radiating pattern, especially on younger turtles. The name of this turtle derives from its green fat, not its external coloration. There is a single pair of prefrontals, the large scales between the upper eyelids. The plastron is pale yellow or whitish and unmarked. The head plates are olive with yellow edges.
This species typically weighs from 120 - 200 lbs., but some have weighed over 600 lbs.
Males have a longer and narrower carapace than females, a long prehensile tail with a flat nail at the tip, and an enlarged curved claw on the front flipper. A female's tail barely reaches the rim of the shell.
Young turtles have a vertebral keel and a pair of keels on the plastron. Their flippers are edged with white. |
| Behavior and Natural History |
Aquatic, living in the ocean and rarely coming onto land, though this species is more prone to bask onshore than other Sea Turtles. Often found far out at sea, especially during migration to and from breeding sites.
Diurnal. Forages in daylight. Basks on isolated shores, or while floating at the surface where solar heat can be absorbed through the dark carapace.
Hatchlings spend a year or more out at sea. This period has been called the "lost years" because researchers did not know where the turtles went or what they did during this period. In 2007, a study has determined that they spend these years out in the open ocean, feeding carnivorously on jellyfish and other animals. After this period, they appear in shallow waters where they feed on vegetation until reaching maturity.
Adult turtles have few predators in the open ocean. Humans, tiger sharks, and groupers are a few. |
| Diet |
| Omnivorous. Eats seaweed, algae, and invertebrates including sponges and jellyfish. Juveniles are more carnivorous than adults. |
| Reproduction |
Adults take from 19 - 24 years to reach sexual maturity. After maturing, they return to the beach where they hatched [which might involve a long migration of as far as 2,000 miles (3,200 km)]. Nesting sites are communal and re-used each season. Most California turtles probably hatched at nesting sites on the Pacific Coast of the Americas - Panama, Costa Rica, Nicaragua, Guatemala, El Salvador, Michoacan, Chiapas, and Baja California.
Mating takes place in shallow water off the nesting beach. In the eastern Pacific, breeding occurs any time between February and January, with peak periods depending on location - April to June in Hawaii. Most females breed every third year, with others breeding every 2 - 4 years. After a female turtle mates, she crawls at night onto the flat or gradually-sloped sandy nesting beach and finds a spot where the coarseness and moisture content of the sand arejust right for the eggs to survive. There she digs a nest cavity with her hind feet, lays her eggs, then covers them up. After laying her eggs, the female turtle crawls back into the sea.
A female will lay from 1 - 7 clutches of eggs per nesting season. The average size of a clutch is 100 - 120 eggs.
Eggs in the nest are in constant danger of predation by crabs, beetles, maggots, ants, vultures, shorebirds, seabirds, and various mammals such as skunks, pigs, opossums, mongooses, and humans. After about 2 months, the eggs hatch, and the hatchlings struggle to dig themselves out of the sand. They emerge at night and crawl towards the ocean, again suffering attacks from many predators, including crabs, ants, snakes, vultures, ravens, gulls and other ocean-going birds, and mammals including feral cats and dogs, skunks, and peccaries. After entering the water, they continue to be under attack, by dolphin fish, groupers and other fish, and bottlenosed dolphins. Few hatchlings ever survive the first year. |
| Range |
Ranges all over the world in tropical waters, moving into temperate zones in the summer.
Recorded along the pacific coasts of the Americas from Alaska to Chile. Common as far north as San Quintin Bay in Baja California, but uncommon along the California coast.
From November to April, a small population of Green Sea Turtles lives in the warm water effluent channel of the San Diego Gas & Electric power plant in San Diego Bay. (Stebbins 2003) Another small colony has taken up residence in the warm-water discharge from a Long Beach power plant where it flows into the San Gabriel River. Green Sea Turtles are occasionally seen elsewhere along the California Coast, usually in El Niño years when the ocean temperature is higher than normal. Locations where Green Sea Turtles have been seen in California waters include San Francisco, San Clemente Island, Newport Beach in Los Angeles County, San Diego Bay, Santa Ynez in Santa Barbara County, and Seal Cove and Año Nuevo State Reserve in San Mateo County. |
| Habitat |
| Inhabits the shallow waters of lagoons, bays, estuaries, mangroves, eelgrass and seaweed beds. Prefers areas with abundant aquatic vegetation, such as pastures of sea grasses and algae, in shallow, protected water. |
| Taxonomic Notes |
| Green Sea Turtle taxonomy is controversial. Some researchers consider the Pacific Ocean population of Chelonia mydas to be a separate species, Chelonia agassizii. Others consider it a separate subspecies, Chelonia mydas agassizii. Some refer to turtles found in the eastern Pacific (which would be our area) as C. agassizii, the Black Sea Turtle. You can read a more detailed summary of some of the issues in C. mydas taxonomy at Seaturtle.org. |
| Conservation Issues (Conservation Status) |
Seriously threatened.
The worldwide population of this sea turtle has declined aproximately 90 percent in the last 50 years. (Stebbins 2003)
A major cause of the decline is overexploitation of the turtles for meat and for their eggs by humans. The Green Seaturtle is of great economic importance worldwide, especially in many third world nations where it is an important source of protein. The turtle soup industry has also supported commercial fisheries since the 17th century. At one time there was even a commercial turtle processing industry in Florida.
Other causes for the decline of sea turtles include the development and degradation of nesting beaches, degradation of feeding habitats, entanglement of turtles in fishing nets, including discarded nets, and ingestion of plastic garbage, especially plastic grocery bags (which look like jellyfish floating on the surface) and offshore boats moving so quickly that turtles are not able to move out of the way fast enought to avoid being killed or injured. Some authorities also question whether humans handling nesting females and doing research on nesting beaches is stressing the turtles and lowering reproduction and survivorship. |
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Taxonomy |
| Family |
Cheloniidae |
Sea Turtles |
| Genus |
Chelonia |
Green Sea Turtles |
Species
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mydas |
Green Sea Turtle |
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Original Description |
Chelonia mydas - (Linnaeus, 1758) - Syst. Nat., 10th ed., Vol. 1, p. 197
from Original Description Citations for the Reptiles and Amphibians of North America © Ellin Beltz
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Meaning of the Scientific Name |
Chelonia - Greek - chelone - tortoise
mydas - Greek - mydos - wetness, dampness - refers to its aquatic habitat
from Scientific and Common Names of the Reptiles and Amphibians of North America - Explained © Ellin Beltz
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Alternate Names |
Green Turtle
Black Sea Turtle
Eastern Pacific Green Sea Turtle
Chelonia agassizii
Chelonia mydas agassizii -Pacific Green Sea Turtle
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Related or Similar California Turtles |
C. caretta - Loggerhead Sea Turtle
E. i. bissa - Pacific Hawksbill Sea Turtle
L. olivacea - Olive Ridley Sea Turtle
D. coriacea -Leatherback Sea Turtle
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More Information and References |
NatureServe Explorer
California Department of Fish and Game
Stebbins, Robert C. A Field Guide to Western Reptiles and Amphibians. 3rd Edition. Houghton Mifflin Company, 2003.
Behler, John L., & F. Wayne King. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, 1992.
Carr, Archie. Handbook of Turtles: The Turtles of the United States, Canada, and Baja California. Cornell University Press, 1969.
Ernst, Carl H., Roger W. Barbour, & Jeffrey E. Lovich. Turtles of the United States and Canada. Smithsonian Institution 1994.
Lemm, Jeffrey. Field Guide to Amphibians and Reptiles of the San Diego Region (California Natural History Guides). University of California Press, 2006.
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The following status listings come from the Special Animals List which is published several times each year by the California Department of Fish and Game.
This turtle is listed as the Green Turtle.
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Organization
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Status Listing
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| U.S. Endangered Species Act (ESA) |
FT |
Threatened |
| California Endangered Species Act (CESA) |
None |
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| California Department of Fish and Game |
None |
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| Bureau of Land Management |
None |
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| USDA Forest Service |
None |
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| Natureserve Global Conservation Status Ranks |
G3 |
Vulnerable |
World Conservation Union - IUCN Red List
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IUCN:EN |
Endangered |
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