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Species in this Guide: 165
Marine Building
Created by: Education Department
Green Turtle  Chelonia mydas         View on EOL
Overview

Taxon Biology
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.Recorder: Beth Sanzenbacher, Recorder: Audrey Aronowsky  Source: WhyReef   CC License: by

General Description
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).Source: Wildscreen   CC License: by-nc-sa

Description
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.Editor: Dr Harvey Tyler-Walters, Author: Rebecca Harris  Source:  The Marine Biological Association of the United Kingdom   CC License: by-nc-sa

Distribution
Green turtles are found in tropical waters around the globe, particularly associated with the coastline (8).Source: Wildscreen   CC License: by-nc-sa

Conservation

Conservation Status
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).Source: Wildscreen   CC License: by-nc-sa

Management
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.Source: Wildscreen   CC License: by-nc-sa

Threats
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).Source: Wildscreen   CC License: by-nc-sa

Trends
Population Trend
Decreasing
Author: Seminoff, J.A., Compiler: Seminoff, J.A. (Southwest Fisheries Science Center, U.S.)  Source: International Union for Conservation of Nature and Natural Resources   CC License: by-nc-sa

Physical Description

Diagnostic Description
Es una especie de IMAGEDB.GET_BFILE_IMAGE?p_imageId=11077&p_imageResolutionId=2">(ver">http://attila.inbio.ac.cr:7777/pls/portal30IMAGEDB.GET_BFILE_IMAGE?p_imageId=11077&p_imageResolutionId=2">(ver magen)mediano tamaño que alcanza los 1.530 mm. de largo. Presenta un par de escamas prefrontales en la cabeza y la mandíbula inferior posee un borde filoso aserrado. El caparazón tiene forma de corazón visto dorsalmente, es ancho, bajo y aserrado posteriormente; la quilla vertebral está ausente. Tiene 4 pares de escamas pleurales, las primeras no tocan la cervical. El puente presenta 4 escamas inframarginales sin poros. El plastrón es blanco, su fórmula es abd>an>pect>hum>intergul.

El color de la piel varía de café a gris y negro y muchas de las escamas de la cabeza pueden tener márgenes amarillas IMAGEDB.GET_BFILE_IMAGE?p_imageId=11078&p_imageResolutionId=2">(ver">http://attila.inbio.ac.cr:7777/pls/portal30IMAGEDB.GET_BFILE_IMAGE?p_imageId=11078&p_imageResolutionId=2">(ver imagen). La superficie interna de la mandíbula superior tiene proyecciones verticales bien desarrolladas. Hay 4 escamas post-oculares presentes. Las superficies superiores del caparazón son de color café. No tiene indentaciones entre las escamas marginales del borde del caparazón, que se localizan sobre los miembros.Author: Federico Munoz Chacon  Source: INBio, Costa Rica   CC License: by-nc-sa

Morphology

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.

Other Physical Features: Ectothermic; Bilateral symmetry
Editor: Tanya Dewey, Animal Diversity Web, University of Michigan Museum of Zoology, Author: Janel Crite, University of Michigan  Source: The Regents of the University of Michigan and its licensors   CC License: by-nc-sa

Size
To 153 cm carapace lengthSource: Gulf of Maine - CoML   CC License: by-nc-sa

Ecology

Associations
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.Recorder: Beth Sanzenbacher, Recorder: Audrey Aronowsky  Source: WhyReef   CC License: by

Habitat
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).Source: Wildscreen   CC License: by-nc-sa

Population Biology
La población de Costa Rica es quizá la mejor conocida de toda la especie. Se alimenta extensivamente en los bancos de zacate marino Thalassia a lo largo de la costa caribeña nicaraguense y regresa a las costas arenosas del norte de Costa Rica, Tortuguero específicamente, para anidar.Author: Federico Munoz Chacon  Source: INBio, Costa Rica   CC License: by-nc-sa

Trophic Strategy
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.Source: Gulf of Maine - CoML   CC License: by-nc-sa

Life History and Behavior

Behavior

Baby turtles use their egg tooth when they hatch to break the shell of the egg. Females lay so many eggs because the chance for their survival is very low. Sometimes animals such as raccoons, foxes, coyotes, ants, and even people will dig up the eggs and eat them. But if the eggs are successful, when they hatch they start moving their flippers. When they do this, the sand starts to fall below them, pushing them up out of the hole so they can start making their way to the sea. As soon as they get to the sea, they start to drift off. They spend a few years floating at sea eating plankton at the surface. During this time, their shell is soft and they are very subject to predation by fish. After a few years of eating plankton, they move to shallow waters to feed on sea grasses.

To avoid predation, they dive and swim away. Young green turtles that have just hatched are the most vulnerable. They may get eaten from the time they hatch, crossing the sand on their way to the ocean, and during the first couple of years at sea. Predators in the sand include ghost crabs, ants, snakes, gulls, opossums, rats, and vultures. There are many more in the water such as sharks, dolphin fish, kingfish, needlefish, and bottle-nosed dolphins (Ernst 1994).

Key Behaviors: motile
Editor: Tanya Dewey, Animal Diversity Web, University of Michigan Museum of Zoology, Author: Janel Crite, University of Michigan  Source: The Regents of the University of Michigan and its licensors   CC License: by-nc-sa

Cyclicity
La época de anidación comienza en junio y termina al final de setiembre.Author: Federico Munoz Chacon  Source: INBio, Costa Rica   CC License: by-nc-sa

Life Expectancy
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).Editor: de Magalhaes, J. P.  Source: Joao Pedro de Magalhaes   CC License: by

Reproduction
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.Source: Gulf of Maine - CoML   CC License: by-nc-sa

Evolution and Systematics

Evolution
Shell alters buoyancy: green turtle

The shell of some sea turtles allows for different levels of buoyancy for juveniles and adults by changing shape.


"Sea turtles sometimes swim on the surface; Jeanette Wyneken tells me that the flared, V-shaped bottom is characteristic of buoyant baby sea turtles, which are obligatory surface swimmers. With maturity and the shift to submerged swimming, the hull shape changes to one more characteristic of submarines." (Vogel 2003:116)
Learn more about this functional adaptation.Editor: The Biomimicry Institute  Source: The Biomimicry Institute   CC License: by-nc

Molecular Biology and Genetics

Molecular Biology
Barcode of Life Data Systems (BOLDS) Stats
Public Records: 9
Species: 32
Species With Barcodes: 1

Compiler: Sujeevan Ratnasingham, Compiler: Paul D.N. Hebert  Source: Barcode of Life Data Systems   CC License: by

Relevance to Humans and Ecosystems

Benefits
Tanto su carne como sus huevos son consumidos ampliamente, a lo largo de su distribución.Author: Federico Munoz Chacon  Source: INBio, Costa Rica   CC License: by-nc-sa

Show/Hide iNaturalist Observations Map for this species. Source: iNaturalist