Chelonia mydasGreen Turtle

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Geographic Range

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. (Ernst, et al., 1994)

Habitat

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.

Physical Description

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
    0.00 to 0.00 lb
  • Average mass
    205 kg
    451.54 lb

Reproduction

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.

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • Average number of offspring
    150
    AnAge
  • Average gestation period
    59 days
    AnAge
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    3650 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    3650 days
    AnAge

Lifespan/Longevity

  • Average lifespan
    Status: captivity
    75 years
    AnAge

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).

Food Habits

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).

Economic Importance for Humans: Positive

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).

Conservation Status

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.

Contributors

Janel Crite (author), University of Michigan-Ann Arbor, Tanya Dewey (editor), Animal Diversity Web.

Glossary

Atlantic Ocean

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

World Map

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

coastal

the nearshore aquatic habitats near a coast, or shoreline.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

References

1990. The Official World Wildlife Fund Guide to Endangered Species of North America. Vol. 2. Washington, D.C.: Beacham Publishing, Inc..

Behler, J. 1998. National Audbon Society Field Guide to North American Reptiles and Amphibians. New York: Alred a. Knopf,Inc. Chancileer Press.

Ernst, C., R. Barbour, J. Lovich. 1994. TURTLES of the United States and Canada. Washington and London: Smithsonian Institution.

Pritchard, P. 1967. Living Turtles of the World. New Jersey: T.F.H. Publications.