The Green turtle is also known as the Green Sea Turtle and is found in the Atlantic, the Pacific Ocean, the Indian Ocean, the Mediterranean and the Black Sea. Its scientific name is Chelonia mydas and it is the only species found in the genus Chelonia in the family Chelonioidea. Other commonly used names for the Green turtle are Tortuga verde, Tortuga blanca, Tortue verte, Tortue comestible and Tortue franche. 

There exists two regocnized subspecies of Green turtle: Chelonia mydas mydas and Chelonia mydas agassizii. Chelonia mydas mydas is also known as the Atlantic green turtle, while Chelonia mydas agassizii is called Eastern Pacific green turtle or Black sea turtle. It is not found in the Black Sea; the name Black sea turtle is derived from the dark coloration of the carapace. You can distinguish Chelonia mydas agassizii from Chelonia mydas mydas by looking at its body shape. Chelonia mydas agassizii have a higher and more narrow shell, the marinals are more constricted over the animals hind legs and the postcentral lamina are longer compared to their width. 

Despite its name, the Green turtle does not have a green carapace; it is instead olive coloured, brown or black depending on geographic location. The name Green turtle is instead derived from the colour of the body fat; adult Green turtles consume vast amounts of algae that turns their body fat green. Adult Green turtles are herbivorous and feed chiefly on algae. When they venture into shallow waters, they may eat sea grass. Young Green turtles are not strict herbivores and will often supplement their plant diet with crabs, jellyfish, worms, snails and sponges.

The Green turtle is one of the biggest hard-shelled turtles and adults will range in size from just above 70 centimetres to over 150 centimetres. A Green turtle can weigh over 200 kilograms and males grow larger than females. The male Green turtle will also have a longer tail that protrudes behind the shell. Both sexes have paddle-shaped limps that make them skilled swimmers. Green turtles can not protect their head by retracting it into the shell. 

As mentioned above, the Green turtle as a circumglobal distribution. It lives chiefly in tropical and subtropical waters, but is sometimes found in temperate regions as well. We still know very little about the life of the Green turtle, and their exact movements and migratory routes are still highly unknown. We know that they engage in complex movements and migrate through geographically separated habitats. Female Green turtles nest in over 80 countries worldwide, and Green turtles have been spotted along the coast of more than 140 countries. 

Green turtles spend their life in the ocean and will only venture onto land in order to lay their eggs. It is only the female Green turtle who build nests; the male will stay in the water throughout his entire life, expect for the perilous walk from the nest to the water that all newly hatched Green turtles must embark on. Adult Green turtles from the subspecies Chelonia mydas agassizii have however been found basking on the beach together with seals and albatrosses.

The Green turtle is considered endangered and is included in the IUCN Red List of Threatened Species. The eggs are often removed by humans from the nesting beaches, and female that crawls out of the water to nest are hunted. Males and female Green turtles do not become sexually mature until they have reached an age of 10-24 years. They can live to be more than a century old. Estimating how many Green turtle specimens there are in the ocean is difficult, and many researchers count the number of nesting females and make estimations based on this number. A problem with this method is that it will only tell you how many females that nests in any give year; not the total amount of adult female Green turtles.