The Green Sea Turtle | Anatomy
Chelonia mydas, or more commonly known as the Green Sea Turtle, is one of the largest sea turtles in the world. Adult Green Sea Turtles can grow up to 5 feet long and weigh up to 317 kilograms. This is equivalent to about 700 pounds; which can make them twice or thrice as heavy as a human being. The Green Sea Turtle’s heart-shaped shell can measure up to 1.5 metres in width. Contrary to popular belief, the Green Sea Turtle is not named for the colour of its shell (which is brown, black, gray or green, depending on where the turtle lives), but for the green tinge of fat which can be found beneath its shell. The Green Sea Turtle has no teeth and its head is similar to that of a lizard’s.
Green Sea Turtles can be differentiated from other sea turtles in that they have beautiful, distinctive facial markings unique to each specific turtle. This helps researchers identify them. As with other sea turtles, Green Sea Turtles cannot push their heads back into their shells. What serves as their protection instead is the thick, scaly skin which is found on the back of their heads and necks. Luckily, Green Sea Turtles do not have many enemies in the wild. This is likely due to their size. Some enemies that they do have are large species of sharks (namely tiger sharks) and sadly, human beings. One particular threat posed by human beings is “ghost nets” which are left carelessly by fishermen in the ocean. Green Sea Turtles are often caught in these nets, leading them to get trapped, which means that they are unable to swim properly to capture food. If they are unable to catch food, obviously, they eventually die.
The Green sea turtle has a small and blunt head with a serrated jaw. The body is nearly oval and a beaked head at the end of a short neck. The arms are paddle-like flippers that are adapted for swimming. On each flipper there’s 1 visible claw. .
As with other sea turtles, the shell of the Green Sea Turtle also serves as its skeleton. At two years old, the shell of a Green Sea Turtle is approximately 14 inches in length. The shell of the Green Sea Turtle is very smooth. The colour of the shell can change as the turtle gets older. At present, there is a debate between scientists as regards the types of Green Sea Turtles that exist. In any case, whether they are subspecies or separate species, there are two types of Green Sea Turtles. The first is the Atlantic Green Sea Turtle and the second is the Eastern Pacific Green Sea Turtle. The Atlantic Green Sea Turtle can be found in the shores of North American and Europe, while the Eastern Pacific Green Sea Turtle is normally seen in coastal waters from Chile to Alaska.
The carapace color varies from pale to very dark green and plain to very brilliant yellow, brown and green tones with radiating stripes. The plastron varies from dark grey-bluish-green in the Pacific populations to white, dirty white or yellowish in the Atlantic populations.
The adults are 75-90 cm in carapace length with an average weight around 200 kg. There have been caught Green sea turtles that have reached weights up to 310 kg. The largest green turtle ever found was 152 cm in length and 395 kg.
As with the other sea turtles Green turtle breaks the surface to breathe. They spend almost all their lives submerged but have to breathe air. The time submerged depends on the activity level.
Green Sea Turtles are known to glide through the water with speeds as fast as 24 kilometres per hour. There have been recorded instances of Green Sea Turtles swimming up to 4,828 kilometres at a time. Although most of a Green Sea Turtle’s life is spent submerged, it is necessary for them to absorb oxygen to compensate for vigorous activities such as food hunting. Green Sea Turtles are amazing creatures in that they can rapidly inhale and exhale in a single breath to replace the air in their lungs. Their lungs have adapted in such a way that gasses do not get trapped during their deep dives into the ocean. Oxygen is delivered efficiently into their lungs even with the extreme pressure they encounter as they dive. Green Sea Turtles can rest or sleep underwater for hours at a time but this time is shortened when activity is involved. Green Sea Turtles dive for about four to five minutes and rise to the surface for air for one to three seconds.
Again, as with many species, male Green Sea Turtles are often larger in size than female Green Sea Turtles. They also have longer tails. The shells of male Green Sea Turtles are also narrower. The curved claws on the front flippers of males are also enlarged. This helps them to firmly grip the female during the mating process. Both male and female sea green turtles have flippers which are paddle-like. This characteristic of theirs is what makes Green Sea Turtles graceful and powerful swimmers. In contrast to other sea turtles and to the Atlantic Green Sea Turtle, the Eastern Pacific Green Sea Turtle is quite unique in that it is often spotted basking in the sun to warm itself. What other sea turtles often do is swim close to the surface of shallow waters. Once in awhile, the Eastern Pacific green turtle is seen sunbathing side by side with albatrosses and seals. While most sea turtles rarely leave the water for any other purpose but to nest, the Eastern Pacific green turtle is an exception.