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Ocean Life: Green Sea Turtle - Characteristics


Green Sea Turtles get their name from the color of their body fat, which is green from the algae or grasses they eat. The Hawaiian Green Sea Turtle population, is known by its Hawaiian name Honu.


Green Sea Turtles are reptiles whose ancestors evolved on land and returned to the sea to live. The first turtles appeared during the Triassic period, 245 to 208 million years ago. Fossils for the earliest known sea turtles appear in the Late Jurassic period, 208 to 144 million years ago. Turtles are one of the few species that watched the dinosaurs evolve and become extinct.

A Green Sea Turtle

As reptiles, sea turtles possess the following traits:

  • They are cold-blooded, meaning they get their body heat from the environment.
  • They breathe air.
  • Their skin is scale


Now, scientists recognize seven species of these marine reptiles. The recognized sea turtle species are as follows: Greens, Hawksbill, Kemp's Ridley, Olive Ridley, Loggerhead, Flatback and Leatherback. The Loggerhead Sea Turtle is listed as threatened, the Flatback is listed as vulnerable, and all other species are listed as endangered. Green Sea Turtle populations of Hawaii are threatened and protected in Hawaii under state law. Populations of Green Sea Turtles off the coast of Florida and the Pacific coast of Mexico are listed as endangered. Green Sea Turtles are protected by the federal Endangered Species Act, and listed under the Convention on International Trade of Endangered Species (CITES). CITES makes it illegal to import or export turtle products.


In addition to their reptilian traits, all species of turtles except the Leatherback have evolved a bony outer shell, which protects them from predators. The Leatherback is the only soft-shelled sea turtle and is in a family by itself. The shell covers the dorsal (back) and ventral (belly) surfaces of a sea turtle. The dorsal portion of the shell is the carapace and is covered with scale-like structures called scutes, while the ventral portion of the shell is known as the plastron. Experts can identify species of sea turtles by the number and pattern of scutes on the carapace. The shell is considered the most highly developed protective armor of any vertebrate species. While most land turtles can retract their heads into their shells for added protection, sea turtles cannot and their heads remain out at all times.


Green Sea Turtles have green flesh. The carapace is olive brown to black, while the plastron is pale yellow to creamy white. The carapace is molted, variegated in color. Rarely will you find a Green Sea Turtle with a solid colored shell. Counter-shading of the shell conceals the turtle from predators, making it difficult to distinguish the dark carapace from the sea floor and the light plastron from the lighter sky.


Green Sea Turtles as hatchlings weigh about an ounce and have a carapace length of 2 inches. A sexually mature green sea turtle weighs 200-350 pounds with a carapace length of 2.5 feet. Adults grow to a carapace length of 3.5 feet and weigh an average of 400 pounds. One of the largest turtles that ever lived from the Late Cretaceaus period, 144 to 65 million years ago, reached a length of 9.8-13 feet.


The lifespan of sea turtles is not known. It is believed that Green Sea Turtles reach sexual maturity around the age of 25 years and can live up to 80 years of age. The long period of maturation helps to explain why it takes turtles so many years to recover from a population decline.


Sea turtles are wonderfully adapted to life in the ocean. Their shells are lighter and more streamlined than land turtles. Front and rear limbs have evolved into flippers. These flippers make sea turtles efficient and graceful swimmers, capable of swimming long distances in a short time.


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