Description and life history: Green sea turtles are large and long-lived marine turtles. Adults reach masses of up to 500 pounds, with most in the 240-420 pound range. Their average carapace length is about 40 inches. After hatching the color of the carapace and limbs is usually dark brown or black with a white lining. The coloration of adult carapaces is variable and ranges from light brown to dark olive, sometimes incorporating yellow streaks, and their plastron is whitish to dark yellow. The carapace is wide and smooth, and has large scutes that do not overlap. Each flipper possesses a single visible claw.
Green sea turtles were named because the layer of fat beneath their carapace is green due to the algae they consume. They can be most easily distinguished from other sea turtles because they have a single pair of prefrontal scales (in between the eyes).
Green sea turtles are they only herbivorous sea turtles as adults. As juveniles they are omnivorous and may eat jellyfish, crustaceans, etc. in addition to the grasses and algae that is typical of the adult diet.
The lifespan of green turtles can reach over 80 years in the wild. Reaching sexual maturity is a slow process lasting 10-40 years, with an average of 25. It is believed that female green sea turtles exhibit natal homing by returning to the beach at which they were born to nest. These migrations from feeding to nesting grounds may be upwards of 1,000 miles.
Green sea turtles lay about 115 eggs per clutch on average (only at night), and then leave the site. The incubation period of the eggs is about 60 days. Sex determination is temperature dependent, with males generally determined by lower temperatures and females by higher ones. Green sea turtles return to nesting sites every two to three years and lay up to six clutches per nesting season.
Location and Habitat: Green sea turtles are found worldwide in tropical and subtropical marine waters. When not migrating they prefer relatively shallow water in reefs, bays, or inlets. Such areas containing high levels of grasses and algae are most frequented.
Green sea turtle range is in beige. http://animals.nationalgeographic.com/animals/reptiles/green-turtle/
Personal Experience: I have witnessed green sea turtles on several occasions while snorkeling reefs and seagrass off of Saint John, USVI. I came across them mainly in the more protected bays. I saw the majority of them over seagrass as opposed to reef, although sometimes sand was the dominant substrate in the area. At times I was in the vicinity of multiple green sea turtles, once being able to see four directly in front of me. Often these turtles were fairly stationary, as opposed to the hawksbill turtles I saw that moved at a much greater rate and were more solitary.
My latest encounter with green sea turtles was in Port Aransas, Texas in February. They have a long jetty which is frequented by young green turtles and I saw one rise to the surface twice. Also, I was given a tour of an animal rehabilitation keep which had a handful of green turtles, including one brought in that day because it was nonfunctional due to cold shock.
Green sea turtle I saw off the coast of Saint John, USVI - late December 2010
Green sea turtle showing the diagnostic pair of prefrontal scales in between its eyes - yoto98.noaa.gov
Green sea turtle hatchling - thrivingoceans.org
http://www.fpir.noaa.gov/PRD/prd_green_sea_turtle.html http://www.fws.gov/northflorida/SeaTurtles/Turtle%20Factsheets/green-sea-turtle.htm
http://animals.nationalgeographic.com/animals/reptiles/green-turtle/
http://www.conserveturtles.org/seaturtleinformation.php?page=green
1 comment:
Thanks, David. How thrilling to see them in the wild!
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