Order: Testudines
Family: Chelonidae
Size: up to 80-150 cm in length.
Weight: up to 65-136.2 kg
Key Features: one of the largest and most widespread of all the marine turtles. The oval carapace varies from olive to brown, grey and black with bold streaks and blotches, but the common name, green turtle, is derived from the green colour of the fat and connective tissues of this species. The plastron, or undershell, remains a pale yellow or orange throughout life. Males are generally smaller than females and the green turtle differs in appearance from other marine turtles by the possession of a single pair of scales in front of the eyes and a serrated bottom jaw. The tiny black hatchlings are only around 5 centimetres long.
Breeding: Mating tends to occur just offshore of the nesting beaches, with the male green turtle using a curved claw on each front flipper and a flat nail at the end of the tail to grip the female. The female hauls out onto the beach at night and digs a large nest with the back flippers beyond the high tide mark, typically laying between 100 and 150 eggs before proceeding to cover the nest with sand. The female returns to breed only once every two to five years but will lay up to nine nests in that one season. Incubation takes between 45 and 70 days, and temperature has been shown to determine the sex of hatchlings; with females being produced at warmer temperatures. Breaking open the eggs with a special hooked 'egg tooth' that will subsequently be lost; hatchlings use their powerful front flippers to reach the surface, and then proceed to the sea.
Diet: almost exclusively herbivorous, grazing on sea grasses and algae, whilst the young are typically omnivorous, commonly feeding on jellyfish, molluscs and sponges.
Habitat: Normally inhabiting shallow developmental areas, rich in sea grass or marine algae, the green turtle migrates long distances every few years to the nesting beaches. Upon hatching, juveniles are thought to undertake an oceanic phase, where they possibly float passively on major current systems in the open ocean.
Habits: The green turtle has particularly slow growth rates and appears to take longer to become reproductively mature than any other sea turtle species, with age at sexual maturity ranging from 26 to 40 years. Undertaking tremendous feats of navigation, an adult green turtle will return to the same beach to breed each season.
Conservation Status: Endangered on the IUCN Red List of Threatened Species.
References:
South Atlantic Fishery Management Council (July, 2014)
http://www.safmc.net/Portals/0/ProtRes/New_PR/Spaccounts_sptable/pdf%20versions/Green%20Sea%20Turtle.pdf
Burnie, D. (2001) Animal. Dorling Kindersley, London.
Spotila, J.R. (2004) Sea turtles: a complete guide to their biology, behavior, and conservation. John Hopkins University Press, Baltimore and London.
Godley, B.J., Broderick, A.C., Frauenstein, R., Glen, F. and Hays, G.C. (2002) Reproductive Seasonality and Sexual Dimorphism in Green Turtles. Marine Ecology Progress Series, 226: 125-133.
Photo Courtesy
Brocken Inaglory, Licensed under CC BY-SA 3.0 Wikimedia Commons
Green Sea Turtle (Chelonia mydas)
