The Green Turtle is a large, solitary, primarily marine species of turtle. It is the largest of the hard-shelled turtles, reaching lengths up to 1.5 m in length and weights up to 315 kg (average weight 200 kg) (Wikipedia 2011, Wild Whales 2011). Body colour varies from olive-brown to black outlined in white (Wikipedia 2011, Wild Whales 2011). The carapace is pointed at the rear and varies in colour (green, brown, grey, black and yellow), while the lower shell is yellow-white (Wild Whales 2011). The body of the Green Turtle is dorsoventrally-flattened, the head is beaked (unhooked beak), the neck and snout are short, and arms are paddle shaped (Wikipedia 2011).
Wikipedia provides the following detail: "The horny sheath of the turtle's upper jaw possesses a slightly-denticulated edge while its lower jaw has stronger, serrated, more defined denticulation. The dorsal surface of the turtle's head has a single pair of prefrontal scales. Its carapace is composed of five central scutes flanked by four pairs of lateral scutes. Underneath, the Green Turtle has four pairs of infra-marginal scutes covering the area between the turtle's plastron and its shell. Mature Green Turtle front appendages have only a single claw (as opposed to the hawksbill's two), although a second claw is sometimes prominent in young specimens. The carapace of the turtle is known to have various color patterns that change over time. Underneath, the turtle's plastron is hued yellow. Limbs are dark-colored and lined with yellow, and are usually marked with a large dark brown spot in the center of each appendage".
The Green Turtle spends much of its time submerged either feeding or resting (Wikipedia 2011).
Green Turtles reach sexual maturity at between 20-40 years ofage (IUCN Marine Turtle Specialist Group 2011). They then reproduce every 2-4 years, digging nesting holes and laying 2-5 clutches of 80-120 eggs the size of ping-pong balls on beaches and coral atolls (IUCN Marine Turtle Specialist Group 2011). After eggs are deposited in the nest, females return to the ocean; eggs hatch at night and hatchlings immediately head to the sea (Wikipedia 2011).
"Green Turtles migrate long distances between their chosen feeding sites and the beaches from where they hatched. Some Green Turtles are known to swim distances of greater than 2,600 kilometers (1,400 nmi) to reach their spawning grounds. Mature turtles will often return to the same exact beach from which they hatched. Individual female green turtles usually mate every two to four years. Males on the other hand, are known to make the trip to their breeding areas every year. As with many species that are found across a wide range of latitudes, mating seasons vary between populations" (Wikipedia 2011).
Adult Green Turtles are obligate herbivores and feed on seagrasses and seaweeds, while juveniles feed on marine invertebrates, eating more plant material as they age (Wikipedia 2011).
Green turtles use a wide range of broadly separated localities and habitats during their lifetime, including sandy beaches and coral atolls for nesting, eelgrass beds for feeding, and open ocean for migration and development (Wikipedia 2011, Simenoff 2004). "Upon leaving the nesting beach, it has been hypothesized that hatchlings begin an oceanic phase (Carr 1987), perhaps floating passively in major current systems (gyres) that serve as open-ocean developmental grounds (Carr and Meylan 1980, Witham 1991). After a number of years in the oceanic zone, these turtles recruit to neritic developmental areas rich in seagrass and/or marine algae where they forage and grow until maturity (Musick and Limpus 1997). Upon attaining sexual maturity green turtles commence breeding migrations between foraging grounds and nesting areas that are undertaken every few years (Hirth 1997). Migrations are carried out by both males and females and may traverse oceanic zones, often spanning thousands of kilometers (Carr 1986, Mortimer and Portier 1989). During non-breeding periods adults reside at coastal neritic feeding areas that sometimes coincide with juvenile developmental habitats (e.g., Limpus et al. 1994, Seminoff et al. 2003)" ((Seminoff 2004).
The Green Turtle is an accidental species in British Columbia, where it is reported periodically. It is a highly migratory species with a circumglobal distribution and is found in tropical and (less often) subtropical waters in the Atlantic Ocean, Indian Ocean, Mediterranean Sea and the Pacific Ocean. It is found in coastal waters of more than 180 countries, and nests in more than 80 of these (Seminoff 2004). In the Pacific Ocean, it ranges from southern Alaska as far south as Chile, with two main breeding areas in the Northeast Pacific in Mexico and Hawaii (Wild Whales 2011). While mainly tropical in distribution, this species will follow warm currents north to BC and Alaska (Wild Whales 2011).
The Green Turtle is listed as threatened globally by the IUCN (2011). Reason for listing is given as: "Analysis of historic and recent published accounts indicate extensive subpopulation declines in all major ocean basins over the last three generations as a result of overexploitation of eggs and adult females at nesting beaches, juveniles and adults in foraging areas, and, to a lesser extent, incidental mortality relating to marine fisheries and degradation of marine and nesting habitats. Analyses of subpopulation changes at 32 Index Sites distributed globally (Figure 1, Table 1; see link to additional information below) show a 48% to 67% decline in the number of mature females nesting annually over the last 3–generations. "
"The green turtle has the most numerous and widely dispersed nesting sites of the seven species [of turtle], and was once highly sought after for its body fat – a key ingredient in the popular delicacy, ‘green turtle soup.’ Although it has become illegal to trade them in many parts of the world, green turtles and their eggs continue to be consumed" (IUCN Marine Turtle Specialist Group 2011).
"Eastern Pacific green turtles are termed ‘black turtles’ because of their darker coloration. They tend to be smaller and to lay fewer eggs than green turtles elsewhere" (IUCN Marine Turtle Specialist Group, 2011).
Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2019. E-Fauna BC:
Electronic Atlas of the Fauna of British Columbia [efauna.bc.ca]. Lab
for Advanced Spatial Analysis, Department of Geography, University of British
Columbia, Vancouver. [Accessed:
2021-04-18 10:39:58 AM]
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