Sea Turtle Species Profiles
Green Sea Turtle
Scientific Name: Chelonia mydas
IUCN/Conservation Status: Endangered - Green sea turtles are protected under the U.S. Endangered Species Act and listed as Endangered by the International Union for Conservation of Nature (IUCN). Other countries where it is illegal to harvest these turtles include Cuba, Mexico, The Bahamas, and Bermuda. Greens are also protected from commercial trade under the Convention on International Trade in Endangered Species (CITES), which is especially important due to their historical population decline from commercial trading (Witherington & Witherington, 2015).
Habitat and Distribution: Green sea turtles are found in warm waters around the tropics and subtropics in the Pacific, Atlantic, and Indian Oceans. On the east coast of the U.S.in the summer months these turtles can be found as far north as Cape Cod, Massachusetts. Throughout a green sea turtle's life, it will utilize habitats such as beaches, pelagic sargassum, seagrass beds, and nearshore reefs (Witherington & Witherington, 2015).
Diet: Juvenile green sea turtles are known to be omnivores and feed on blue buttons, copepods, and sargassum crabs. As they age, green turtles’ gut bacteria undergo a change allowing them to transition to herbivores, feeding primarily on seagrasses and algae. Although they become herbivores as they age, an adult green sea turtle is unlikely to pass up easily accessible animal prey and may still consume creatures such as jellies (Witherington & Witherington, 2015).
Size: Adult females typically weigh between 265 and 485 pounds. Their carapace can be between 78 and 119 centimeters (31 to 47 inches). Like loggerheads, the males are slightly smaller than the females (Witherington & Witherington, 2015).
Distinguishing Characteristics: While some believe green sea turtles’ carapaces appear green, they were actually named for the green color of their muscles and fat, which are tinted green because of their herbivorous diet. They have a serrated beak to assist with eating seagrasses. These turtles can also be characterized by their 4 lateral scutes that do not overlap (Witherington & Witherington, 2015).
Maturity and Reproduction: Green turtles reach maturity between 20 and 40 years old. While they mature at different ages, they also mature at different sizes. A green turtle that is growing more quickly may also mature faster. During mating season males will migrate to waters off the females’ nesting beaches. Males are likely to mate with multiple females and a single clutch can have 2 to 3 paternities (Witherington & Witherington, 2015).
Nesting: The nesting beaches of green sea turtles are found in warmer latitudes, in areas such as southern Mexico, southern Cuba, Caribbean Costa Rica, and southeastern Florida. Other areas of green sea turtle nesting include Australia, Africa, and many islands of the Indo-Pacific. The majority of green sea turtle nests in the U.S. are found in Florida. An average green nest will contain about 135 eggs and incubate for about 2 months (Witherington & Witherington, 2015). Green sea turtle nesting on Loggerhead Marinelife Center’s monitored beaches occurs from May into October. In 2020, 3,590 green sea turtle nests were laid on these 9.5 miles of monitored beach (Loggerhead Marinelife Center, 2021).
Conservation and Specific Human Impacts: Green sea turtles were once one of the most abundant animals found on earth. Greens have been hunted for their meat for thousands of years, but because of an increase in commercial harvest, the last few hundred have been the most detrimental to their populations. During the European colonization of the Caribbean, the colonizers began harvesting green sea turtles and storing them on their ships to maintain a constant supply of fresh meat. In the seventeenth century, the British began shipping around 13,000 green sea turtles a year back to Europe. By the early 1800s, the green sea turtle population in the Cayman Islands had severely diminished. To put this into perspective, it was once thought that millions of green sea turtles nested there and today there are only a handful of nests recorded each season in this area, meaning the populations still have not recovered.
In the southeastern United States, Green sea turtle overharvest began in the 1800s. Initially, harvesting took place in Key West. However, by the 1900s, most local populations were gone. The turtle fishermen of Key West were able to continue their fishery by harvesting in the western Caribbean. Thanks to conservation efforts, green nesting numbers have been on the rise. Although these turtles usually follow a 2 year trend of higher nesting numbers followed by a dip, the overall data is showing an increase in nesting numbers (Witherington & Witherington, 2015).
Local Impacts: Similar to loggerheads, boat strikes were the most common injury reported in green sea turtles during the 2020 sea turtle nesting season recorded by LMC biologists. (Loggerhead Marinelife Center, 2021). See what our Conservation department is doing to promote Responsible Boating Initiatives: https://marinelife.org/conservation/rbi/
Loggerhead Marinelife Center. (2021) Loggerhead Marinelife Center Sea Turtle Monitoring 2020 Nesting Season Final Report. 9-16.
Witherington, B., & Witherington, D. (2015) Our Sea Turtles: A Practical Guide for the Atlantic and Gulf, From Canada to Mexico. Pineapple Press, Inc.