Being Green

By Kim Kardas

Here in Brevard County, green sea turtles are now nesting on the beaches. The green sea turtle, or Chelonia mydas, nests regularly on Florida beaches from June through late September. Green turtles are the last of the sea turtle species to come ashore, after the leatherback and loggerhead turtles that regularly nest in Florida as well.

In 2020, more than 12,000 green sea turtle nests were recorded in Brevard County and more than 26,600 were recorded statewide. Since 1989, totals statewide have ranged from less than 300 to nearly 41,000 in 2019. Green sea turtle nesting numbers tend to fluctuate in an every-other-year pattern with high totals in 2011, 2013, 2015, 2017, and 2019.

Green turtles nest every 2-5 years and typically return to the same nesting region each season. Males mate with females in the water in foraging grounds, along migratory pathways, and near nesting beaches. Females emerge on nesting beaches at night and lay their eggs in a process that can take up to two hours to complete. The eggs are deposited into an egg chamber that the female digs, and afterward is covered and camouflaged for protection against predators.

Nesting can occur as many as seven times per season, with an average clutch size of 110-115 eggs, according to the Florida Fish and Wildlife Conservation Commission. The incubation time for the eggs is about 60 days, or two months, and then the hatchlings will emerge and head directly to the ocean.

Green turtle hatchlings are unique because of their countershading coloration, which means that their carapaces, or shells, are colored dark while their plastron, or underside, is colored light. This countershading allows the hatchlings to better blend with their environment and disguises them from predators both above and below. As the hatchlings grow into juveniles, their carapace and scutes develop color patterns of yellow, brown, and olive, creating the appearance of an adult green sea turtle. After hatching, green sea turtles spend years living in the pelagic zone and do not reach sexual maturity until they are 25-35 years old.

Sources:

https://www.fisheries.noaa.gov/species/green-turtle

https://myfwc.com/wildlifehabitats/profiles/reptiles/sea-turtles/green-sea-turtle/