It looks as if endangered green sea turtles are making a comeback on Florida shores. Biologists at the Archie Carr National Wildlife Refuge in Florida are finding more and more green sea turtle nests and hatchlings on the area's beaches. In November of 2013, Ericka Angulo of NBC News reported, "In 1979 there were only 62 nests in the state, according to the Florida Fish and Wildlife Conservation Commission.

This year, there were 35,000."

Appearance

The green sea turtle (Chelonia mydas) is a large, heavy sea turtle that has a wide, smooth shell (also known as a carapace). While its shell is generally gray or brown, the turtle's skin is green, which lends the species its name. The turtles' flippers are shaped like paddles to help propel them swiftly and gracefully through the water. Unlike terrestrial turtles, the green sea turtle cannot pull its head inside its shell.

Size

They can measure up to 5 feet (1.5 meters) in length and weigh up to 700 pounds (317.5 kilograms). Males are slightly larger than females and have longer tails. Hatchlings are about 2 inches (50 millimeters) in length.

Habitat

The green sea turtle inhabits tropical and subtropical coastal waters around the world. The nest on sandy beaches.

Diet

The adult green sea turtle is herbivorous, unlike other species of sea turtle, meaning it only eats plants like sea grasses and algae. Juvenile green turtles eat these plants as well as invertebrates like crabs, jellyfish, and sponges.

Habits

Most species of sea turtles, which are all cold-blooded reptiles, warm themselves by swimming close to the surface of shallow waters to feel the sun's rays. They only leave water for land during nesting times. However, the Eastern Pacific green sea turtle is known to climb out onto land in order to bask in the sun, often accompanying seals and albatrosses.

Reproduction

Like other sea turtles, the green turtle migrates long distances from feeding sites to nesting beaches. Mating occurs only every two to four years, and it usually happens in shallow waters close to shore. When they're ready to lay their eggs, females turtles often return to the same beach where they were hatched. They dig a hole in the sand with their flippers, deposit a clutch of 100 to 200 eggs, and then cover the eggs with sand before returning to the sea. With no further maternal care, the eggs hatch after about two months, and the baby turtle make the perilous journey from sand to sea. The scampering hatchlings are preyed upon in droves by crabs and flocks of sea gulls.

Lifespan

These turtles live between 20 and 50 years on average, but they can live over 80 years.

Geographic Range

Tropical and subtropical coastal waters around the world

Conservation Status

Endangered (a subpopulation in the Mediterranean is listed as critically endangered)

Estimated Population

According to the National Marine Fisheries Service, the two largest nesting populations are found at Tortuguero, on the Caribbean coast of Costa Rica (where 22,500 females nest per season on average) and on Raine Island, on the Great Barrier Reef in Australia (where 18,000 females nest per season on average). In the U.S., green turtles nest primarily along the central and southeast coast of Florida where an estimated 200 to 1,100 females nest annually.

Population Trend

There has been an estimated 48 to 65 percent decline in the number of mature females nesting annually over the past 100 to 150 years.

Causes of Population Decline

Green sea turtle have long been hunted, and still are, for their meat and eggs. Other modern threats include encounters with boat propeller, drowning in fish nets, and the destruction of the beaches they need for nesting by human development and recreation.