Sea Turtles

Sea turtles are among the oldest creatures on earth and have remained essentially unchanged for 110 million years. However, they face an uncertain future due to threats of many kinds.

Green Sea Turtle

There are seven species of sea turtle: green, hawksbill, leatherback, loggerhead, olive ridley, Kemp’s ridley and flatback. All but the olive ridley and flatback are found in Florida. The six below are found within the US. 

Description

Sea turtles are air-breathing reptiles remarkably suited to life in the sea. Their hydrodynamic shape, large size, and powerful front flippers allow them to dive to great depths and swim long distances. After their first frantic crawl from the nest to the ocean, male sea turtles never return to the shore again, and females come back only long enough to lay eggs.

Sea turtles have long and narrow wing-like flippers in place of forelimbs and have shorter flippers as hind limbs; unlike their terrestrial relatives, they cannot retract their heads into their shells.

In most sea turtles, the top shell, or "carapace", is composed of many bones covered with horny scales or "scutes." Turtles are toothless but have powerful jaws to crush, bite, and tear their food.

The smallest of the sea turtles are the ridleys, weighing in at 85 to 100 pounds as adults. Leatherbacks are the behemoths and can grow to 2,000 pounds. Most sea turtles grow slowly and have a life-span of many decades. Although sea turtles can remain submerged for hours at a time while resting or sleeping, they typically surface several times each hour to breathe.

Habitat

Newly hatched sea turtles inhabit a much different environment than adult turtles. After emerging from the nest, hatchlings enter the water and must swim quickly to escape near shore predators. There is strong evidence that many sea turtle species employ an open ocean developmental stage because encounters with healthy, neonate sea turtles are extremely rare in near shore waters.

Juveniles of many species of sea turtles have been known to associate with floating sargassum seaweed, utilizing the sargassum as an area of refuge, rest, and/or food. This developmental drifting period is hypothesized to last about two years or until the turtle reaches a carapace length of about 8 inches (20 cm).

Subsequently, these sub-adult turtles return to neritic zones of the Gulf of Mexico or northwestern Atlantic Ocean to feed and develop until they reach adulthood.

Reproduction

Leatherback Sea Turtle Hatchling

Mating occurs roughly every 2 to 3 years in shallow waters. In summer, an ancient reproductive ritual begins when the female leaves the sea and crawls ashore to dig a nest in the sand. She uses her rear flippers to dig the nest hole and then she deposits 80 - 150 eggs that look a lot like ping-pong balls.

When egg-laying is complete, the turtle covers the eggs, camouflages the nest site, and returns to the ocean. Nesting turtles may come to shore several times in a nesting season to repeat the process.

As is true for some other reptiles, the temperature of the sea turtle nest determines the sex of the hatchlings. Warmer temperatures produce more females, whereas cooler temperatures result in more males. Consequently, conservationists and wildlife managers leave turtle eggs in their original location whenever possible so that sex ratios are determined naturally.

After incubating for about two months, the eggs begin to hatch. Hatchlings range from 1.5 - 3 inches in size, depending on the species, and emerge from the nest as a group. This mass exodus usually occurs at night, and the hatchlings use the bright, open view of the night sky over the water to find their way to the sea. Artificial lights on beachfront buildings and roadways can distract hatchlings on their way to the ocean. Because of this danger, many beachfront communities in Florida have adopted lighting ordinances requiring lights to be shut off or shielded during the nesting and hatching season.

Track a Sea Turtle! 

See where sea turtles go at the Sea Turtle Conservancy website.

Threats

All sea turtles are endangered. NOAA provides the status of sea turtle species.

In general, sea turtles are threatened by the following risks:

In the U.S., NOAA's National Marine Fisheries Service (NMFS) and the U.S. Fish and Wildlife Service (USFWS) have joint jurisdiction for marine turtles:

  • NMFS has the lead in the marine environment
  • USFWS has the lead on the nesting beaches

National Wildlife Federation links

Oil Spill Effects on Sea Turtles

Green Sea Turtle

 

Sources

U.S. Fish and Wildlife Service

NOAA National Marine Fisheries Service

NOAA Fisheries Office of Protected Resources

Florida's Fish & Wildlife Research Institute

University of Michigan’s Animal Diversity Web

Sea Turtle Conservancy

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