What are the species of sea turtles

Order: Testudines

Status: Endangered

Description

Sea turtles are 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. These front flippers are long, narrow, and winglike, while their hind flippers are shorter. Although sea turtles can remain submerged for hours at a time while resting or sleeping, they typically surface several times each hour to breathe.

There are seven species of sea turtle: the green sea turtle, Hawksbill sea turtle, loggerhead sea turtle, olive ridley sea turtle, Kemp’s ridley sea turtle, leatherback sea turtle, and flatback sea turtle.

Sea turtles are among the oldest creatures on Earth and have remained essentially unchanged for 110 million years. In most sea turtles, the top shell—or carapace—is composed of many bones covered with horny scales, or scutes. Unlike their terrestrial relatives, they cannot retract their heads into their shells. The smallest of the sea turtles are the two species of ridleys, weighing in at 85 to 100 pounds (38 to 45 kilograms) as adults. Leatherbacks are the biggest and can grow to 2,000 pounds (900 kilograms). Most sea turtles grow slowly and have a lifespan of many decades.

Range

Of the seven sea turtle species, the flatback is the only one not found in U.S waters. It is only found off the coasts of Australia.

Life History

Mating occurs roughly every two to three 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, then deposits 80 to 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. For this reason, 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 to 3 inches (3.8 to 7.6 centimeters) in size, depending on the species, and emerge from the nest as a group. This 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. 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.

Artificial lights on beachfront buildings and roadways—often called light pollution—can distract hatchlings on their way to the ocean. Because of this danger, many beachfront communities have adopted lighting ordinances requiring lights to be shut off or shielded during the nesting and hatching season.

Conservation

All sea turtles are threatened or endangered. They face an uncertain future due to threats of many kinds, including pollution and the encroachment of coastal development on their nesting beaches. They are also susceptible to accidental drowning in fishing gear and are at risk from the international trade in turtle meat and shell products.

In the United States, the U.S. Fish & Wildlife Service and the National Oceanic and Atmospheric Administration's National Marine Fisheries Service have joint jurisdiction for marine turtles: the National Marine Fisheries Service has the lead in the marine environment, while the U.S. Fish & Wildlife Service has the lead on the nesting beaches.

Fun Fact

Sea turtles are toothless, but have powerful jaws to crush, bite, and tear their food.

Sources

Animal Diversity Web, University of Michigan Museum of Zoology

Fish and Wildlife Research Institute, Florida Fish and Wildlife Conservation Commission

National Marine Fisheries Service, National Oceanic and Atmospheric Administration

Sea Turtle Conservancy

U.S. Fish & Wildlife Service

Sea turtles are charismatic animals that have been around for millions of years. There is some debate on the number of sea turtle species, although seven have traditionally been recognized.

Six of the species are classified in the Family Cheloniidae. This family includes the hawksbill, green, flatback, loggerhead, Kemp's ridley, and olive ridley turtles. These all look fairly similar when compared to the seventh species, the leatherback. The leatherback looks very different from the other species and is the only sea turtle species in its own family, Dermochelyidae.

All seven species of sea turtles are listed under the Endangered Species Act. 

Leatherback Turtle

The leatherback turtle (Dermochelys coriacea) is the largest sea turtle. These gigantic reptiles can reach lengths of over 6 feet and weights of over 2,000 pounds.

Leatherbacks look very different from other sea turtles. Their shell consists of a single piece with five ridges, which is distinctive from other turtles who have plated shells. Their skin is dark and is covered with white or pink spots. 

Leatherbacks are deep divers with the ability to dive to over 3,000 feet. They feed on jellyfish, salps, crustaceans, squid, and urchins.

This species nests on tropical beaches, but can migrate as far north as Canada during the rest of the year. 

Green Turtle

The green turtle (Chelonia mydas) is large, with a carapace of up to 3 feet long. Green turtles weigh up to 350 pounds. Their carapace can include shades of black, gray, green, brown, or yellow. Scutes may contain a beautiful pigmentation that looks like a sun's rays. 

Adult green turtles are the only herbivorous sea turtles. When young, they are carnivorous, but as adults, they eat seaweeds and seagrass. This diet gives their fat a green tinge, which is how the turtle got its name.

Green turtles live in tropical and subtropical waters around the world.

There is some debate over green turtle classification. Some scientists classify the green turtle into two species, the green turtle and the black sea turtle or Pacific green sea turtle.

The black sea turtle may also be considered a subspecies of the green turtle. This turtle is darker in color and has a smaller head than the green turtle.

Loggerhead Turtles

Loggerhead turtles (Caretta caretta) are a reddish-brown turtle with a very large head. They are the most common turtle that nests in Florida. Loggerhead turtles can be 3.5 feet long and weigh up to 400 pounds.

They feed on crabs, mollusks, and jellyfish.

Loggerheads live in temperate and tropical waters throughout the Atlantic, Pacific, and Indian Oceans.

Hawksbill Turtle

The hawksbill turtle (Eretmochelys imbricate) grows to lengths of 3 1/2 feet long and can weigh up to 180 pounds. Hawksbill turtles were named for the shape of their beak, which looks similar to the beak of a raptor. These turtles have a beautiful tortoiseshell pattern on their carapace and have been hunted nearly to extinction for their shells.

Hawksbill turtles feed on sponges and have an amazing ability to digest the needle-like skeleton of these animals.

Hawksbill turtles live in tropical and subtropical waters in the Atlantic, Pacific, and Indian Oceans. They can be found among reefs, rocky areas, mangrove swamps, lagoons, and estuaries.

Kemp's Ridley Turtle

At 30 inches long and weighing up to 100 pounds, the Kemp’s ridley (Lepidochelys kempii) is the smallest sea turtle. This species is named after Richard Kemp, the fisherman who first described them in 1906.

Kemp's ridley turtles prefer to eat benthic organisms such as crabs.

They are coastal turtles and found in temperate to subtropical waters in the western Atlantic and Gulf of Mexico. Kemp's ridleys are most often found in habitats with sandy or muddy bottoms, where it is easy to find prey. They are famous for nesting in huge groups called arribadas. 

Olive Ridley Turtle

Olive ridley turtles (Lepidochelys olivacea) are named for—you guessed it—their olive-colored shell. Like the Kemp’s ridley, they are small and weigh less than 100 pounds.

They eat mostly invertebrates such as crabs, shrimp, rock lobsters, jellyfish, and tunicates, although some primarily eat algae. 

They are found in tropical regions around the world. Like Kemp's ridley turtles, during nesting, olive ridley females come to shore in colonies of up to a thousand turtles, with mass nesting aggregations called arribadas. These occur on the coasts of Central America and India.

Flatback Turtle

Flatback turtles (Natator depressus) are named for their flattened carapace, which is olive-gray in color. This is the only sea turtle species not found in the United States.

Flatback turtles eat squid, sea cucumbers, soft corals, and mollusks. They are found only in the coastal waters of Australia.

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