Meet the Seven Sea Turtle Species
There are seven species of sea turtles, which are marine reptiles that need to breathe air to survive. Six of the seven species are found in US waters, and the flatback turtle is only found in the Western Indo-Pacific. Most of their lives are spent at sea, with some species diving to depths of 3000 feet (900 meters). They return to the shore to lay eggs, often making long journeys to go to specific beaches year after year.
Their wide-reaching movement and the small amount of time they spend on land means that it is hard to measure just how many sea turtles remain, or how many there used to be. (One estimate is that millions of green sea turtles were in the Caribbean at the time of Christopher Columbus.) Now all six of the species found in US waters are listed as endangered under the Endangered Species Act, and those six are also found on the IUCN Red List where their listings range from Vulnerable to Critically Endangered. They have many human-induced threats including entanglement in fishing gear, marine debris, coastal habitat destruction, poaching of adults and eggs, and climate change.
Green turtles (Chelonia mydas) live in the warm coastal waters of tropical and subtropical oceans. Adults sometimes eat sponges, salps (floating jelly-like animals), and jellyfish, but they feed mostly on plants, like seagrass and algae. The pigment from this green diet colors their fat, giving them their common name. Populations of female nesting green sea turtles are estimated to have dropped by 48% to 65% in the past 100 to 150 years. However, recent studies show that marine protected areas are benefitting the turtles.
Flickr user WLA
Kemp's Ridley Turtle
Kemp’s ridley turtles (Lepidochelys kempii) are the smallest sea turtles, weighing only 100 lbs (45 kg). Adults spend most of their time in shallow coastal areas in places with mud, sand, or gravel bottoms—often in seagrass beds. They eat swimming crabs, jellyfish and a variety of mollusks. This picture shows a female returning to the sea after laying her eggs in the sandy beach.
Terry Ross (Flickr user qnr)
Hawksbill turtles (Eretmochelys imbricata) are small to medium-sized turtles, but can get as large as 200 lbs (91 kg). Adults live among healthy coral reef communities, feeding primarily on sponges, but they also eat other invertebrates like sea cucumbers, tunicates (sea squirts), crabs, sea stars, and mollusks, as well as some algae.
Flickr user BarryFackler
Leatherback turtles (Dermochelys coriacea) are the largest sea turtles, growing as long as six and a half feet (2 m) and weighing some 2,000 pounds (900 kg). They’re unlike the other marine turtles in two important ways: they have a thick leathery carapace (outer covering) instead of a hard bony shell, and can survive in colder waters, allowing them to feed closer to the North and South poles where other turtles can’t survive. Their jaws are too weak to eat hard-bodied prey, so they mostly eat jellyfish and salps.
Claudia Lombard, USFWS
Loggerhead turtles (Caretta caretta) are named for their large heads and strong jaws, which allow them to eat prey with hard shells, like big marine snails. They live throughout the world’s warm tropical and subtropical oceans. They live off-shore when they’re young, and migrate closer to the coastline as they mature. Despite the decline in their populations around the world there is hope for further protection of these turtles through fisheries gear innovations and collaborations between scientists and governments.
Olive Ridley Turtle
Olive ridley turtles (Lepidochelys olivacea) are the smallest marine turtle, living in warm waters close to shore as adults. Female olive ridleys take part in mass nestings that can involve 150,000 individual turtles crawling up a beach at night to find a spot for their clutch of around 100 eggs.
Flickr user Nodnarb Truk
Flatback Sea Turtle
Unlike the other six species of marine turtle, the Australian flatback (Natator depressus) has a very limited distribution, found only from northern Australia to Papua New Guinea/Indonesia and it only breeds in Australia. Flatback turtles tend to spend most of their time at the ocean's surface, often with a bird making use of their shell as a small landing space perfect for a break.