How Many Types Of Sea Turtles Are There?
Perhaps you have been lucky enough to see one. Maybe, idling your day away on a yacht in the Caribbean, gazing into the gin clear water, you spotted a huge, stately, slow-moving, dark, shape. It was coming up out of the water to take a breath. A sea turtle; one of nature’s rare treasures. Did you pick up your pina colada and speculate on the life of these mysterious animals with their calm, wise faces? We hope so. To find out more, read on.
Sea Turtles – The Basic Facts
Sea turtles are some of the oldest creatures on the planet. They are air-breathing reptiles, although they spend the vast majority of their lives at sea, coming to land just to lay their eggs on their favorite sandy beach.
Holding Their Breath For A Really Long Time
They can spend as much as seven hours underwater when they are inactive before they need to come to the surface to breathe. They can survive in highly salty water because they have special glands near their eyes that enable them to get rid of excess salt in their bodies. This has given rise to the myth that turtles cry. In fact, what people saw were the salt-eliminating glands at work.
Sea Turtles Are Under Threat From Every Side
There are seven species of sea turtles in all, six of which are considered to be endangered. The level of threat ranges from Critically Endangered to Vulnerable. Turtles were once found in their millions in the Caribbean. But over time, predation by man, loss of habitat, climate change, and prejudicial fishing methods have sadly reduced their numbers.
Some of the sea turtles are considered good to eat. They even play an important part in the sacred ceremonies of some peoples, for example, the Garinagu of Central America.
A Very Luxurious Soup
Turtle soup was long regarded as a special luxury, and was traditionally served at important occasions, such as the Lord Mayor’s Banquet in London. You may remember reading in “Alice in Wonderland” about “Soup of the evening, beautiful soup” and the Mock Turtle crying over it.
Pretty And Desirable
Artifacts made from turtle shells and skins have long been prized as ornaments, and also had practical uses in the days before plastic. Although the material is generally referred to as tortoiseshell, it was almost always turtle shell that was used.
A Key Element In The Diet Of The Past
Indigenous populations around the world have traditionally used sea turtles as part of their diet. A small population using non-commercial fishing methods meant that for thousands of years, this was sustainable. However, sea turtles have gone from being a sustainable source of food, especially for Caribbean nations, to being protected species. They are protectred under most legislations and by international agreement.
Sea turtles were first added to the CITES (Convention on International Trade in Endangered Species of Wild Flora and Fauna) list of endangered species as long ago as 1975.
Up until then, most people were not aware of their endangered status. Even now, there is a kind of out-of-sight, out-of-mind aspect to the protection of turtles. Perhaps this is because of their rather secretive lifestyle.
The Leatherback Turtle – The Big Boy Of The Gang
The leatherback turtle – Dermochelys coriace – is the world’s largest sea turtle. On average, they weigh between 600 and 800 pounds and are between 5 – 6 feet long. They can grow up to as much as 2,000 pounds in weight, and measure up to 8 feet long. Leatherbacks have been around since tyrannosaurus rex was duking it out with triceratops in major land battles 150 million years ago. The leatherback was enjoying the warm seas, and abundant prey, with not a human enemy to be seen. Leatherbacks get their name from their tough, leather-like skin. All the other turtles have shells, but this, the oldest of the sea turtle species, has that distinctive protective skin.
Because their skin can flex and their lungs can deflate to deal with high pressure, they can dive to incredible depths – to as much as over three thousand feet below sea level. They feed on soft sea creatures like jellyfish and squid. They need to eat around three-quarters of their own body weight every day. Leatherbacks travel enormous distances – close to 4,000 miles each way – to reach and return from their preferred breeding grounds. Like all turtles, they mate at sea and return to their home beach to lay their eggs in the sand.
The most dangerous time for any turtle is when it’s a hatchling, making its journey to the sea. Lights from human habitation can confuse them, so they head in the wrong direction. The hatchlings make good food for seabirds and sea creatures. Guarding nest sites and protecting the hatch is a key conservation activity not just for leatherbacks, but for all sea turtles. The leatherback turtle’s status around the world varies from vulnerable to endangered.
The Green Turtle – Creatures That Get Big From Eating Grass
The green turtle – chelonia mydas – gets its name from the greenish color of its fat. This color comes from the sea grass that forms a major part of its diet. It also eats soft floating creatures like jellyfish. Green turtles can grow up to four and a half feet long and can weigh up to 350 lb. Because they eat plants, they are usually found near the shore, and they live in sub-tropical and tropical waters throughout the world.
Meeting The Green Turtle At Sea
If you snorkel, scuba, or boat in the tropics, you are quite likely to spot one of these gentle turtles paddling along with its long fins and minding its own business. Don’t be afraid. He’s very gentle. Green turtles are considered good to eat, as are their eggs. This has led to a disastrous decline in their numbers. Other factors are pollution, especially run-off of chemicals from the land that destroys seagrass meadows, and getting caught in fishing gear.
The Hawksbill Turtle – They Just Love To Eat Sponge
Next down on the size list is the hawksbill turtle – Eretmochelys imbricate. This turtle gets its name from its characteristic beak-shaped mouth. It’s this turtle that has the beautiful shell that was used to make tortoiseshell ornaments and jewelry. Growing up to three feet in length and 125 lb in weight, this turtle inhabits tropical and sub-tropical seas, and can often be found near the coral reefs that are home to its favorite food – sea sponges.
Interestingly, the hawksbill has adapted to eat sponges that are poisonous to other sea creatures – giving it a unique place in the ecology of the sea. Very seriously endangered, the largest colony of hawksbill turtles can be found in Australia. It’s thought that there may only be eight thousand individuals left in the world, even though they can lay up to 300 eggs in a breeding cycle.
The Olive Ridley Turtle – Common But Mysterious
The olive ridley sea turtle – Lepidochelys olivacea – is probably the most common sea turtle in the ocean, believed to have around 800,000 nesting females. One of the smaller sea turtles, the olive ridley grows to around two and a half feet and weighs up to around 80 lb. It gets its name from its olive coloring. Although the population is large in comparison with other sea turtle populations, it is thought that numbers are decreasing. Not a great deal is known about these turtles. They are the subject of continuing research that will hopefully help in their conservation.
The olive ridley is best known for the arribadas, or arrival by sea, event when thousands of females come to the time-hallowed nesting beaches to lay their eggs. It is the monitoring of the numbers involved in this event that lead scientists to the conclusion that the population is in decline. The olive ridley is a wide-ranging seafaring turtle, spending most of its life on or near the surface of the ocean, feeding on soft sea creatures and plankton. They can dive to depths of around 650 feet but are most usually found at much shallower levels.
The Kemps Ridley – The World’s Rarest Sea Turtle
The kemps ridley turtle – Lepidochelys kempii – has the dubious honor of being the rarest sea turtle on earth. There are thought to be just 2,500 nesting females, and the species is confined to the Gulf of Mexico. Rather a small sea turtle, they grow to two feet long and up to 100 lb. They also have an arribadas event, at Rancho Nuevo in eastern Mexico. Unusually, they come to the beach during the day to lay their eggs. As a critically endangered species, they are strictly protected by the Mexican and US governments.
Efforts by Mexican fishermen to avoid catching turtles as by-catch are producing results. Lights on nets deter turtles (and as an added bonus increase the catch of desired fish). Escape hatches allow turtles caught in nets to get free. Interestingly, scientists have discovered that the temperature at which kemps ridley eggs are held affects whether the egg hatches out as a female or a male turtle. Eggs are collected, held at the correct temperature, and the ensuing baby turtles are released where predators can’t eat them.
The Loggerhead Turtle – The Turtle With A Head Like A Log
Well, it isn’t made of wood, of course, but it does look a bit like a log. Caretta caretta, as he is known to science, is one of the largest sea turtles. They grow up to three feet long and weigh in at around 300 lb. when fully grown. Individuals have been recorded weighing as much as 1000 lb. Like all turtles, the loggerhead has a long lifespan, living to be 67 or more years old. Loggerheads have been known to interbreed with other sea turtles, such as the kemps ridley, the hawksbill, and the green sea turtle. The product of this interbreeding is fertile – maybe we are seeing evolution in action here.
The loggerhead is very widely distributed and can be found in the Pacific, Mediterranean, Atlantic, and Indian oceans as well as in the Caribbean. They need warm water temperatures to be able to digest their food, and they aren’t picky about what they eat . They like fish, plants, algae – even hatchlings of their own species are all on the loggerhead menu. Active during the day, they, in particular the females, are very territorial and will fight over feeding areas. They spend around 85% of their time underwater, coming up for air and of course, to lay eggs during the nesting season.
Considered to be a vulnerable species, like all sea turtles the Loggerhead are affected by pollution, fishing, and climate change. Turtle eggs respond to the temperature of the sand in which they are laid with regard to the sex that they turn out to be. Higher sand temperatures will produce more females, and that may endanger the population balance.
The Flatback Turtle – The Down-under Wonder
Confined to Australian waters, the flatback turtle – Natator depressus – is one of the smaller of the sea turtles and has the most limited range. So-called because of the depression in the back of its carapace, or shell, it grows to 30″ and about 200 lb. Its range is very limited, nesting only on beaches in northern Australia, and frequenting the waters off Australia, Indonesia, and New Guinea. It’s quite a homebody, not traveling a long distance to migrate for nesting.
One of the interesting things about this turtle is the size of its hatchlings. Weighing in at a mighty 1 ½ lb., their size protects them from predators as they make their way to the sea and take their first hesitant swim through the breakers. Flatback turtles aren’t fussy about what they eat. They will eat plants, fish, jellyfish, algae, and whatever comes along. Although they are classified as a vulnerable population, they do have some encouraging characteristics, such as hatchling size and being omnivorous, that makes sea turtle enthusiasts somewhat optimistic about their chances of survival as a species.
How Can You Help Save the Sea Turtles?
There are plenty of ways you can help. One important thing is to be careful when discarding plastics near waterways. Cut fishing line into small pieces, cut fishing hooks up into smaller pieces, and cut through those plastic can holders. Don’t let plastic bags get into the garbage. Turtles and other sea creatures can mistake them for food and eat them, with devastating consequences.
If you want to donate to sea turtle conservation, there are several great organizations to choose from. These include the World Wildlife Fund. Turtle conservation organizations often need volunteers to help protect nests in tourist areas. This can be a worthwhile summer occupation for people both old and young.