Ancient creatures, sea turtles, also known as marine turtles, have braved various eras to survive until today. Between the extinction of dinosaurs and major climate changes, nothing stops them, and yet, one obstacle always stands in their way: humans. Let's take a closer look at the different species of sea turtles and the solutions to protect them.
The 7 species of sea turtles
Worldwide, more than 300 species of turtles exist. 250 of them live in aquatic environments (freshwater, wet and marshy areas) while 60 species prefer a terrestrial environment. Sea turtles are reptiles that have a pulmonary respiratory system, allowing them to live on Earth a long time ago. They also have kidneys and tear glands near their eyes, which serve to expel excess salt from their bloodstream. With an incredible metabolism, sea turtles are capable of diving to very great depths and withstanding high concentrations of CO2. However, it is quite difficult to determine the sex of a sea turtle. This often requires the intervention of a specialist or a veterinarian who will perform a genetic examination. One can, however, look at the size of the tail or claws (both of which are longer in males) depending on the species, but some females have the same characteristics, which makes identification by deduction fruitless.
Regarding their senses, sea turtles have excellent eyesight as their eyes are highly developed, with no less than three eyelids. They also have a very keen sense of hearing which resonates in an inner ear, beneath an auditory plate. This allows them to hear everything happening around them and to flee dangers such as predators. The least developed sense in sea turtles is smell, which is not very efficient. Finally, although sea turtles are often mocked for their slowness, some species can still reach speeds of 35 km/h !
Today, we will focus specifically on the seven different species of sea turtles. Indeed, in France, 6 of these 7 species live in the country's waters.
The Leatherback turtle: the largest of the turtles
The Leatherback turtle is the largest turtle species in the world. It belongs to the Dermochelyidae family and is, in fact, the only species in this family, which distinguishes it from other sea turtles. Its main difference is that its carapace is not covered with scales but instead has very hard and leathery skin. As an adult, it can weigh up to 400 kg and measure up to two meters in length!
The Green turtle: blending into landscapes and nature
The green turtle is the largest of its family, the Cheloniidae. It generally measures between 80 cm and 130 cm. Its weight can reach 250 kg, but the average for this species is 160 kg. When it is young, the green turtle is carnivorous, feeding on fish and small crustaceans. Once it reaches adulthood, it completely changes its diet and becomes vegetarian! This is why it is called the Green turtle, as the color of its flesh is literally green and thus represents its diet, unlike other sea turtle species. This characteristic color allows it to blend in and hide from predators amidst vegetation.
The Loggerhead turtle: a formidable jaw
The Loggerhead turtle sports a pretty brown color. It measures up to 120 cm and weighs up to 200 kg. It is a carnivorous species with an incredibly powerful jaw. Thanks to its maxillary muscle, it can crush crustaceans before ingesting them. It also feeds on jellyfish, crabs, and shrimp, as well as small fish.
The Hawksbill turtle: prized for its beauty
The Hawksbill turtle weighs from 60 to 90 kg and its size generally ranges from 60 to 120 cm. This species is omnivorous and has the particularity of feeding on sponges, which makes its skin and thus its meat toxic to humans. Unfortunately, this defense mechanism is not enough, as it is perpetually hunted by poachers who seek to tear off its scales, to use them as material for artisanal creations such as combs or jewelry in certain regions of the world.
The Olive Ridley turtle: an exceptional layer
The Olive Ridley turtle owes its name to the olive-green color of its shell. It is considered a "small turtle" (though still massive on a human scale) as it measures 50 to 75 cm and weighs 40 to 50 kg. This species is particularly known for arriving in massive numbers on the beaches of the Pacific coasts of Central America, such as Mexico, Costa Rica, and Panama, but also in South America, on certain coasts of Suriname, to lay its eggs.
Kemp's Ridley turtle: rare and discreet
Kemp's Ridley turtle is the smallest species of sea turtle: it measures 45 to 70 cm and weighs 30 to 50 kg. It can be considered the little sister of the Olive Ridley turtle. Very rare and discreet, it primarily lays its eggs on the Mexican beach of Playa de Rancho Nuevo. It can also be found in the Pacific Ocean off Nova Scotia. This species is highly endangered, as in 1947, the number of breeding females was estimated at 47,000. In the interim, this figure plummeted to a few hundred in the 1970s, then, thanks to protection efforts, the number has risen today to around 1,000, which is still insufficient for the guaranteed survival of the species.
The Flatback turtle: a flat shell
The last known species of marine turtle is the flatback turtle, which owes its name to its particularly flat shell. It lives exclusively between Australia, Papua New Guinea, and Indonesia. It can measure from 95 to 130 cm and weigh from 100 to 150 kg. It feeds mainly on sea cucumbers, shellfish, and jellyfish, which makes it a carnivore. Currently, only a few beaches in northern Australia harbor them for reproduction.
The major dangers threatening sea turtles
There are 3 main dangers that threaten the different species of sea turtles: pollution, poaching, and accidental bycatch. These three factors are at the heart of the problem of species disappearance, leading to a complete change in the behavior of marine turtles.
Pollution
This is a rather obvious cause. Pollution of marine waters poses great dangers for the conservation of sea turtles. Indeed, discarding waste into seas and oceans leads to the decomposition of natural habitats, as well as coral, and consequently the disappearance of certain marine species, which serve as food for turtles. To survive, sea turtles are therefore forced to migrate to other regions of the world, in search of a new place to live, which is not always easy because several conditions must be met for their survival. Moreover, plastic is the material most often discarded into the environment and it is highly harmful and toxic to turtles (as well as to birds or whales, for example). Indeed, they are attracted by its smell and confuse it with jellyfish, since plastic becomes a habitat for various algae and crustaceans. They then feed on these plastic bags which damage their intestines. It is not uncommon to also find sea turtles with plastic straws stuck in their noses, which causes ingestion that can lead to death...
Poaching
Poaching is the second cause explaining the disappearance of sea turtles. Indeed, the illegal trade in marine animals generates several billion euros per year for the networks that orchestrate it. Wildlife trafficking ranks fourth among the most lucrative criminal activities, just behind drug trafficking, counterfeiting, and human trafficking. Contrary to what one might think, poachers are true crime professionals and are very well organized. Like real armies, they do not hesitate to enter protected territories and have high-end and expensive equipment to hunt turtles. Once caught, turtles are killed and dismembered to be made into hunting trophies or to create handicrafts with their scales or shells. It is a vicious circle because the rarer the turtles are, the more they are hunted and coveted. Many associations are trying to fight against these still too common abuses, and the dismantling of criminal poaching networks is increasing. Unfortunately, legal remedies remain weak depending on the areas of the world, which offers poachers almost certain protection in most cases, so there is also legislative work to be considered for a better future.
Accidental catches
The last danger facing sea turtles concerns fishing. Indeed, marine turtles are subject to unwanted and accidental catches, just like sharks, dolphins, and some seabirds. Trapped in nets, turtles panic and suffocate. J-shaped hooks are also very harmful to turtles, as they get caught in their jaws and even when released, they retain an open wound. Gradually, associations are trying to implement new types of hooks whose shape does not injure the animals, with the aim that they can be released immediately without after-effects. Finally, bottom trawling is also an aggravating factor and a threat to the lives of sea turtles. Indeed, trawling involves dropping a fishing net to the bottom of the water with the aim of bringing it back up with species on board. This type of fishing destroys natural habitats at the bottom of the water and leads to the capture of protected species.
Other causes of sea turtle extinction
In addition to these 3 main threats, sea turtles are exposed to several other dangers. Firstly, climate change is a factor that can impact marine turtle populations. Rising sea levels create an imbalance by reducing the turtles' nesting areas. Moreover, the determination of a turtle's sex depends on temperature. Thus, an increase in temperature at nesting beaches can lead to an imbalance between the proportion of males and females within the species. Furthermore, diseases are also increasingly present in turtles. Often due to pollution, recent reports indicate a disease called fibropapillomatosis: it is a type of tumor that can kill turtles. In the Hawaiian Islands, nearly 70% of stranded green turtles are infected with this destructive disease. Finally, the last threat concerns the introduction of new predators by humans. Although marine turtles can lay more than 150 eggs per clutch and have several clutches per season, fewer and fewer hatchlings survive and manage to reach the shore or even adulthood. Indeed, some natural predators are reintroduced for their protection, but at the expense of sea turtles. Moreover, this can also happen when natural predators suddenly become more numerous following human intervention.
The last line of defense against the disappearance of sea turtles: associations
There are dozens of associations fighting against the disappearance of sea turtles. Among them, the WWF actively works for conservation through numerous actions: firstly, the signing of a bilateral agreement between the Philippines and Malaysia with the aim of creating a Turtle Islands Heritage Protected Area. This is the very first protected area in the world specifically for marine turtles, and it also includes one of the two most important green turtle breeding and nesting sites in Southeast Asia. Moreover, the association does not hesitate to fund patrols for the protection of turtle nests and also works at the legislative level with governments to establish laws for protection. The WWF also helps to test and introduce new types of hooks, which are less harmful, and makes them mandatory in certain countries around the world. Finally, the association actively fights against poaching and seeks to establish alternative livelihoods so that local communities no longer depend on income generated by turtle hunting.
We hope you enjoyed this article about sea turtles and that it provided you with a lot of knowledge about these mysterious and majestic animals. If you would like to know more about animal life, you can also read our article on 10 questions we ask ourselves about horses.
