Leatherback turtles are the largest turtles alive today and their origins can be traced back over 100 million years. They have adapted uniquely well to life in the ocean and spend most of their time swimming and hunting for food. While they are one of 7 species of sea turtles, they are the fastest, largest, and deepest divers of any turtle species.
Unique physical characteristics
A leatherback turtle is quickly identifiable by its unique physical traits. These traits spawn from a completely aquatic lifestyle and have evolved to give the leatherback underwater prowess that lets them thrive in the ocean. The first thing most people notice about a leatherback turtle is its unique shell composition and massive size.
Leatherback turtles, much like softshell turtles, adapted to marine life by evolving a soft-shell instead of the traditional hard shell found on most species of turtles. The soft-shell serves many purposes and is essential to its unique aquatic lifestyle.
The soft-shell is typically black in color with white dots and is flexible and rubbery to the touch. Instead of the hard carapace made of keratin that most other turtle species have, these turtles possess an outer shell that is made up of cartilage-like tissue. The tissue is covered with an outer skin that is strong enough to sustain minor attacks while allowing flexibility that other turtles do not enjoy.
A soft-shell and more flexibility allow leatherback turtles to swim faster, and dive deeper than any other turtle. Leatherbacks can dive to depths of a recorded 4,200 feet. Sea turtles with traditionally hard shells can only dive up to 500 feet or so. This is because of decompression issues that arise due to the hard shell’s inability to absorb nitrogen.
Hardshell turtles who push past the 500-foot depths may experience decompression sickness similar to human divers who return to the surface too quickly. The leatherback turtle, who lacks a rigid breastbone, does not encounter these issues when diving deep or returning to the surface. This allows them to hunt for food in spaces where they do not have to compete with other turtles.
Size and weight
Leatherback turtles are truly massive. They are the heaviest turtle species in the world and can weigh up to 2,000 pounds. This means that it’s possible for a leatherback turtle to grow to be heavier than several models of compact sports cars. They typically grow to be around 6 feet long, and the longest leatherback was measured at 10 feet from the tip of its beak to the end of its tail.
They are the fourth heaviest reptile species in the world, which is impressive in and of itself. It’s more impressive when you consider that the first 3 reptiles on this list are all crocodiles that can grow to be 15 feet in length. The leatherback is the only turtle in the top 10 heaviest reptiles list with the tortoise coming in at number 11. Their massive size is even more impressive when you consider that their diet is made up of almost entirely jellyfish which have poor nutritional value.
Another adaptation for life in the water comes in the form of the turtle’s flippers. Whereas land-based turtles have feet to walk around on, the leatherback and other sea turtles evolved flippers to help them move quickly through the water.
A leatherback’s front flippers are quite long and adult specimens have wingspans of around 8 feet. The turtles use a flapping motion with their enormous front flippers that is similar to a bird flying through the air. This allows them to propel themselves through the water at speeds of up to 22 miles per hour. Other sea turtles are slower and have smaller wingspans. They typically max out around 6 miles per hour in the water.
The leatherback’s flippers cannot be retracted into their shell as seen on land-based turtles, so they are more vulnerable to attacks. Instead of using their shell for defense, they rely on the speed their flippers provide them with to outrun or outmaneuver predators.
The flippers located towards the rear of their shells do not provide additional speed or momentum and are used primarily as rudders. The hind flippers help to guide the turtle along smoothly and allow them to make rapid changes in direction. Hind flippers also serve as a tool when digging a nest on land or trying to uncover food from the ocean floor.
Leatherback turtles are the only species of sea turtles who do not possess some form of claw or hook on their flippers. These claws and hooks are used for mating and foraging purposes in other sea turtles, but the leatherback is still able to accomplish these tasks through other means.
Unlike most other species of turtles that boast powerful beaks, leatherback turtles have more delicate beaks that are suitable only for eating invertebrates. The diet of a leatherback turtle consists primarily of Jellyfish, and occasionally seaweed. When feeding, each leatherback turtle can eat it’s own bodyweight in jellyfish each day, which is around 16,000 calories or more. This is more than 5 times what is required to sustain themselves.
The reason that leatherbacks eat in excess comes back to their astonishing migration habits. When they are migrating, there is not enough time to stop and eat each day. To combat this, turtles eat far more than they need to and save the energy for migration to mating or nesting grounds.
The leatherback turtle lives in oceans all across the world. According to National Geographic, they have the widest global distribution of all reptiles, and potentially all vertebrates. These turtles can be found in the Atlantic, Pacific, and Indian Oceans, as well as the Mediterranean sea.
The leatherback is unique in its ability to thrive in both temperate and tropic waters. They can be found as far north as Canada, and as far south as South America. Leatherbacks have specialized adaptations that allow them to go in colder waters where other turtles would die from becoming “cold-stunned”. Reptiles, by nature, are cold-blooded and rely on the outside air or water temperature to heat them up.
These adaptations include a large body size to help retain heat, a thick layer of fat between their shell and body, and an adaption of their blood vessel system called a “countercurrent exchanger”. The countercurrent exchanger allows these turtles to move blood both in and out of their bodies towards and from their limbs at the same time. The blood running back into the turtle’s bodies is heated up by the blood that is on it’s way out, ensuring that they do not become cold-stunned like all other species of turtles would.
Migration and travel
While leatherback turtles are found in every ocean, they rarely stay put for a long period of time. Leatherbacks have areas where they feed, and areas where they mate and nest. These areas are often quite far from each other and make these turtles one of the longest migrating animals on earth.
The distance between feeding and mating grounds often requires migration of several thousand miles. Leatherbacks are strong swimmers and can travel upwards of 10,000 miles each year while looking for food or mating/nesting grounds. In the Atlantic, they have been recorded traveling from the Bahamas to northern Canada. In the Pacific, they can go from Southeast Asia to Alaska.
Leatherback turtles take 15 to 25 years to reach sexual maturity prior to nesting. Typically, they nest every 2 to 3 years as part of their migration. The nests are established on beaches where the female leatherbacks dig holes in the ground. They prefer to do this at night, and will not come ashore if there are too many artificial light sources on their chosen beach.
Once a nest has been dug, the female will lay 60 to 120 eggs, with only about 85% of them being viable and having the opportunity to hatch into baby leatherback turtles. A female leatherback will typically lay around 7 to 12 nests per season, meaning they dig new nests, and lay new eggs every 10 days in the period. This puts the total number of eggs a female leatherback can lay each nesting season around 420 to 1,400. This is the most eggs of any reptile known today.
Baby leatherback turtles
The incubation time of these eggs is typically around 60 days. The sex of the baby leatherbacks is determined by temperature. A warmer temperature during incubation will produce more females, and a colder temperature produces more males.
Once the eggs hatch, baby leatherback turtles have to make their way to the ocean without getting eaten by seagulls, crabs, and other reptiles on the beach. According to Leatherback.org, around 10% of baby turtles will not make it to the water, only 25% will make it through the first several days in the water, and only 6% will survive their first year of life. It is thought that this is the reason why females lay so many eggs.
Once the baby leatherbacks are in the water, they are hard to track. Scientists who study sea turtles refer to these as the “the lost years”, and not much is known about their first 10 years of life. It is thought that leatherback younglings stay in warm shallower waters that allow them to protect themselves against predators while hunting smaller jellyfish and other invertebrates.
During the early years of life, leatherback turtles have many predators to watch out for. When they are eggs, seabirds, raccoons, foxes, crabs, and dogs are known to go out of their way to dig up nests for a meal. Baby leatherback turtles face extreme opposition as well. Because they do not have hard shells like other turtles, any animal with a jaw strong enough to bite them will eat them. This includes carnivorous fish like groupers, snappers, and barracudas, as well as other reptiles and sea birds.
Even adult leatherback turtles, despite their massive size, are not immune to becoming prey themselves. Since they lack a traditionally hard shell even at maturity, their only options are to outrun or outmaneuver those who try to eat them. Once they’ve reached adulthood, a leatherback’s primary predators are sharks and killer whales.
Despite all of these threats, it is humans and human activity that are to blame for their inclusion on the endangered species list.
The leatherback turtle is currently listed as an endangered species under the Endangered Species Act. The National Oceanic and Atmospheric Administration (NOAA) estimates that the global population of leatherback turtles has declined by 40% in just the last 30 years. They blame several factors for the decrease in the leatherback population, all of which are caused by humans or human activity.
The biggest threat to the livelihoods of leatherback turtles is unintended damage caused by fishing activities. Large fishing nets will catch turtles and cause them to become tangled and disoriented. Even if they are able to break free, they are often damaged to the point where their survival is no longer probable. Turtles will sometimes also bite at fishing lines which can become lodged in their throats rendering them unable to eat.
Another major threat to their existence is egg poaching by humans. Despite leatherbacks being protected by several governments, citizens continue to poach nests for turtle eggs. These eggs are collected and eaten by people for nutrition and are also seen in some cultures as a powerful aphrodisiac. Whatever the reason, human egg poaching is a leading cause of the species decline.
Pollution of our oceans is rampant and sea turtles are directly impacted. Leatherbacks and other sea turtles will eat quite a few forms of pollution that they mistake for food. Plastic bags look like jellyfish to them, and they have also been known to eat discarded fishing lines, balloons, and microplastics. All of these can cause the death of a sea turtle in large enough quantities.
Save the sea turtles!
Leatherbacks and other species of sea turtles have existed for millions of years and were stable or growing in population until human pollution and fishing activities intervened. While leatherback turtles specifically have lost 40% of their population in the last 30 years, the rates for other species of sea turtles are even higher.
Thankfully, there are organizations such as the National Save the Sea Turtle Foundation, the World Wildlife Fund, and SeeTurtles.org, that are actively working to combat the damage done to this unique species of turtle. Visit their websites to learn more about the efforts that are being made, and to learn how to help the cause.