The Leatherback Sea Turtle

The Oceans Ancient Giant
(Dermochelys Coriacea)
By: Ardea Batiste

The leatherback sea turtle is the oldest and biggest of sea turtle species, and it is in imminent danger of extinction. This sea turtle is extremely unique, mysterious and powerful.  Because of its migratory nature, they have been found traveling all over the world's oceans, with a range so vast that scientists have found it challenging to study them.  Until recently, the leatherback has thrived throughout the oceans since the time of the dinosaurs. Since the 1970's, the Leatherback population has been in decline.  Presently, they are critically endangered because of changes in habitat, pollution, and current fishing practices. If nothing changes, it is estimated that this species will face extinction in the next 20 years.  So what makes them so distinct? And why after so long are they now endangered? 

Appearance:

Comparison of Different Sea Turtles 

The leatherback sea turtle is the largest and most unique of all sea turtle species. These huge, ancient creatures can reach over six feet tall and weigh as much as 2,000 pounds.  With a flipper span up to 3 meters (9.85 feet), their front flippers are paddle shaped, clawless, and proportionally larger then other sea turtles. The leatherback is the only sea turtle that doesn't have a hard bony shell, which is one of the most distinguishable aspects of this species of turtle.  Instead, they have a thick, tough layer of hard, leathery, scaled skin covering a framework of dermal bones.  This leathery shell characteristic is where the leatherback sea turtle gets its name.  They have seven ridges running lengthwise along their back, which are usually black, but may be dark brown or dark grey, with a varying amount of pinkish white spots.  Their underside is mottled pink, white and black, with adult females having a characteristic pink pontoon on their head. They have two down curved projections on their upper jaw, and their lower jaw is hooked backwards. (The picture to the right shows the leatherback’s differences in appearance in comparison to other sea turtles.)

Prey:

Inside of a Leatherbacks Mouth 

Leatherbacks primarily feed on jellies, but are also known to eat crabs, fish, sea urchins, squid, crustaceans, tunicates, algae and seaweed.  They can dive to depths of up to 1,000 meters (3,300 feet) in search of food.  This depth was recorded by turtles wearing satellite telemetry devices.  Only two other air breathing species are known to surpass this remarkable diving depth:  the sperm whale and the elephant seal.  With a diet consisting mainly of not particularly nutritious jellies, the leatherback must eat almost its entire weight in jellies each day.  In order to digest this large amount of food, the insides of their mouth (all the way to their stomach) is lined with spikes.  These spikes break down the food as it is being swallowed, and makes the inside of the leatherbacks mouth a truly terrifying sight. (You can see this in the picture to the above) Leatherback turtle feeding (start at 0:20)

Taxonomy:

Kingdom: Animalia

Phylum: Chordata

Class: Reptilia

Order: Testudines

Family: Dermochelyidae

Genus: Dermochelys

Species: coriacea

The leatherback sea turtle is the only species left in the Dermochelyidae family, with all other species that were once part of that family now extinct.  With its evolutionary roots tracing back to thxe age of the dinosaurs, this ancient species has been on earth far before humans.  This ancient species is the last remaining member of a family that has existed for over 100 million years. Presently, all other sea turtles are part of the Cheloniidae family, classified by the similar characteristics of their small, hard shell.  The leatherback is classified separately because of the unique appearance and structure of their outer shell.  However, the leatherback is similar to the species of the Cheloniidae family in behavior, and has shown similarities in both morphological and biochemical studies. 

Life History:

The leatherback sea turtle lives a long life traveling through the ocean waters.  Their exact life span is not known for certain.  Some scientists conclude that these sea turtles can live as long as 100 years, while others have a lower prediction of a thirty year life span, but it is most commonly believed that they live approximately fifty years.  Along with the uncertainty of the leatherbacks life span, there is also a discrepancy as to when they reach sexual maturity.  Many scientists estimate sexual maturity between the ages of six and ten.  However, others believe that it is as late as sixteen, or as early as three years old.  

Nesting Leatherback

Once mature, females and males breed in the ocean every 2-3 years.  Like most sea turtles, leatherbacks make their nests on sandy beaches. But unlike most sea turtles who nest during the spring and summer months, leatherbacks nest in fall and winter.  When the female is ready to lay her eggs, she pulls herself up the beach and digs a nest for herself.  Leatherbacks usually nest during the night and return to the ocean in the morning, but this is not always the case.  After she lays her eggs, she covers the nest with sand, makes a large disturbed area to conceal the nest from predators, and returns to the ocean.  Female leatherbacks can lay anywhere between 1-11 clutches of eggs per season.  Each clutch can contain 50-100 fertilized eggs, and within 55-75 days later, the babies begin to hatch.  

Click this link to watch a mother leatherback laying her eggs.  

Leatherback Hatchlings Emerging From Their Nest

The task of emerging from the nest is not easy for the hatchlings. The whole group works together to break free.  A process that can take several days.  These hatchling are 2-3 inches in size, which is a remarkable reality considering the giant size they will grow to become when fully mature.  Hatchlings are also black with light spots like their elders.  

Leatherback Hatchling

 Yet, unlike the scaleless skin of the adult leatherback, hatchlings are born covered in small beadlike scales.  Once they break free from the nest, they must make their way to the ocean.  In order to find the ocean, they orient themselves with the bright reflection of sun on the water.  This journey from nest to ocean is very difficult, and many of these vulnerable hatchlings do not survive due to a variety of reasons, such as predation or simple exhaustion.  The hatchlings that survive the trek to the ocean, remain in warm tropical waters until they have grown enough to survive colder waters. 

Click this link to watch leatherback hatchlings make their way to the ocean.

Adult Leatherback Swimming

Geographic: 

Leatherback sea turtles are the most migratory reptile, and one of the most migratory animals,  traveling more then 16,000 kilometers (10,000 miles) each year in search for food.  This vast migration pattern makes them very hard to study, which is not helped by the fact that they do not survive in captivity.  The leatherback sea turtles' range is hard to define because of how migratory they are. Leatherbacks are known as pelagic (open ocean animals), but they can also be found foraging for food in coastal waters.  This vast range is possible because of the leatherbacks’ insulant abilities, allowing them to survive in colder water then any other sea turtle. 
Swim with a leatherback sea turtle (Start video at 0:50)

Population:  

The male turtles may never return to land after they hatch, and the females only return to lay their eggs.  This makes finding an accurate estimation of their population very challenging.  There is no estimate on the size of the male leatherback population, but it is estimated that there are approximately 20,000 - 30,000 nesting females alive today ("Leatherback Turtle." WWF).

Number of Leatherback Nests at Jamursba Medi, Indonesia 

Since the 1970s the leatherback population has been in a steady decline.  The Pacific Leatherback population is declining faster then the Atlantic Leatherback population, but scientists believe that the Atlantic population will begin to decrease at a faster rate. It is estimated that overall, the global population of leatherback sea turtles has declined approximately 40% over the past 3 
generations (Wallace). The Graph above shows this decline at a popular nesting beach in Indonesia.  This is just one example but most beaches show a similar decline. 

Listing Date and Type of Listing:

The leatherback sea turtle was listed as endangered throughout its entire range under the Endangered Species Act (ESA) on June 2nd, 1970.  This means that it is protected wherever it is found in nature.  In 1982, it was also listed as endangered on the International Union for Conservation of Nature (IUCN) Red List.  In the year 2000, the listing was raised from endangered to critically endangered on the ICUN red list. 

• Listed as endangered under the ESA in 1970

• Listed as endangered under the IUCN Red List in 1982

• Listed as critically endangered under the IUCN Red List in 2000

Main Threats:

Leatherback Sea Turtle Drowned in Fishing Equipment 

The main threats to the leatherback population are: 

• Coastal Habitat Loss

• Predation by Feral and Domestic Animals

• Incidental Catch or Bycatch

• Light and Chemical Pollution

• Entanglement and Ingestion of Debris

• Egg Poaching and Disturbance of Nests

Most wild animals face the danger of habitat loss, and a large number of these animals have also been hunted for various  resources.  The leatherback is no exception to being exposed to these dangers, and it is because of humans that their population is in grave danger.  The increase in human activity on the beach, both recreational and commercial, restricts the amount of safe nesting habitat.  The risk of nest disturbance and the crushing of nests increases with the growth in the human population.  Nests are vulnerable to these following situations, all influenced by the presence of humans: vehicular driving on beaches, beach construction, and predation by domestic animals.

Presently, the single greatest threat to the leatherback population is incidental capture by commercial fisheries.  Incidental capture, also called bycatch, is where non-target animals are caught in fishing equipment.  These animals often die and are discarded back into the ocean.

Longline

Gill-Net

Two of the worst commercial fishing strategies are: the gill-net, the longline.  These fishing strategies are non-selective, which results not only in the mass capture of fish, but also in the un-necessary death of many marine animals. This is especially a problem for species who already have greatly depleted populations, such as the leatherback.  Although the leatherback can hold its breath for up to five hours while resting, this amount of time is greatly shortened when they are active under stress.  Thus, getting caught in fishing equipment puts a great strain on the animal as they struggle to free themselves, which causes them to drown relatively quickly. Hundreds of leatherback turtles drown annually because of these non-selective fishing methods. Other methods of commercial fishing are available.  The purse seine, for example, is only responsible for 1% of the worlds total bycatch.  In order to protect the heath and function of the marine ecosystems, and animals like the leatherback, it is essential that the use of non-selective fishing gear stops. 

Light pollution is another issue.  I mentioned before how the hatchlings orient themselves with the ocean, by looking at the bright glare of sun on the water.  The increase of human made light along the edge of the beach can disorient the hatchings causing them to orient inland.  This way they never find the ocean and are either crushed by cars, eaten by predators, or they simply die of exhaustion and exposure. 

Jelly V.S. Plastic Bag 

The increase of debris in the ocean causes two problems for these sea turtles.  They can get caught in large amounts of debris, such as abandoned fishing equipment, or they can ingest harmful trash.  Fishing equipment tangled around the turtles, can permanently bind around a part of their body causing deformity as they grow.  This can inhibit movement and ultimately decrease chances of survival.  Plastic bags look very similar to jellies, and animals who feed primarily on jellies, such as the sea turtle, often eat plastic bags by mistake.  The ingestion of plastic is not good for any living creature.  If enough plastic is eaten, it can clog their digestive track and cause them to starve to death.  The chemicals in this waste can also cause sea animals to become sick.

The main cause of the leatherback’s currently diminished population is egg poaching. Egg poaching is less of a problem now, then it was in the past, but it is still considered a problem for the leatherback sea turtle.  Their population was greatly weakened in the past when almost 100% of their eggs would be harvested each year.  

Recovery Plans:

In 1992, and again in 1998, the ESA created two recovery plans for leatherback sea turtles.  The first addressed the recovery of the species in the U.S. Caribbean, Atlantic Ocean and Gulf of Mexico.  The second addressed the recovery of the U.S. Pacific populations of leatherback sea turtles.  The goal of these plans was to delist the species.  In order to delist a species, a set of criteria must be met, insuring that the species is no longer in danger.  Both recovery plans work to protect nesting habitats, marine habitats, and the populations within these habitats.  As part of ESA's recovery plan, they also address how to best work with other countries where the leatherbacks live. 

Protecting Sea Turtle Nests

These recovery plans work to eliminate or reduce the threats to the species.  The ESA acts on a plan through a few major actions such as: informing the public about these threats and what they can do to help, creating and enforcing laws and regulations to further protect the species, and by working to help other countries in their efforts to help.  Unlike some species that can be bred in captivity, the leatherback species does not survive well in captivity.  However, trained professionals have been successful in collecting eggs, hatching them in incubators and then releasing the hatchlings back into the ocean.  This helps to give the young ones a head start.  The work done by the ESA has helped in many ways but this species population is still declining and in need of further assistance.

Personal Action:

Don't Trash the Ocean

With all of the talk about impending extinction and threats to the existing population, it feels good to know that there is something that we can do it help this species that desperately needs our help!  There are many things that individuals can do to help, from simple actions to things that might make take more time. Some of these contributions are the following:

1.  Reduce the amount of trash you make

When you throw things away, they don't just disappear! A lot of this waste actually ends up in the ocean; and much trash, like plastic, may never decompose.  Thus, switching to using paper (which does decompose), or reusing plastic produce/grocery bags, will prevent turtles from coming into contact with plastic and mistaking this discarded waste  as  jellies.  Buy a reusable water bottle, or reuse another bottle (glass Snapple bottles are a good option).  Recycle what you can, so it gets reused instead of dumped into landfills or water sources.  Simply, do anything else you can to reduce the amount of trash you produce.

2.  Watch the Amount of  Chemicals You Use

Everything is connected.  If you spray pesticides on your plants, you may never think they will end up in the ocean, but they can and do.  Similarly, chemicals in cleaning supplies can end up in the ocean through plumbing and sewage. Chemicals that make their way to the ocean can be ingested by small organisms, who are then ingested by bigger ones, and in this way they work their way up the food chain.  Each species up the food chain eats many of the species below them, and incidentally the amount of chemicals magnifies in each species until they become dangerous. This is called Bio-magnification.  So make sure you are using household and gardening products that are environmentally friendly. 

3.  Support Organizations

There are many organizations that are working to help save endangered species, such as the leatherback sea turtle.  These organizations work to help eliminate bycatch, create safe nesting cites, end poaching, and protect critical habitat.  These organizations often support or implement research on the best ways to help these endangered species.  A few of the organizations that work to help protect wildlife are:

• World Wildlife Organization (http://www.worldwildlife.org)
• Wildlife Conservation Society (http://www.wcs.org) 
• U.S. Fish and Wild Life Service (http://www.fws.gov)               

4. Help Reduce Light Pollution

If you live close to a beach, minimize beachfront lighting on nesting beaches during the nesting season by turning off lights, shielding them or directing them away from the beach and by closing blinds and drapes in oceanfront rooms.  If you do not live on a nesting beach, you can send a letter to large beach side establishments or the government official in charge of that area, informing them of the importance of reducing light pollution.

5. Pass This Information On

Don’t let this stop here!  Pass on what you have learned and help spread the word about the dangers this species face and what you can do it help!

Everyone Needs a Snuggle Buddy:)

Sources Cited:

"Leatherback Turtle (Dermochelys Coriacea)." :: NOAA Fisheries. N.p., 11 June 2015. Web. 06 Dec. 2015.

Recovery Plan for U.S. Pacific Populations of the Leatherback Turtle (Dermochelys Coriacea). Silver Spring, MD: U.S. Dept. of Commerce, National Oceanographic and Atmospheric Administration, National Marine Fisheries Service, 1998. U.S. Fish & Wildlife Service. 2 June 1998. Web.

Lewison, Rebecca L., et al. "Global Patterns Of Marine Mammal, Seabird, And Sea Turtle Bycatch Reveal Taxa-Specific And Cumulative Megafauna Hotspots." Proceedings Of The National Academy Of Sciences Of The United States Of America 111.14 (2014): 5271-5276. Academic Search Complete. Web. 30 Nov. 2015.

"Leatherback Sea Turtles." Dermochelys Coriacea." MarineBio.org. MarineBio Conservation Society, 29 May 2013. Wed. 01 Dec. 2015

"Sea Turtle Migration." SEETurtles.org, n.d. Web. 02 Dec. 2015

"Leatherback Turtle." WWF. World Wildlife Fund, 2015. Web. 02 Dec. 2015

Wallace, B.P., Tiwari, M. and Girondot, M. 2013. Dermochelys coriacea. The IUCN Red List of Threatened Species. Version 2015.1. Downloaded on 02. Dec 2015.

None of these images are mine. All photos were found on google images