Deep Sea News

Wallace J. Nichols is a sea turtle biologist and marine conservation activist affiliated with the California Academy of Sciences, Ocean Revolution, and the Sea Turtle Network, among others. J’s blog is dedicated to new beginnings and fresh ideas, especially among young people.

Green turtles mating in Sipadan, Malaysia. Photo by Petter Lindgren at Flickr.

There should be a sign posted along beaches of the world during a certain season: “WARNING: Enter water at your own risk”.  I’m not speaking of extreme undertow or heavy shore-break.  Not water quality, or red tide concerns. Nor warnings against poisonous jellyfish.  These are all important water safety concerns, but I am referring to something else, something almost as dangerous. I am talking about the distinctly unique experience of being in the water with green turtles during mating season.

On a recent research expedition to Indonesia, we had the opportunity to sneak up on a pair of mating green turtles. It’s a sight to behold for its grace, beauty, ancient simplicity and…well, its ruggedness.

Green turtle mating happens in the water.  Often in beautiful turquoise tropical water, near idyllic sandy beaches backed by bent palm trees.  Add a Barry White soundtrack and a couple of mai-tai’s and it’s honeymoon city.

A bit of an aquatic turtle dance precedes copulation.  Males nip and bump and eventually mount the female.  To a biologist, it’s kind of like watching two boulders with flippers getting it on.  Other than the female guiding the rigid ball of turtle to the surface to breath, there’s not much apparent movement during the act. Throughout the mating season males maintain high activity levels, presumably associated with locating and mating with as many females as possible to maximise their reproductive output (Hays et al., 2001).

The male turtle hangs on to the front edge of the female’s shell with a pair of large recurved claws.  The male’s tail has another “claw” at the end.  This facilitates a sturdy three-point attachment, whereby the penis can enter the cloaca of the female.  Attempts to knock male #1 off of the female turtle by males #2 through 17 are frequent, severe and generally unsuccessful.  Physical damage to both members of the copulating pair is common.

Occasionally, a horny, excluded male will mount the pair (this is going absolutely nowhere for male #2).  Further on, another male may join the fun and attach his tripod of claws to male #2.  So on and so on, as a chain of turtle love and hormones extends to four or more.  When this sort of thing happens with earthworms in the garden, it’s merely curious.  With 400 pound sea turtles its a bizzarely orgyastical circus of ancient oceanic sexuality.  Bring your camera.

But it gets better.  Male turtles are known to hang on (and in) for hours on end.  For 2, 8, 12 hours…or more.

Through the years, this has been impressively noted by the males of the human species.  I’m willing to bet this is somehow related to the belief that turtle eggs are aphrodisiacs beyond compare.  Incidentally, and perhaps not unexpectedly, the dried and shaved green turtle penis is considered wickedly potent when added to booze, a sort of Viagra with King Kong strength.  First hand experience tells me that neither are particularly effective.

Back in the ocean, males are the pursuers, the females are the deciders.  An unreceptive female will press rear flippers together and/or rest on the sea floor, prohibiting access to her cloaca and eggs.  That leaves the males swimming in circles around her, biting each other, mounting each other, mounting logs or buoys or…(back to the warning signs on the beach)…you.

A horny male green turtle will aggressively mount a swimmer, snorkeler or diver.  Expect a big claw on each shoulder and a large tail around underneath.  Attached to 400 pounds of reptile ready for some all day and all night lovin’.  Consider yourself warned.

Cue soundtrack, Marvin Gaye,  “Let’s get it on“…and on, and on, and on….

Citation:

Hayes, G.C., Broderick, A.B., Glen, F., Godley, B.G., & Nichols, W. J. (2001). The movements and submergence behaviour of male green turtles at Ascension Island Marine Biology, 139 (2), 395-400 DOI: 10.1007/s002270100580

FU Penguin give sea turtles a piece of their mind.

You know, when sea turtles look at me like that when I’m snorkeling I feel the same way. I mean come on turtles! Stop being so judgmental! Just trying to have a good time… sheesh. Lighten up a little.

Deep Sea News is proud to present the Iron Turtle award in partnership with Conservation International and National Geographic. The official press release follows.

Academic judges from Deep Sea News have declared a 340 kg leatherback turtle named Cali to be this year’s Iron Turtle award winner in the Great Turtle Race 2009. The results are a surprise to race fans.

Cali, sponored by the Bullis Charter School in Los Altos, California is a small turtle compared to the larger, more experienced competitors in this year’s Great Turtle Race.  He fell behind in the > 6,000 km oceanic marathon, even failed to place, but strong performances in the diving competitions resulted in an overall victory for Cali; his coach, US Olympic swimmer Eric Shanteau and all his supporters at Bullis are overjoyed.

Cali completed 148 dives longer than one hour, and he dove deeper than 800 m on five separate occasions during the marathon, thereby securing first and second place in these two events.  For comparison, the world record human free-diver, Sara Campbell, dove to a mere 96 m only one time and only for 3.5 minutes!

“Hats off to Sara Campbell of course, but these turtles are really built for long-lasting, deep dives” said Bryan Wallace, Conservation International scientist and Deep Sea News contributor. “Cali showed some remarkable ability in these events, especially in an impressively talented field.”

The Iron Turtle is a “triathlon” event consisting of the marathon race, the deep diving event, and the long diving event.  Pearl Jam’s turtle, Backspacer, won the gold in the marathon, followed by Seabiscuit and Nueva Esperanza for silver and bronze.  The scoring system used by Deep Sea News judges was based on USA Swimming rules, awarding 5 points to first place, 3 points to second, and 1 point to third place.

Deep Sea News blogger Peter Etnoyer said, “Our mission is to promote awareness of the deep-sea and the animals that live there. The Iron Turtle competition was the perfect way to be a part of the Great Turtle Race, and to celebrate these endangered turtles.”

Cali, an adult male leatherback, was unique among his competitors because when researchers from the Canadian Sea Turtle Network (www.freetheleatherback.com) first found him prior to the Race, he was entangled in fishing gear. After the Canadians freed him, he was off to the races with the other turtles, but his ordeal is a reminder of the many threats that leatherbacks and other marine animals face in today’s oceans.

“Cali faced and survived a very serious threat that many of his turtle brethren fall victim to,” commented Roderic Mast of Conservation International, race co-organizer, “but he kept on swimming, like turtles always do, and even got a very prestigious award for his troubles.  Congratulations to all the turtles, their coaches, the staff, and the sponsors for making this year a truly “great” turtle race.”

A very special thanks to blogger Jason Robertshaw of Cephalopodcast.com for his design and contribution of the magnificent Iron Turtle Award.

Leatherback Sea Turtle. Image used with permission ©2009 Brian Skerry / National Geographic.

It has been an unofficial Turtle Week here at Deep Sea News with all the excitement surrounding the Great Turtle Race! The winner has been announced and the race is over. Wait? Can’t get enough turtle? You got a fever and the only cure is more turtle? National Geographic has just the thing!

Pick up the May issue of National Geographic Magazine and check out there feature article on Leatherback Sea Turtles with stunning photography by Brian Skerry. Check out the story by Tim Appenzeller online at Ancient Mariner: The biggest, deepest-diving, widest-ranging of all turtles, the leatherback has endured for 100 million years.

© Jean-Yves Georges - Great Turtle Race competitor "Wawa Bear"

Pearl Jam’s “Backspacer” is declared the victor in the Great Turtle Race, the first leatherback sea turtle to arrive in the Caribbean Sea from foraging grounds off Nova Scotia, Canada. The largest turtle in the race, Wawa Bear (pictured), was not the first place winner but she’s stirring the news because the 1200 pound behemoth arrived on the shores of French Guiana to lay 95 billiard-ball sized eggs.

“She is one of the biggest turtles we have ever weighed in French Guiana,” says Dr. Jean-Yves Georges. “She weighed 50 percent more than our average nesting turtles!””

“Our research has shown that turtles tend to be 33 percent heavier in Canada when they are bulking up on jellyfish than on the nesting beach after their migration,” adds James. “That would have put this turtle over 700 kilograms—more than 1,500 pounds—when we worked with her in the summer.”

Wawa Bear nested three more times since first being spotted. To see a schematic graphic comparing Wawa Bear to other leatherback turtle contestants, see Bryan Wallace’ DSN story Gigantothermy: Size Matters.

by Bryan Wallace for Deep Sea News

When you think of cold marine environments, you probably think of blubber-wrapped seals, whales, and walruses, big, furry bears, or a huddled mass of penguins. What do those animals have in common? They are endotherms, their body temperature maintenance depends on consistently high levels of heat generated (and retained) internally.

Animals you probably do not identify with cold conditions are reptiles. Generally speaking, reptiles (e.g. lizards, snakes, and turtles) are ectotherms, meaning that their body temperatures depend on ambient temperatures, such that reptiles in fluctuating thermal environments must behaviorally seek microclimates that will best suit their physiological needs. Thus, because they rely on heat from their surroundings, reptiles typically don’t handle cold environments very well.

In the 1960s, marine biologist Sherman Bleakney collected fishermen’s anecdotes, observations, and specimens of noteworthy large-bodied marine animals in frigid Nova Scotian waters. However, the fishermen weren’t telling stories about the grey seals or the minke whales. The tales were about turtles. Big turtles.

Bleakney and others had heard about the rotund, inky-blue turtles called leatherbacks occasionally reported in Nova Scotia, but considered them rare visitors that inadvertently appeared in these fog-coated cold waters. But once he put together all of the records, he realized that these critters were not lost; they were regulars.

Leatherbacks are extraordinary for many reasons, but perhaps their most impressive characteristic is their expansive distribution. They have the widest geographic and thermal range of any reptile species. Their tolerance of cold water allows them to exploit highly productive marine foodwebs at high latitudes and extreme depths that are unavailable to other sea turtle species. The fundamental question that Bleakney and others asked was: how can these turtles go where no other reptiles would dare?

Some pioneering work in the 1970s established that leatherbacks were able to maintain elevated and relatively consistent body temperatures in cold water (Frair et al., 1972). This was straightforward and not necessarily surprising given the observations in Nova Scotia, but the finding presented a significant challenge for the endotherm-ectotherm dichotomy: leatherbacks are turtles, but turtles are reptiles, and reptiles are not supposed to be able to generate and retain heat over long periods of time, especially in cold water. So how do leatherbacks it? Were they mammals in a turtle’s body?

With this question in mind, Jim Spotila and Frank Paladino hit the beaches of Costa Rica in the 1980s to solve the riddle of leatherback thermoregulation. While fending off hoards of bloodthirsty mosquitoes, sneaky scorpions, and earth-rumbling thunderstorms, they discovered that leatherback metabolic rates were much lower than those of mammals, but slightly higher than those of reptiles sized to leatherback size.

Frank Paladino in his field 'laboratory' using a Scholander respirometry apparatus to measure leatherback metabolic rates from turtle breath.

Using these metabolic rates in biophysical models, Paladino et al. (1990) figured out that leatherbacks could combine these relatively low, but consistent, metabolic rates with their huge body mass, a thick layer of peripheral fat for insulation, and adjustments in blood to stay warm in cold Canadian waters and to avoid overheating in toasty tropical Caribbean waters.

Because leatherbacks do not fit neatly into either the ectothermy or endothermy categories, their unique integration of heat generation and retention adaptations earned them a different term: “gigantotherms.”

A recent review of sea turtle metabolism and thermoregulation confirmed that leatherback metabolic rates are not significantly different from those expected for leatherback-sized reptiles, and that large body size is crucial to heat retention (Wallace and Jones, 2008). Leatherbacks can alter swimming behavior to increase heat generated internally through vigorous swimming (Bostrom and Jones, 2007), or by shuttling between different water temperatures to regulate heat loss, but their reptilian metabolic rates mean that being huge is necessary to avoid losing body heat. In fact, researchers have determined a body size threshold (~100 cm carapace length) below which leatherbacks are unable to penetrate water temperatures colder than 26°C, which means that to get in to the cold water habitats, big bodies are required (Eckert 2002).

Leatherbacks’ considerable girth is important for staying warm, but does it continue to their deep diving prowess? In general, for an air-breathing diver, buoyancy decreases as an animal gets bigger, such that really small sea turtles have to work harder to overcome positive buoyancy near the surface, but adult turtles can power down more efficiently. Additionally, large body size can mean higher oxygen stores in blood and muscle, facilitating longer and deeper trips beneath the ocean’s surface away from the turtle’s next breath.

Great Turtle Race 2009 contestants scaled by weight.

However, these size-based differences in diving and thermoregulation appear to disappear after the 100 cm threshold, as Searcher (the smallest turtle in the Great Turtle Race) showed with a very respectable finish in the Cold Water Challenge. The Iron Turtle competition should also bear this out. There is no size advantage for extreme diving – stay tuned to www.GreatTurtleRace.org to find out more!

Large-bodied leatherback turtles are gigantotherms because they integrate physiology, anatomy, and behavior to be able to forage in waters cold enough to kill a human in a matter of minutes, something no other reptiles on the planet can do.

At least no living reptile…

Leatherbacks are not the Earth’s only gigantothermic reptiles; dinosaurs employed the same mechanisms to range from the tropics to temperate latitudes during their heyday.

So at least now you know that size most definitely matters to turtles, particularly if you are a leatherback doing an impression of polar bears or penguins…

Citations:

- BOSTROM, B.L., JONES, D.R., 2007. Exercise warms adult leatherback turtles. Comp. Physiol. Biochem.,Part A 147, 323–331.
- ECKERT, S.A., 2002. Distribution of juvenile leatherback sea turtle Dermochelys coriacea sightings. Mar. Ecol. Prog. Ser. 230, 289–293.
- FRAIR, W., ACKMAN, R.G., MROSOVSKY, N., 1972. Body temperature of Dermochelys coriacea: warm turtle from cold water. Science 177, 791–793.
- PALADINO, F.V., O’CONNOR, M.P., SPOTILA, J.R., 1990. Metabolism of leatherback turtles, gigantothermy, and thermoregulation of dinosaurs. Nature 344, 858–860.
- WALLACE, B., & JONES, T. (2008). What makes marine turtles go: A review of metabolic rates and their consequences Journal of Experimental Marine Biology and Ecology DOI: 10.1016/j.jembe.2007.12.023

An article by Bryan Wallace for Deep Sea News.

The deep-sea is as far removed from atmospheric oxygen as anyplace on Earth, but a select few air breathers are undeterred. (No, I’m not referring to intrepid deep-sea human researchers.) These extraordinary critters frequently venture into the deep-sea, despite their vital link to air the above the ocean’s surface.

Colossal sperm whales plunge over 1,000 meters to battle giant squid in the dark abyss. Massive elephant seals chase prey more than an hour at depths > 1000 m. The deepest known divers are the beaked whales, with recorded dives to over 2,000 meters. What about turtles? Could a shelled reptile be suited for making dives where only a few whales and seals dare to go?

Leatherback turtles possess remarkable adaptations for long and deep dives. They have large onboard stores of oxygen in their blood and muscle, and special features like collapsible lungs (to avoid ‘the bends’), a pulmonary sphincter (to shunt blood flow away from the collapsed lungs and back to the body during dives), flexible shell (to respond to increased pressure at depth), and slowed heart rate (to conserve energy and oxygen stores). In fact, researchers have recorded leatherbacks diving to over 1,000 meters in different ocean basins (Doyle et al. 2008). Apparently, anything a whale can do, a turtle can, too.

Here’s a link to a National Geographic interactive showing leatherbacks’ anatomical and physiological adaptations for deep diving.

To be clear, leatherbacks spend most of their time within the top 300 m of the ocean. This is because they feed primarily on jellyfish, like lion’s mane jellies and sea nettles, which tend to be concentrated at or near the ocean’s surface (James et al. 2005). However, leatherbacks are clearly capable of – and undertake – much more ambitious diving. The obvious question is: what are leatherbacks doing down there?

At this point, we aren’t sure what motivates a leatherback to plunge thousands of meters away from their most critical resource, but there are a few possibilities. Like other deep-divers, they might be pursuing prey. (Let’s face it; food is a strong incentive for any animal.) Perhaps they shuttle between different water temperatures in order to keep their body temperature stable, so an occasional deep dive into frigid waters could offset the heating effects of strenuous diving. Or maybe, like many other marine animals, they use the deep-sea as refuge to evade hungry predators, such as sharks and orcas.

A recent study by researchers in the UK (Houghton et al. 2008) examined several hypotheses about why leatherbacks perform such extraordinarily deep and long-lasting dives using satellite transmitter-derived dive data. Their analyses led them to infer that these occasional sojourns to the deep are essentially to have a look around. Leatherbacks seem to use these deep dives as a way to scan the water column, potentially relying on chemical cues to orient themselves to potential food resources or oceanographic features.

What we know for certain is that leatherbacks are certainly unique among sea turtles in their special abilities reach profound depths and stay down for extended periods of time. These adaptations reveal evolution’s power and elegance because they converge so strongly with analogous adaptations in distantly related taxa like cetaceans, pinnipeds, and diving birds.

While leatherbacks have yet to reveal all of their secrets to us, hopefully our current efforts and those of our colleagues in other parts of the world will shed light on the dark side of leatherbacks’ deep-sea lives.

In the Great Turtle Race, we are using satellite telemetry to track male and female leatherback turtles migrating from feeding areas off Nova Scotia, Canada to breeding areas throughout the Wider Caribbean. Check out www.GreatTurtleRace.org to follow leatherbacks on their migration and to learn more about leatherbacks, the threats they face, and what is being done to protect them.

Given the leatherbacks’ superlative diving abilities, we are highlighting special swimming performances by leatherback turtles during the Great Turtle Race – the categories are 1) most deep dives, and 2) most long-lasting dives. These should be of particular interest to the DSN’s readers. The turtle who best proves its diving mettle will be crowned the ‘Iron Turtle’ by DSN at the end of these diving competitions.

Go to the GTR website to meet the turtle competitors, pick your favorite, and check in daily to GTR and DSN for updates on the Iron Turtle Competition!

Citations:

Doyle, T., Houghton, J., O Súilleabháin, P., Hobson, V., Marnell, F., Davenport, J., & Hays, G. (2008). Leatherback turtles satellite-tagged in European waters Endangered Species Research, 4, 23-31 DOI: 10.3354/esr00076

Houghton, J., Doyle, T., Davenport, J., Wilson, R., & Hays, G. (2008). The role of infrequent and extraordinary deep dives in leatherback turtles (Dermochelys coriacea) Journal of Experimental Biology, 211 (16), 2566-2575 DOI: 10.1242/jeb.020065

James, M., Myers, R., & Ottensmeyer, C. (2005). Behaviour of leatherback sea turtles, Dermochelys coriacea, during the migratory cycle Proceedings of the Royal Society B: Biological Sciences, 272 (1572), 1547-1555 DOI: 10.1098/rspb.2005.3110

We might as well call it Turtle Week at DSN. The Boss suggested we put together a few highlights from DSN stories that rolled out over the years, presented here in chronological order. Keep your eyes peeled for fresh news and interviews from the Great Turtle Race in coming days.

Sea turtle advocates appeal to the Vatican
http://deepseanews.com/2007/03/sea-turtle-advocates-appeal-to-the-vatican/

Easter is a difficult time for turtles in Mexico because of the Lenten tradition of eating turtles and their eggs. Sea turtle advocates are calling on the Pope to explain that sea turtles are not fish, while enlisting supermodel Dorismar to explain turtle eggs do not make you sexy.

Leatherback turtles: one year later
http://deepseanews.com/2008/04/leatherback-turtles-one-year-later/

Bryan Wallace answers the question “whatever happened to that big old turtle,” in reference to the most famous turtle picture ever at Deep Sea News. This story made the rounds. By the time Bryan wrote this article, the original post had accounted for 25% of DSN recent daily visitors, with 100 comments to date.

The cave where turtles die
http://deepseanews.com/2008/07/the-cave-where-turtles-die-video/

A classic noir film in the turtle genre. Voila mystique.

More sea-turtles nesting on Texas beaches
http://deepseanews.com/2008/08/more-sea-turtles-nesting-on-texas-beaches/

A reminder that not all turtle news is bad news. Texas turtles are on the rebound after years of neglect, thanks to natural, protected nesting beaches and shrimp trawl net modifications.

Satellite tracked sea turtle swims in Google Ocean
http://deepseanews.com/2009/02/satellite-tracked-sea-turtle-swims-in-google-ocean/

A recent fly-thru video of Adelita’s migration across the North Pacific viewable in Google Earth. Adelita was J Nichol’s first tagged turtle. She traveled two years from Baja California to Japan, then disappeared. J is a friend and colleague, you can read his blog here.

This originally posted here during Megavertabrate Week in 2007. I’m reposting it here in honor of the Great Turtle Race of 2009! Good luck turtles! See map below for updated results – Billy is swimming like crazy!.

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From The Desk of Zelnio: Dermochelys coriacea

So you walk into the pet shop, you’re looking around at all the little animals and you see a cute little turtle in a freshwater terrarium. You think to yourself “wow, that’s really neat, a cute little turtle.” What you might not realize is that a cousin of this pet store turtle holds some most amazing physiological adaptations for non-fish marine vertebrates, can grow more than 2m (6 1/2ft) long, regularly weigh over 500kg (~1000lbs), and dive deeper than most fully-equipped marine organisms can!

Description Dermochelys coriacea, a.k.a. the Leatherback Sea Turtle, was described originally as Testudo coriacea, meaning “leathery turtle” by Vandelli in 1861 (adopted by Linnaeus 5 years later in his Systema Naturae). Dermochelys, meaning something close to “skinned turtle” (as opposed to shelled perhaps?), was bestowed up the Leatherback by Blainville in 1916.  They are the only species in their taxonomic family, the Dermochelyidae. D. coriacea is characterized by its leathery back, absence of scutes (shell plates) and 5 long ridges running from head to tail. The shell is about 4cm thick and composed of an oil-saturated connective tissue. The flippers are proportionally longer than in other sea turtle species, spanning over 2m! That’s basketball player length! The largest specimen on record appears to weigh in at 916kg or 2020lbs (12). Hatchlings can be as small as 50mm (2.4 in.) in length and 50g (just under 2 oz.) and are born mostly black, but covered with tiny white scales that are lost as it grows into an adult.

The Leatherback, armed with torpedo fish. © Michael Patrick O'Neill / oceanwideimages.com

Physiology Heat Conservation: They are able to sustain body temperatures around 25 degrees C when surrounded by water that is 5 degrees C (4). This is helped along by efficient heat conservation system including a low surface area to volume ratio, thick subcutaneous fat layer and countercurrent heat exchangers in the flippers (9). Unusual for a reptile, their resting metabolic rates are 3 times high than in other reptiles, but half as much as mammals when scaled to body size. It is suggested that these turtles can regulate their core temperature by how active they are, more active in the northern latitudes and less active in the tropics (13).

Swimming & Diving: Gravid females top out at around 3m/s (7). Leatherbacks swim more or less continuously at constant speeds and do not take time out to bask in the sunlight (7). They dive in a V pattern and appear to exhibit Diel-Vertical Migration probably following their gelatinous prey as it migrates up and down the water column. Though 95% of all dives less than 200m deep and less than 20 min. long, some dives potentially take a Leatherback to a maximum calculated limit of 1,300m (8). The deepest recorded dive in the literature is 626m and lasted 54 min. though (10). Internesting females have low metabolic rates and are less active, possibly as a mechanism to prevent overheating and to copy with the warmer surface waters of the tropics (15).

Nutrition Leatherbacks appear to exclusively feed on jellies, including medusoid cnidarians, ctenophores and salps (1). Stomach contents from literature include the scyphomedusae of the genera Aurelia, Catostylus, Chrysaora, Cyanea, Pelagia, Rhizostomia, and Stomolophus (1). Hatchlings have also been raised for 6 months on Cassiopea (16) and have been observed  feeding throughout the water column on Aurelia, Ctenophores and unidentified gelatinous eggs (14).  Amazingly this diet supports not only their growth and metabolic functions, but must maintain their endothermy, which is an expensive process. To keep up a core body temperature and also bring the temperature of their food up to their body temperature requires a lot of jellies, which consequently is considered a low quality food item (1)! This is in part helped by oesophagus lined with conical spines and a compartmentalized stomach (5).

Reproduction Leatherback nesting sites range globally between 40°N and 35°S, but the largest concentration of nesting sites is on the Pacific coast of Mexico. Mating happens while females are on migration to their nesting site and DNA evidence of 1000 hatchlings suggests that these turtles are both polyandrous (one mother, many fathers) and polygynous (one father, many mothers) (3). Females come onto the beach at night to lay eggs. Usually, a female returns to the same nesting beach each season. About 70-80 yolked eggs are laid and incubate in the sandy nest for 55-75 days. A significant portion of nests may be lost to beach erosion, some naturally caused but shoreline development and engineering has played a significant role in recent years. Though there are some egg predators, such as fire ants, raccoons and opossum, egg poaching by humans is very common in many parts of the world. Another threat facing nesting sea turtles is climate change. Sex determination in sea turtles is temperature dependent and lower temperatures tend to masculinize a nest. Old nesting sites could potentially be wiped out by masculinization since it is the females the return to their native nesting grounds (6).

Note: Map is updated to today, April 20th, 2009. Click on map to see the latest results from Nat Geo!

Ecology D. coriacea is a highly migratory sea turtle. Juvenile and post-hatchling habitats are not well known, but adults spend the majority of their life in the open ocean. Lab-reared posthatchlings have been shown to use both chemical and visual aids in foraging behavior (2). The chemical cues may be more important a turtles get older and dive deeper. The leatherbacks are often used by barnacles as a habitat as well and can transport barnacle species across oceans!

Biogeography Leatherbacks are found in all oceans, all over the world in latitudes ranging from subarctic to tropical. They can move quite long distances over the course of a year, even crossing whole oceans. One leatherback was tracked moving over 7,000km in only 124 days (11)! There is low genetic diversity between populations globally, compared to other sea turtle species (6). There is evidence of population subdivision along maternal lineages though, supporting the theory of natal homing (versus social facilitation) in leatherbacks. This is somewhat confounded by the low genetic diversity which may be due to ongoing or periodic gene flow, thus suggesting that the natal homing tendency is weak.

Further Reading:

1.    Arai, M. N. 2005. Predation on pelagic coelenterates: a review. Journal of the Marine Biological Association of the UK 85:523-536.

2.    Constantino, M. A., and M. Salmon. 2003. Role of chemical and visual cues in food recognition by leatherback posthatchlings (Dermochelys coriacea L). Zoology 106:173-181.

3.    Crim, J. L., L. D. Spotila, J. R. Spotila, M. O’Connor, R. Reina, C. J. Williams, and F. V. Paladino. 2002. The leatherback turtle, Dermochelys coriacea, exhibits both polyandry and polygyny. Molecular Ecology 11:2097-2106.

4.    Davenport, J. 1998. Sustaining endothermy on a diet of cold jelly: energetics of the leatherback turtle Dermochelys coriacea. British Herpetological Society Bulletin 67:4-8.

5.    Den Hartog, J. C., and M. M. Van Nierop. 1984. A study of the gut contents of six leathery turtles Dermochelys coriacea (Linnaeus) (Reptilia: Testudines: Dermochelyidae) from British waters and from the Netherlands. Zoologische Verhandelingen 209:1-36.

6.    Dutton, P. H., B. W. Bowen, D. W. Owens, A. Barragan, and S. K. Davis. 1999. Global phylogeography of the leatherback turtle (Dermochelys coriacea). Journal of Zoology 248:397-409.

7.    Eckert, S. A. 2002. Swim speed and movement patterns of gravid leatherback sea turtles (Dermochelys coriacea) at St. Croix, US Virgin Islands. Journal of Experimental  Biology 205:3689-3697.

8.    Eckert, S. A., K. L. Eckert, P. Ponganis, and G. L. Kooyman. 1989. Diving and foraging behaviour of leatherback sea turtles Dermochelys coriacea. Canadian Journal of Zoology 67:2834-2840.

9.    Greer, A. E., J. D. Lazell, and R. M. Wright. 1973. Anatomical evidence for a counter-current heat exchanger in the leatherback turtle (Dermochelys coriacea). Nature 244:181.

10.    Hays, G. C., J. D. R. Houghton, C. Isaacs, R. S. King, C. Lloyd, and P. Lovell. 2004. First records of oceanic dive profiles for leatherback turtles, Dermochelys coriacea, indicate behavioural plasticity associated with long-distance migration. Animal Behaviour 67:733-743.

11.    Hughes, G. R., P. Luschi, R. Mencacci, and F. Papi. 1998. The 7,000-km oceanic journey of a leatherback turtle tracked by satellite. Journal of Experimental  Marine Biology & Ecology 229    :209-217.

12.    Morgan, P. J. 1989. Presented at the Ninth Annual Conference of Sea Turtle Conservation and Biology, Vero Beach, FL.

13.    Paladino, F. V., M. P. O’Connor, and J. R. Spotila. 1990. Metabolism of leatherback turtles, gigantothermy, and thermoregulation of dinosaurs. Nature 344:858-860.

14.    Salmon, M., T. T. Jones, and K. W. Horch. 2004. Ontogeny of diving and feeding behavior in juvenile seaturtles: leatherback seaturtles (Dermochelys coriacea L) and green seaturtles (Chelonia mydas L) in the Florida Current. Journal of Herpetology 38:36-43.

15.    Wallace, B. P., C. L. Williams, F. V. Paladino, S. J. Morreale, R. T. Lindstrom, and J. R. Spotila. 2005. Bioenergetics and diving activity of internesting leatherback turtles Dermochelys coriacea at Parque Nacional Marino Las Baulas, Costa Rica. Journal of Experimental  Biology 208:3873-3884.

16.    Witham, R., and C. R. Futch. 1977. Early growth and oceanic survival of pen-reared sea turtles. Herpetologica 33:404-409.

From the world famous “Dance Your Dissertation” contest, now on YouTube with a methods section. This video depicts a dissertation entitled “The invention and adoption of conservation technology to successfully reduce the bycatch of protected marine species” by Lekelia, using a mix of modern dance and watusi styles in the remarkable Sea Turtle Conservation Dance.

Click here to learn more.