Animal Diversity Web

Ge­o­graphic Range

Leatherbacks are pri­mar­ily pelagic an­i­mals. They travel great dis­tances from their nest­ing beaches to their feed­ing grounds. Al­though leatherbacks are most often found in trop­i­cal wa­ters, they are dis­trib­uted around the globe in tem­per­ate oceans, and even on edges of sub­arc­tic water. The leatherback sea tur­tle trav­els fur­ther north than any other sea tur­tle. They live in North­ern At­lantic wa­ters as far north as New­found­land, Nova Sco­tia, and Labrador. They also in­habit South At­lantic Wa­ters, as far south as Ar­gentina and South Africa. This tur­tle in­hab­its wa­ters as far east as Britain and Nor­way.

Dur­ing the nest­ing sea­son they are dis­cov­ered along the coasts of French Guiana, Suri­name, Guyana, Trinidad, Gabon, West Africa, Par­que Marino Las Baulas in Gua­nacaste, Costa Rica, Papua New Guinea, An­daman and Nico­bar Is­lands, Thai­land, in the U.S. on St. Croix, U.S. Vir­gin Is­lands, and in Puerto Rico and Florida. The largest nest­ing colony is in Africa, along the coast of French Guiana. More than 7,000 fe­males laid as many as 50,000 eggs there in 1988 and again in 1992. There is one nest­ing record in Cape Look­out, North Car­olina. (Eck­ert, 2006; Martof, et al., 1980; Spotila, 2004)

• Biogeographic Regions
• oceanic islands
  • native
• indian ocean
  • native
• atlantic ocean
  • native
• pacific ocean
  • native

Habi­tat

Leatherback sea tur­tles live in many dif­fer­ent oceans through­out the world. They are widely known as pelagic an­i­mals but are seen in coastal wa­ters when search­ing for food. They live in trop­i­cal, tem­per­ate and even some sub­arc­tic oceans. They have been dis­cov­ered in wa­ters as deep as 1230 m, well below the photic zone.

Leatherbacks lay their eggs in the sand of trop­i­cal beaches. It is the only time they emerge onto land, and only the fe­males do so. (Eck­ert, 2006; Spotila, 2004)

• Habitat Regions
• temperate
• tropical
• saltwater or marine

• Aquatic Biomes
• pelagic
• coastal

• Other Habitat Features
• intertidal or littoral

• Range depth

  1230 (high) m

  4035.43 (high) ft

Phys­i­cal De­scrip­tion

The leatherback sea tur­tle is the largest of liv­ing tur­tles. It may reach a length of ca. 2.13 m. Adults may have a span of ca. 2.7 m from the tip of one front flip­per to the tip of the other. They have a sec­ondary palate, formed by vomer and pala­tine bones. The leatherback has no vis­i­ble shell. The shell is pre­sent but it con­sists of bones that are buried into its dark brown or black skin. It has seven pro­nounced ridges in its back and five on the un­der­side. Leatherback hatch­lings look mostly black when look­ing down on them, and their flip­pers are mar­gined in white. Rows of white scales give hatch­ling leatherbacks the white strip­ing that runs down the length of their backs.

These tur­tles feed in wa­ters that are far colder than other sea tur­tles can tol­er­ate. They have a net­work of blood ves­sels that work as a counter-cur­rent heat ex­changer, a thick in­su­lat­ing layer of oils and fats in their skin, and are able to main­tain body tem­per­a­tures much higher than their sur­round­ings. (Spotila, 2004)

• Other Physical Features
• ectothermic
• heterothermic
• bilateral symmetry

• Sexual Dimorphism
• female larger

• Range mass

  250 to 900 kg

  550.66 to 1982.38 lb

• Range length

  145 to 160 cm

  57.09 to 62.99 in

De­vel­op­ment

Hatch­ing suc­cess of clutches is about 50% in an undis­turbed nest. Many nests are de­stroyed by many dif­fer­ent preda­tors. Nest tem­per­a­ture de­ter­mines the hatch­lings' sex. At 29.5 de­grees Cel­sius hatch­lings are equally likely to be male or fe­male, hatch­lings in­cu­bated at 28.75°C or less will be male, above 29.75°C they'll be fe­male. Hatch­ling tur­tles weigh 35-50 grams, and grow very fast. Leatherbacks may be the fastest grow­ing rep­tile in the world, reach­ing adult size in 7 - 13 years. (Spotila, 2004)

• Development - Life Cycle
• temperature sex determination

Re­pro­duc­tion

The male leatherback tur­tles will mi­grate just off­shore a com­mon nest­ing beach gen­er­ally be­fore nest­ing sea­son be­gins. There they will try and mate with as many fe­males as pos­si­ble. Also, stud­ies have shown that the males will re­turn to the same nest­ing beach if they were suc­cess­ful in the pre­vi­ous sea­son. (Eck­ert, et al., 2005)

• Mating System
• polygynandrous (promiscuous)

Leatherback sea tur­tles mate in the water, just off­shore from the fe­males' de­sired nest­ing beach. The fe­male then swims ashore at night to nest and will pro­duce a clutch of usu­ally 50 - 170 eggs. How­ever, a large per­cent­age of those eggs are yolk­less and will not de­velop fur­ther. The fe­male will lay her eggs and then cover the nest with sand to dis­cour­age pre­da­tion and mod­er­ate the tem­per­a­ture and hu­mid­ity around the eggs. After the fe­male has com­pleted this process she will re­turns to the ocean. Male leatherback sea tur­tles never swim to shore and have no part in the nest­ing process. (Bar­bour and Ernst, 1972; Beacham, et al., 2000; Eck­ert, et al., 2005; Zug and Parham, 1996)

• Key Reproductive Features
• semelparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
• oviparous

• Breeding interval

  Leatherback Sea Turtles will lay about 5 to 7 nests per year, renesting every 9 to 10 days. Also, they will return to the same nesting location every 2 to 3 years.

• Breeding season

  They generally reproduce between the months of April and November.

• Range number of offspring

  50 to 70

• Average number of offspring

  105

  AnAge

• Range gestation period

  55 to 75 days

• Average time to independence

  immediate (no parental investment past egg-laying) minutes

• Range age at sexual or reproductive maturity (female)

  5 to 21 years

The only parental in­vest­ment that oc­curs with leatherback sea tur­tles is when the fe­male lays eggs on the shore and cov­ers her nest after lay­ing the eggs. No sub­se­quent parental care oc­curs. (Bar­bour and Ernst, 1972)

• Parental Investment
• pre-fertilization
  • provisioning
  • protecting
    • female

Lifes­pan/Longevity

We have no in­for­ma­tion on the lifes­pan of Der­mochelys co­ri­acea. (Bar­bour and Ernst, 1972; Pope, 1939)

• Average lifespan
  Status: captivity

  30 years

  AnAge

Be­hav­ior

Leatherbacks are mostly soli­tary. They mi­grate great dis­tances be­tween nest­ing and feed­ing grounds. They seem to lo­cate lo­ca­tions that have high con­cen­tra­tions of jel­ly­fish, and feed near the sur­face or dive to find the high­est con­cen­tra­tions of prey. (Alder­ton, 1988; Carr, 1952; Pope, 1939)

• Key Behaviors
• natatorial
• motile
• migratory
• solitary

Food Habits

Leatherback tur­tles are car­ni­vores that feed in the open ocean. Their main prey are gelati­nous in­ver­te­brates, mainly jel­ly­fish and salps. They are known to eat other kinds of food though, in­clud­ing small crus­taceans and fish (pos­si­bly sym­biotes with jel­lies), cephalopods, sea urchins, and snails.

Leatherbacks do not have the pow­er­ful mus­cles and hard crush­ing jaw ap­pa­ra­tus that some other sea tur­tles have for eat hard-shelled prey. In­stead they have sharp-edged jaws for bit­ing soft-bod­ied prey. The esoph­a­gus in this species is lined with short spines that point down­stream, pre­vent­ing jel­lies from es­cap­ing once swal­lowed. (Caut, et al., 2006; Houghton, et al., 2006)

• Primary Diet
• carnivore
  • eats other marine invertebrates

• Animal Foods
• fish
• mollusks
• aquatic or marine worms
• aquatic crustaceans
• echinoderms
• cnidarians
• zooplankton

Pre­da­tion

In mod­ern times, hu­mans have be­come the pri­mary preda­tor of this species, gath­er­ing eggs and killing adults.

Leatherback tur­tles eggs are con­sumed by a large va­ri­ety of preda­tors, in­clud­ing ghost crabs (Ocy­pode), mon­i­tor lizards (Varanus), wad­ing birds such as turn­stones (Are­naria), knots (Calidris), and plovers Plu­vi­alis). Many mam­mals ex­ca­vate nests as well, in­clud­ing rac­coons (Pro­cyon lotor) and coatis (Nasua), dogs (Canis), genets (Genetta), mon­gooses (Her­pesti­dae) and pigs (Suidae). Most of these same preda­tors will take hatch­lings as the lit­tle tur­tles race for the sea, as will rap­tors (Fal­coni­formes), gulls (Larus), and frigate birds (Fre­gati­dae). In the ocean, small leatherbacks are at­tacked by cephalopods, re­quiem sharks (Car­charhinidae) and other large fish. Adult leatherbacks are large and pow­er­ful enough to have few preda­tors, but jaguars (Pan­thera onca) and other large preda­tors may at­tack nest­ing fe­males, and killer whales (Or­ci­nus orca) and large sharks may at­tack them at sea.

Nest­ing fe­males pack the sand over their clutch of eggs, per­haps to ob­scure the scent of the eggs and make them harder for small preda­tors to dig up. Hatch­lings wait until night­fall to emerge and head for the water, to avoid preda­tors. Through­out their lives leatherbacks are counter-shaded, dark on the dor­sal sur­face and light un­der­neath, to bet­ter blend with back­ground light (though the dark dor­sal sur­face is prob­a­bly also bet­ter for bask­ing).

Al­though they don't have the bony shell of most tur­tles, they do have a thick layer of con­nec­tive tis­sue over bony plates cov­er­ing much most of their body. Leatherbacks are strong and fast swim­mers, and adults may de­fend them­selves ag­gres­sively. One adult (c. 1.5 m long) was seen chas­ing a shark that had ap­par­ently at­tacked it, and once the shark fled, the tur­tle at­tacked the boat that the ob­servers were in. (Caut, et al., 2006; Chi­ang, 2003; Ernst, et al., 1994)

• Known Predators

  • ghost crabs (Ocypode)
  • monitor lizards (Varanus)
  • turnstones (Arenaria)
  • knots (Calidris)
  • plovers Pluvialis)
  • raccoons (Procyon lotor)
  • coatis (Nasua)
  • genets (Genetta)
  • dogs (Canis lupus familiaris)
  • mongooses (Herpestidae)
  • pigs (Sus)
  • cephalopods (Cephalopoda)
  • requiem sharks (Carcharhinidae)
  • killer whales (Orcinus orca)
  • frigate birds (Fregatidae)
  • vultures and hawks (Falconiformes)

Ecosys­tem Roles

Leatherback sea tur­tles are preda­tors that eat mainly jel­ly­fish and other soft-bod­ied ma­rine an­i­mals. Their af­fect on prey pop­u­la­tion den­si­ties is un­known, but might have been sub­stan­tial be­fore their pop­u­la­tions were re­duced by har­vest­ing.

Leatherback eggs and hatch­lings may be a sig­nif­i­cant food source for egg preda­tor pop­u­la­tions near their nest­ing beaches.

Leatherbacks are the host of Con­cho­derma vir­ga­tum, a com­men­sal species of bar­na­cle. (Eck­ert and Eck­ert, 1987; Ernst, et al., 1994; Spotila, 2004)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Al­though the flesh of adult leatherbacks can some­times be toxic, adults and eggs are used for food in some lo­ca­tions, and in a few places the oil from the bod­ies of adults is ex­tracted for med­i­c­i­nal use and as a wa­ter­proof­ing agent.

Leatherbacks eat jel­ly­fish that are pests for swim­mers and fish­er­men, es­pe­cially for ma­rine fish-farm­ing. Con­sump­tion es­ti­mates vary, one study es­ti­mated that adult leatherbacks prob­a­bly eat about 1000 kg of jel­ly­fish per year, an ear­lier study es­ti­mated 2900-3650 kg/yr. (Spotila, 2004; Ernst, et al., 1994; Spotila, 2004; United States Fish and Wildlife Ser­vice, 2007)

• Positive Impacts
• food
• body parts are source of valuable material

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

This species does not harm hu­mans or cause sig­nif­i­cant costs. It's flesh is some­times toxic to hu­mans and other an­i­mals, per­haps due to tox­ins in­gested as part of its diet of jel­ly­fish.

• Negative Impacts
• injures humans
  • poisonous

Con­ser­va­tion Sta­tus

This species is be­lieved to be in se­ri­ous de­cline. Pop­u­la­tions of nest­ing fe­males in the Pa­cific have de­clined as much as 70-80% in the last decade, and the sta­tus of the At­lantic pop­u­la­tion is un­clear. Be­cause fe­males may nest on more than one beach each year, ac­cu­rate counts are more dif­fi­cult than for some other tur­tle species. The species is rated "Crit­i­cally En­dan­gered" by the IUCN, and "En­dan­gered" by the U.S. Fish & Wildlife Ser­vice. It has been listed in Ap­pen­dix I of the CITES, mak­ing any in­ter­na­tional trade il­le­gal.

The pri­mary threat to the species is com­mer­cial fish­ing: tur­tles ac­ci­den­tally trapped and drowned in nets and trawls, or hooked or tan­gled by long­lines and trap lines. Har­vest­ing of eggs is a sig­nif­i­cant prob­lem as well. Also, leatherbacks ap­par­ently some­times eat plas­tic de­bris they find in the water, prob­a­bly mis­tak­ing it for jel­ly­fish. This plas­tic de­bris is in­di­gestible, and an in­creas­ing num­ber of tur­tles are found dead with blocked di­ges­tive tracts.

Na­ture re­serves have been es­tab­lished in the coastal areas where the tur­tles come to breed to pre­vent peo­ple from steal­ing the eggs. In some areas, sci­en­tists have taken the eggs into cap­tive breed­ing pro­grams to try to in­crease the pop­u­la­tion of the area. Some gov­ern­ments re­quire use of tur­tle-ex­clu­sion de­vices on fish­ing gear, but this is not a wide­spread prac­tice. (Ernst, et al., 1994; Na­tional Oceanic and At­mos­pheric Ad­min­is­tra­tion, Of­fice of Pro­tected Re­sources, April 13, 2001)

In July of 2004, the “Ma­rine Tur­tle Con­ser­va­tion Act” was signed into law in the United States. The pur­pose of this bill was to aid in the con­ser­va­tion of ma­rine tur­tles, as well as to as­sist for­eign coun­tries in pre­serv­ing their nest­ing habi­tats. To sup­port this bill there are hopes of cre­at­ing a “Multi­na­tional Species Con­ser­va­tion Fund” to sup­port con­ser­va­tion of im­per­iled ma­rine tur­tles, in­clud­ing the leatherback. (Evans, 2004)

• IUCN Red List

  Critically Endangered
  More information

• IUCN Red List

  Critically Endangered
  More information

• US Federal List

  Endangered

• CITES

  Appendix I

Con­trib­u­tors

Adam Farmer (au­thor), Rad­ford Uni­ver­sity, An­na­marie Roszko (au­thor), Rad­ford Uni­ver­sity, Scott Flore (au­thor), Rad­ford Uni­ver­sity, Kevin Hat­ton (au­thor), Rad­ford Uni­ver­sity, Veron­ica Com­bos (au­thor), Rad­ford Uni­ver­sity, An­drea Hel­ton (au­thor), Rad­ford Uni­ver­sity, Karen Pow­ers (ed­i­tor, in­struc­tor), Rad­ford Uni­ver­sity.

Fer­min Fontanes (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

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Eck­ert, S., M. James, R. Myers. 2005. Mi­gra­tory and re­pro­duc­tive move­ments of male leatherback tur­tles. Ma­rine Bi­ol­ogy, 147(4): 845.

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