Early Cretaceous-Holocene, 110–0 Ma
|An olive ridley sea turtle, a species of the sea turtle superfamily|
|Order:||Testudines salchi turtles|
Chelonii - Oppel 1811
Sea turtles (superfamily Chelonioidea), sometimes called marine turtles, are reptiles of the order Testudines. The seven extant species of sea turtles are: the green, loggerhead, Kemp's ridley, olive ridley, hawksbill, flatback, and leatherback.
- 1 Taxonomy and evolution
- 2 Distribution and habitat
- 3 Life cycle
- 4 Physiology
- 5 Ecology
- 5.1 Diet
- 5.2 Relationship with humans
- 5.3 Importance to ecosystems
- 5.4 Conservation status and threats
- 5.5 Symbiosis with barnacles
- 6 See also
- 7 Additional reading
- 8 References
- 9 External links
Taxonomy and evolution
Sea turtles, along with other turtles and tortoises, are part of the order Testudines. All species except the leatherback are in the family Cheloniidae. The leatherback is the only extant member of the family Dermochelyidae.
In general, sea turtles have a more fusiform body plan than their terrestrial or freshwater counterparts. The reduced volume of a fusiform body means sea turtles can not retract their head, legs, and arms into their shells, like other turtles can.
The species are primarily distinguished by their anatomy: for instance, the prefrontal scales on the head, the number of and shape of scutes on the carapace, and the type of inframarginal scutes on the plastron.
The leatherback is the only sea turtle that does not have a hard shell. Instead, it bears a mosaic of bony plates beneath its leathery skin. It is the largest sea turtle, measuring 6 to 9 feet (1.8 to 2.7 m) in length at maturity, and 3 to 5 feet (0.91 to 1.52 m) in width, weighing up to 1,500 pounds (680 kg). Other species are smaller, being mostly 2 to 4 feet (0.61 to 1.22 m) and proportionally narrower.
The origin of sea turtles goes back to the Late Jurassic (150 million years ago) with genera such as Plesiochelys, from Europe. In Africa, the first marine turtle is Angolachelys, from the Turonian of Angola. However, neither of these are related to extant sea turtles; the oldest representative of the lineage leading to these was Desmatochelys padillai , from the Early Cretaceous.
Sea turtles constitute a single radiation that became distinct from all other turtles at least 110 million years ago.
- Family Cheloniidae
- Family Dermochelyidae
- Dermochelys coriacea, leatherback sea turtle
Distribution and habitat
Sea turtles can be found in all oceans except for the polar regions. They mostly can be found in coral reefs. Some species travel between oceans. The flatback sea turtle is found solely on the northern coast of Australia. The Kemp's ridley sea turtle is found solely in the Gulf of Mexico and along the East Coast of the United States.
Sea turtles are generally found in the waters over continental shelves. During the first three to five years of life, sea turtles spend most of their time in the pelagic zone floating in seaweed mats. Green sea turtles in particular are often found in Sargassum mats, in which they find shelter and food. Once the sea turtle has reached adulthood it moves closer to the shore. Females will come ashore to lay their eggs on sandy beaches during the nesting season.
The habitat of a sea turtle has a significant influence on its morphology. Sea turtles are able to grow so large because of the immense size of their habitat: the ocean. The reason that sea turtles are much bigger than land tortoises and freshwater turtles is directly correlated with the vastness of the ocean, and the fact that they travel such far distances. Having more room to live enables more room for growth.
||This article may contain too much repetition or redundant language. (July 2015)|
It takes decades for sea turtles to reach sexual maturity. Mature turtles may migrate thousands of miles to reach breeding sites. After mating at sea, adult female sea turtles return to land to lay their eggs. Different species of sea turtles exhibit various levels of philopatry. In the extreme case, females return to the beach where they hatched. This can take place every two to four years in maturity.
The mature nesting female hauls herself onto the beach, nearly always at night, and finds suitable sand in which to create a nest. Using her hind flippers, she digs a circular hole 40 to 50 centimetres (16 to 20 in) deep. After the hole is dug, the female then starts filling the nest with her clutch of soft-shelled eggs. Depending on the species, a typical clutch may contain 50-350 eggs. After laying, she re-fills the nest with sand, re-sculpting and smoothing the surface, and then camouflaging the nest with vegetation until it is relatively undetectable visually. The whole process takes thirty to sixty minutes. She then returns to the ocean, leaving the eggs untended.
Females may lay 1–8 clutches in a single season. Female sea turtles alternate between mating in the water and laying their eggs on land. Most sea turtle species nest individually. But ridley sea turtles come ashore en masse, known as an arribada (arrival). With the Kemp's ridley sea turtles this occurs during the day.
Sea turtles have temperature-dependent sex determination, meaning the developing turtle's gender depends on the temperature it is exposed to. Warmer temperatures produce female hatchlings, while cooler temperatures produce male hatchlings. The eggs will incubate for 50–60 days. The eggs in one nest hatch together over a short period of time. The baby turtles break free of the egg shell, dig through the sand, and crawl into the sea. Most species of sea turtles hatch at night. However, the Kemp's ridley commonly hatches during the day. Turtle nests that hatch during the day are more vulnerable to predators, and may encounter more human activity on beach.
Larger hatchlings have a higher probability of survival than smaller individuals, which can be explained by the fact that larger offspring are faster and thus less exposed to predation. Predators can only functionally intake so much; larger individuals are not targeted as often. A study conducted on this topic shows that body size is positively correlated with speed, so larger turtles are exposed to predators for a shorter amount of time. The fact that there is size dependent predation on chelonians has led to the evolutionary development of large body sizes.
In 1987, Carr discovered that the young of green and loggerhead seaturtles spent a great deal of their pelagic lives in floating sargassum mats. Within these mats, they found ample shelter and food. In the absence of sargassum, sea turtle young feed in the vicinity of upwelling "fronts". In 2007, Reich determined that green sea turtle hatchlings spend the first three to five years of their lives in pelagic waters. In the open ocean, pre-juveniles of this particular species were found to feed on zooplankton and smaller nekton before they are recruited into inshore seagrass meadows as obligate herbivores.
Sea turtles maintain an internal environment that is hypotonic to the ocean. To maintain hypotonicity they must excrete excess salt ions. Like other marine reptiles, sea turtles rely on a specialized gland to rid the body of excess salt ions, because reptilian kidneys can not produce urine with a higher ion concentration than sea water. All species of sea turtles have a lachrymal gland in the orbital cavity, capable of producing tears with a higher salt concentration than sea water.
Leatherbacks face an increased osmotic challenge compared to other species of sea turtle, since their primary prey are jellyfish and other gelatinous plankton, whose fluids have the same concentration of salts as sea water. The much larger lachrymal gland found in leatherbacks may have evolved to cope with the higher intake of salts from their prey. A constant output of concentrated salty tears may be required to balance the input of salts from regular feeding, even considering leatherback tears can have a salt ion concentration almost twice that of other species of marine turtle.
Hatchlings depend on drinking sea water immediately upon entering the ocean to replenish water lost during the hatching process. Salt gland functioning begins quickly after hatching, so that the young turtles can establish ion and water balance soon after entering the ocean. Survival and physiological performance hinge on immediate and efficient hydration following emergence from the nest.
Most sea turtles (those in family Cheloniidae) are poikilotherms. However the leatherback (family Dermochelyidae) are endotherms because they can maintain a body temperature 8 °C warmer than the ambient water.
Green sea turtles in the relatively cooler Pacific are known haul themselves out of the water on remote islands to bask in the sun. This behavior has only been observed in a few locations including the Galapagos, Hawaii, Europa Island, and parts of Australia.
Sea turtles are air breathing reptiles that have lungs, so they regularly surface to breathe. Sea turtles spend a majority of their time underwater, so they must be able to hold their breath for long periods. Dive duration largely depends on activity. A foraging turtle may typically spend 5–40 min under water while a sleeping sea turtle can remain under water for 4–7 hours. Remarkably, sea turtle respiration remains aerobic for the vast majority of voluntary dive time. When a sea turtle is forcibly submerged (e.g. entangled in a trawl net) its diving endurance is substantially reduced, so it is more susceptible to drowning.
When surfacing to breathe, a sea turtle can quickly refill its lungs with a single explosive exhalation and rapid inhalation. Their large lungs permit rapid exchange of oxygen and avoid trapping gases during deep dives.
The loggerhead, Kemp's ridley, olive ridley, hawksbill, flatback, and leatherback sea turtles are omnivorous for their entire life. Omnivorous turtles may eat a wide variety of plant and animal life including, decapods, seagrasses, seaweed, sponges, mollusks, cnidarians, echinoderms, worms and fish. However some species specialize on certain prey.
The diet of green turtles changes with age. Juveniles are omnivorous, but as they mature they become exclusively herbivorous. This diet shift has an effect on the green turtle's morphology. Green sea turtles have a serrated jaw that is used to eat sea grass and algae.
Hawksbills principally eat sponges, which constitute 70–95% of their diets in the Caribbean.
Relationship with humans
Marine sea turtles are caught worldwide, although it is illegal to hunt most species in many countries. A great deal of intentional marine sea turtle harvests worldwide are for food. Many parts of the world have long considered sea turtles to be fine dining. Ancient Chinese texts dating to the fifth century B.C.E. describe sea turtles as exotic delicacies. Many coastal communities around the world depend on sea turtles as a source of protein, often harvesting several sea turtles at once and keeping them alive on their backs until needed. Coastal peoples gather sea turtle eggs for consumption.
To a much lesser extent, specific species of marine sea turtles are targeted not for their flesh, but for their shells. Tortoiseshell, a traditional decorative ornamental material used in Japan and China, comes from the carapace scutes of the hawksbill sea turtle. Ancient Greeks and ancient Romans processed sea turtle scutes (primarily from the hawksbill) for various articles and ornaments used by their elites, such as combs and brushes. The skin of the flippers is prized for use as shoes and assorted leather goods.
Leatherback sea turtles enjoy immunity from the sting of the deadly box jellyfish and regularly eat them, helping keep tropical beaches safe for humans.
Beach towns, such as Tortuguero, Costa Rica, have transitioned from a tourism industry that made profits from selling sea turtle meat and shells to an ecotourism-based economy. Tortuguero is considered to be the founding location of sea turtle conservation. In the 1960s the cultural demand for sea turtle meat, shells, and eggs was quickly killing the once abundant sea turtle populations that nested on the beach. The Caribbean Conservation Corporation began working with villagers to promote ecotourism as a permanent substitute to sea turtle hunting. Sea turtle nesting grounds became sustainable. Since the creation of a sea turtle, ecotourism-based economy, Tortugero annually houses thousands of tourists who visit the protected 22-mile beach that hosts sea turtle walks and nesting grounds.
Importance to ecosystems
Sea turtles play key roles in two habitat types: oceans and beaches/dunes.
In the oceans, sea turtles, especially green sea turtles, are one of very few creatures (manatees are another) that eat sea grass. Sea grass needs to be constantly cut short to help it grow across the sea floor. Sea turtle grazing helps maintain the health of the sea grass beds. Sea grass beds provide breeding and developmental grounds for numerous marine animals. Without sea grass beds, many marine species humans harvest would be lost, as would the lower levels of the food chain. The reactions could result in many more marine species eventually becoming endangered or extinct.
Sea turtles use beaches and the lower dunes to nest and lay their eggs. Beaches and dunes are a fragile habitat that depend on vegetation to protect against erosion. Eggs, hatched or unhatched, and hatchlings that fail to make it into the ocean are nutrient sources for dune vegetation. Along a 20-mile stretch of beach on the east coast of Florida sea turtles lay over 150,000 lbs of eggs in the sand. Dune vegetation is able to grow and become stronger with the nutrients from sea turtle nests. Stronger vegetation and root systems help to hold the sand in the dunes and help protect the beach from erosion.
Conservation status and threats
The IUCN Red List classifies three species of sea turtle as either "Endangered" or "Critically Endangered". An additional three species are classified as "Vulnerable". The flatback is considered as "Data Deficient", meaning that its conservation status is unclear due to lack of data. All species of sea turtle are listed in CITESAppendix I, restricting international trade of sea turtles and sea turtle products.
Additionally, all populations of sea turtles that occur in United States waters are listed as threatened or endangered by the US Endangered Species Act (ESA). The US listing status of the loggerhead is under review as of 2012.
|IUCN Redlist||United States ESA*|
|Green||Endangered||Endangered: populations in Florida and Pacific coast of Mexico populations
Threatened: all other populations
|Loggerhead||Vulnerable||Endangered: NE Atlantic, Mediterranean, N Indian, N Pacific, S Pacific populations
Threatened: NW Atlantic, S Atlantic, SE Indo-Pacific, SW Indian populations
|Kemp's ridley||Critically Endangered||Endangered: all populations|
|Olive ridley||Vulnerable||Endangered: Pacific Coast of Mexico population
Threatened: all other populations
|Hawksbill||Critically Endangered||Endangered: all populations|
|Leatherback||Vulnerable||Endangered: all populations|
*The ESA manages sea turtles by population not by species.
In the Caribbean, researchers are having some success in assisting a comeback. In September 2007, Corpus Christi, Texas, wildlife officials found 128 Kemp's ridley sea turtle nests on Texas beaches, a record number, including 81 on North Padre Island (Padre Island National Seashore) and four on Mustang Island. Wildlife officials released 10,594 Kemp's ridleys hatchlings along the Texas coast this year.
The Philippines has had several initiatives dealing with the issue of sea turtle conservation. In 2007, the province of Batangas declared the catching and eating of sea turtles (locally referred to as Pawikans) illegal. However, the law seems to have had little effect as sea turtle eggs are still in demand in Batangan markets. In September 2007, several Chinese poachers were apprehended off the Turtle Islands in the country's southernmost province of Tawi-Tawi. The poachers had collected more than a hundred sea turtles, along with 10,000 sea turtle eggs.
Evaluating the progress of conservation programs is difficult, because many sea turtle populations have not been assessed adequately. Most information on sea turtle populations comes from counting nests on beaches, but this doesn’t provide an accurate picture of the whole sea turtle population. A 2010 United States National Research Council report concluded that more detailed information on sea turtles’ life cycles, such as birth rates and mortality, is needed.
Nest relocation may not be a useful conservation technique for sea turtles. In one study on the freshwater Arrau turtle (Podocnemis expansa) researchers examined the effects of nest relocation. They discovered that clutches of this freshwater turtle that were transplanted to a new location had higher mortality rates and more morphological abnormalities compared to non transplanted clutches. The results clearly demonstrate that humans should not manipulate or relocate clutches of that turtle, and impart strong evidence of the detrimental effects that human activity can cause.
Predators and disease
Most sea turtle mortality happens early in life. Sea turtles usually lay around one hundred eggs at a time, on average only one of the eggs from the nest will survive to adulthood. Nests may be raided by raccoons and foxes. Within minutes of hatching, hatchlings may be eaten by raccoons, foxes, seabirds, as they make their initial run for the ocean. Once in the water they are susceptible to seabirds, large fish and even other turtles.
Adult sea turtles have few predators. Large aquatic carnivores such as sharks and crocodiles are the biggest threat. Reports of terrestrial predators attacking nesting females are not uncommon. Jaguars have been reported to smash into the turtle's shell with its paw, and scoop out the flesh.
Fibropapillomatosis disease causes tumors in sea turtles.
While many of the things that endanger these hatchlings are natural, such as predators including sharks, raccoons, foxes, and seagulls, many new threats to the sea turtle species have recently arrived and increased with the ever-growing presence of humans.
One of the most significant threats now comes from bycatch due to imprecise fishing methods. Long-lining has been identified as a major cause of accidental sea turtle death. There is also black-market demand for tortoiseshell for both decoration and supposed health benefits.
Sea turtles must surface to breathe. Caught in a fisherman's net, they are unable to surface and thus drown. In early 2007, almost a thousand sea turtles were killed inadvertently in the Bay of Bengal over the course of a few months after netting.
However, some relatively inexpensive changes to fishing techniques, such as slightly larger hooks and traps from which sea turtles can escape, can dramatically cut the mortality rate. Turtle Excluder Devices (TEDs) have reduced sea turtle bycatch in shrimp nets by 97 percent.
Beach development is another area which threatens sea turtles. Since many sea turtles return to the same beach each time to nest, development can disrupt the cycle. There has been a movement to protect these areas, in some cases by special police. In some areas, such as the east coast of Florida, conservationists dig up sea turtle eggs and relocate them to fenced nurseries to protect them from beach traffic.
Since hatchlings find their way to the ocean by crawling towards the brightest horizon, they can become disoriented on developed stretches of coastline. Lighting restrictions can prevent lights from shining on the beach and confusing hatchlings. Sea turtle-safe lighting uses red or amber LED light, invisible to sea turtles, in place of white light.
Another major threat to sea turtles is black-market trade in eggs and meat. This is a problem throughout the world, but especially a concern in China, the Philippines, India, Indonesia and the coastal nations of Latin America. Estimates reach as high as 35,000 sea turtles killed a year in Mexico and the same number in Nicaragua. Conservationists in Mexico and the United States have launched "Don't Eat Sea Turtle" campaigns in order to reduce this trade in sea turtle products. These campaigns have involved figures such as Dorismar, Los Tigres del Norte and Maná. Sea turtles are often consumed during the Catholic season of Lent, even though they are reptiles, not fish. Consequently, conservation organizations have written letters to the Pope asking that he declare sea turtles meat.
Climate change may also cause a threat to sea turtles. Since sand temperature at nesting beaches defines the sex of a sea turtle while developing in the egg, there is concern that rising temperatures may produce too many females. However, more research is needed to understand how climate change might affect sea turtle gender distribution and what other possible threats it may pose.
Sea turtles are very vulnerable to oil pollution, both because of their tendency to linger on the water's surface, and because oil can affect them at every stage of their life cycle. Oil can poison the sea turtles upon entering their digestive system.
Injured sea turtles are rescued and rehabilitated (and, if possible, released back to the ocean) by professional organizations, such as:
- Sea Turtles 911 in Hainan, China
- Loggerhead Marinelife Center in Juno Beach, Florida
- The Turtle Hospital in Marathon, Florida
- Mote Marine Laboratory in Sarasota, Florida
- Marine Mammal Center in Northern California
- Clearwater Marine Aquarium in Clearwater, Florida
- The Marine Mammal Center and The Florida Aquarium in Tampa, Florida
- Sea Turtle Inc. in South Padre Island, Texas
- Georgia Sea Turtle Center, Jekyll Island, Georgia.
Symbiosis with barnacles
Sea Turtles are believed to have a commensal relationship with some barnacles, in which the barnacles benefit from growing on turtles without harming them. Barnacles are small, hard shelled crustaceans found attached to multiple different substrates below or just above the ocean. The adult barnacle is a sessile organism, however in its larval stage it is planktonic and can move about the water column. The larval stage chooses where to settle and ultimately the habitat for its full adult life, which is typically between 5 and 10 years. A favorite settlement for barnacle larvae is the shell or skin around the neck of sea turtles. The larvae glue themselves to the chosen spot, a thin layer of flesh is wrapped around them and a shell is secreted. Many species of barnacles can settle on any substrate, however some species of barnacles have an obligatory commensal relationship with specific animals, which makes finding a suitable location harder. Around 29 species of "turtle barnacles" have been recorded. However it is not solely on sea turtles that barnacles can be found; other organisms also serve as barnacle’s settlements. These organisms include mollusks, whales, decapod crustaceans, manatees and several other groups related to these species.
Sea turtle shells are an ideal habitat for adult barnacles for three reasons. Turtles tend to live long lives, around 50 years, so barnacles do not have to worry about host death. Secondly, barnacles are suspension feeders. Sea turtles spend most of their lives swimming and following ocean currents and as water runs along the back of the turtle’s shell it passes over the barnacles, providing an almost constant water flow and influx of food particles. Lastly, the long distances and inter ocean travel these sea turtles swim throughout their lifetime, offers the perfect mechanism for dispersal of barnacle larvae. Allowing the barnacle species to distribute themselves throughout global waters is a high fitness advantage of this commensalism.
This relationship however is not truly commensal. While the barnacles are not directly parasitic to their hosts, they have negative effects to the turtles on which they choose to reside. The barnacles add extra weight and drag to the sea turtle, increasing the energy it needs for swimming and affecting its ability to capture prey, with the effect increasing with the quantity of barnacles affixed to its back.
- Cultural depictions of turtles
- Kélonia -sea turtle oberservatory in Réunion
- Memorandum of Understanding concerning Conservation Measures for Marine Turtles of the Atlantic Coast of Africa
- Memorandum of Understanding on the Conservation and Management of Marine Turtles and their Habitats of the Indian Ocean and South-East Asia
- Sea Turtle Association of Japan, Kuroshima Research Station
- Sea Turtle Conservancy
- Sea turtle migration
- Sea Turtles 911
- Shrimp-Turtle Case
- Threats to sea turtles
- Brongersma, L.D. (1972). "European Atlantic Turtles". Zoologische Verhandelingen. 121: 1–318.
- Davidson, Osha Gray. (2001). Fire in the Turtle House: The Green Sea Turtle and the Fate of the Ocean. United States: United States of Public Affairs. ISBN 1-58648-199-1.
- Sizemore, Evelyn (2002). The Turtle Lady: Ila Fox Loetscher of South Padre. Plano, Texas: Republic of Texas Press. p. 220. ISBN 1-55622-896-1.
- Spotila, James R. (2004). Sea Turtles: A Complete Guide to Their Biology, Behavior, and Conservation. Baltimore: Johns Hopkins University Press. ISBN 0-8018-8007-6.
- Witherington, Blair E. (2006). Sea Turtles: An Extraordinary Natural History of Some Uncommon Turtles. St. Paul: Voyageur Press. ISBN 0-7603-2644-4.
- Hirayama R; Tong H (2003). "Osteopygis (Testudines: Cheloniidae) from the Lower Tertiary of the Ouled Abdoun phosphate basin, Morocco". Palaeontology. 46 (5): 845–56. doi:10.1111/1475-4983.00322.
- Rhodin, Anders G.J.; van Dijk, Peter Paul; Inverson, John B.; Shaffer, H. Bradley; Roger, Bour (2011-12-31). "Turtles of the world, 2011 update: Annotated checklist of taxonomy, synonymy, distribution and conservation status". Chelonian Research Monographs. 5. Archived from the original (PDF) on 2012-01-22.
- Avise, J. C.; Hamrick, J. L. (1996). Conservation Genetics. Springer. ISBN 0412055813.
- Fisheries, NOAA. "Sea Turtles :: NOAA Fisheries". www.nmfs.noaa.gov. Retrieved 2015-12-20.
- "Sea Turtles". Defenders of Wildlife. Retrieved 15 October 2015.
- "Sea Turtle Species". turtlehospital. Retrieved 29 August 2015.
- Mateus; et al. (2009). "The oldest African eucryptodiran turtle from the Cretaceous of Angola". Acta Palaeontologica Polonica. 54: 581–588. doi:10.4202/app.2008.0063.
- Kear BP; Lee MS (March 2006). "A primitive protostegid from Australia and early sea turtle evolution". Biology Letters. 2 (1): 116–9. doi:10.1098/rsbl.2005.0406. PMC . PMID 17148342.
- Carr, Archie (August 1987). "New Perspectives on the Pelagic Stage of Sea Turtle Development". Conservation Biology. Blackwell Publishing. 1 (2): 103–121. doi:10.1111/j.1523-1739.1987.tb00020.x. JSTOR 2385827.
- Brynner, Jeanna (19 September 2007). "Sea Turtles' Mystery Hideout Revealed". LiveScience. Imaginova Corp. Retrieved 20 September 2007.
- "WWF - Marine Turtles". Species Factsheets. World Wide Fund for Nature. 4 May 2007. Retrieved 13 September 2007.
- Jaffe, A. L.; Slater, G. J.; Alfaro, M. E. (2011). "The evolution of island gigantism and body size variation in tortoises and turtles" (PDF). Biology Letters. 7 (4): 558–561. doi:10.1098/rsbl.2010.1084. PMID 21270022.
- Audubon, Maria R. (1986) [First published 1897]. Audubon and His Journals: Dover Publications Reprint. New York: Scribner's Sons. pp. 373–375. ISBN 978-0-486-25144-8.
- Mrosovsky, N. (August 1982). "Sex ratio bias in hatchling sea turtles from artificially incubated eggs". Biological Conservation. 23 (4): 309–314. doi:10.1016/0006-3207(82)90087-8.
- Morreale, S.; Ruiz, G.; Spotila, J.; Standora, E. (11 June 1982). "Temperature-dependent sex determination: current practices threaten conservation of sea turtles". Science. 216 (4551): 1245–1247. doi:10.1126/science.7079758.
- Mrosovsky, N.; Hopkins-Murphy, S. R.; Richardson, J. I. (17 August 1984). "Sex Ratio of Sea Turtles: Seasonal Changes". Science. 225 (4663): 739–741. doi:10.1126/science.225.4663.739.
- Godfrey, Matthew H.; Barreto, R.; Mrosovsky, N. (December 1997). "Metabolically-Generated Heat of Developing Eggs and Its Potential Effect on Sex Ratio of Sea Turtle Hatchlings". Journal of Herpetology. 31 (4): 616. doi:10.2307/1565626.
- Ewert, Michael A.; Jackson, Dale R.; Nelson, Craig E. (15 September 1994). "Patterns of temperature-dependent sex determination in turtles". Journal of Experimental Zoology. 270 (1): 3–15. doi:10.1002/jez.1402700103.
- Standora, Edward; Spotila, James (Aug 5, 1985). "Temperature dependent sex determination in sea turtles". Copeia. 1985: 711–722. doi:10.2307/1444765. JSTOR 1444765.
- Janzen, Fredric J.; Tucker, John K.; Paukstis, Gary L. (2007). "Experimental analysis of an early life-history stage: direct or indirect selection on body size of hatchling turtles?" (PDF). Functional Ecology. 21 (1). doi:10.1111/j.1365-2435.2006.01220.x.
- Reich, Kimberly J.; Karen A. Bjorndal; Alan B. Bolten (18 September 2007). "The 'lost years' of green turtles: using stable isotopes to study cryptic lifestages". Biology Letters. 3 (6): 712–714. doi:10.1098/rsbl.2007.0394. PMC . PMID 17878144. Retrieved 20 September 2007.
- Nicolson, S.W.; P.L. Lutz (1989). "Salt gland function in the green sea turtle Chelonia mydas" (PDF). Journal of Experimental Biology. 144: 171–184.
- Reina RD; Jones TT; Spotila JR (July 2002). "Salt and water regulation by the leatherback sea turtle Dermochelys coriacea". Journal of Experimental Biology. 205 (13): 1853–60. PMID 12077161.
- Schmidt-Nielsen K; Fange R (1958). "Salt glands in marine reptiles". Nature. 182: 783–5. doi:10.1038/182783a0.
- Hudson, D.M.; Lutz, P.L. (1986). "Salt gland function in the leatherback sea turtle, Dermochelys coriacea". Copeia. 1986 (1): 247–249. doi:10.2307/1444922. JSTOR 1444922.
- Braun-McNeill, Joanne; Sasso, Christopher; Epperly, Sheryan; Rivero, Carlos (December 2008). "Feasibility of Using Sea Surface Temperature Imagery to Mitigate Cheloniid Sea Turtle – Fishery Interactions off the Coast of Northeastern USA" (PDF). Endangered Species Research. 5: 257–266. doi:10.3354/esr00145. Retrieved Dec 19, 2015.
- Green, Derek (March 1997). "Basking in Galapagos Green Turtles" (PDF). Proceedings of the 17th Annual Sea Turtle Symposium.
- Lutcavage, Molly E.; Lutz, Peter L. (1991-05-16). "Voluntary diving metabolism and ventilation in the loggerhead sea turtle". Journal of Experimental Marine Biology and Ecology. 147 (2): 287–296. doi:10.1016/0022-0981(91)90187-2.
- "Information About Sea Turtles: Frequently Asked Questions". Sea Turtle Conservancy. Retrieved 2015-10-15.
- Hochscheid, Sandra; Bentivegna, Flegra; Hays, Graeme C. (2005-03-22). "First records of dive durations for a hibernating sea turtle". Biology Letters. 1 (1): 82–86. doi:10.1098/rsbl.2004.0250. ISSN 1744-9561. PMC . PMID 17148134.
- Burbidge, Andrew A (2004). Threatened animals of Western Australia. Department of Conservation and Land Management. pp. 110, 114. ISBN 0-7307-5549-5.
- Bolten, A.B. (2003). "Loggerhead Turtle (Caretta caretta)". NOAA Fisheries. NOAA Fisheries. Archived from the original on May 27, 2010. Retrieved January 31, 2010.
- Barbour, Roger, Ernst, Carl, & Jeffrey Lovich. (1994). Turtles of the United States and Canada. Washington, DC: Smithsonian Institution Press.
- Ernst, C. H.; Lovich, J.E. (2009). Turtles of the United States and Canada (2 ed.). JHU Press. p. 50. ISBN 978-0-8018-9121-2. Retrieved May 27, 2010.
- Arthur, Karen; Boyle, Michelle; Limpus, Colin (June 30, 2008). "Ontogenetic Changes in Diet and Habitat Use in Green Sea Turtle (Chelonia mydas) Life History" (PDF). Marine Ecology Progress Series. 362: 303–311. doi:10.3354/meps07440. Retrieved Dec 20, 2015.
- Nishizawa, H.; Asahara, M.; Kamezaki, N.; Arai, N. (2010). "Differences in the skull morphology between juvenile and adult green turtles: implications for the ontogenetic diet shift". Current Herpetology. 29 (2): 97–101. doi:10.3105/018.029.0205.
- http://www.mindcomet.com, MindComet, Inc. -. "Diet & Eating Habits". seaworld.org. Retrieved 2016-04-27.
- "WWF - Leatherback turtle". Marine Turtles. World Wide Fund for Nature (WWF). 16 February 2007. Retrieved 9 September 2007.
- "Species Fact Sheet: Leatherback Sea Turtle". Caribbean Conservation Corporation & Sea Turtle Survival League. Caribbean Conservation Corporation. 29 December 2005. Retrieved 6 September 2007.
- Meylan, Anne (1988-01-22). "Spongivory in Hawksbill Turtles: A Diet of Glass". Science. 239 (4838): 393–395. doi:10.1126/science.239.4838.393. JSTOR 1700236. PMID 17836872.
- CITES (14 June 2006). "Appendices". Convention on International Trade in Endangered Species of Wild Flora and Fauna. Archived from the original (SHTML) on 3 February 2007. Retrieved 5 February 2007.
- UNEP-WCMC. "Eretmochelys imbricata A-301.003.003.001". UNEP-WCMC Species Database: CITES-Listed Species. United Nations Environment Programme - World Conservation Monitoring Centre. Archived from the original on September 29, 2007. Retrieved 5 February 2007.
- Schafer, Edward H. (1962). "Eating Turtles in Ancient China". Journal of the American Oriental Society. American Oriental Society. 82 (1): 73–74. doi:10.2307/595986. JSTOR 595986.
- Sam Settle, 1995. Marine Turtle Newsletter 68:8-13
- Heppel, Selina S.; Larry B. Crowder (June 1996). "Analysis of a Fisheries Model for Harvest of Hawksbill Sea Turtles (Eretmochelys imbricata)". Conservation Biology. Blackwell Publishing. 10 (3): 874–880. doi:10.1046/j.1523-1739.1996.10030874.x. JSTOR 2387111.
- Strieker, Gary (10 April 2001). "Tortoiseshell ban threatens Japanese tradition". CNN.com/sci-tech. Cable News Network LP, LLLP. Retrieved 2 March 2007.
- Casson, Lionel (1982). "Periplus Maris Erythraei: Notes on the Text". The Journal of Hellenic Studies. The Society for the Promotion of Hellenic Studies. 102: 204–206. doi:10.2307/631139. JSTOR 631139.
- Berrin, Katherine & Larco Museum. The Spirit of Ancient Peru:Treasures from the Museo Arqueológico Rafael Larco Herrera. New York: Thames and Hudson, 1997.
- Sea Turtles in Tortuguero National Park Costa Rica -Turtle Observation in Tortuguero Costa Rica
- Alden, John R. (25 October 1998). "Turtle Watch in Costa Rica". The New York Times.
- Why Care About Sea Turtles?, Sea Turtle Conservancy.
- "The IUCN Red List of Threatened Species". www.iucnredlist.org. Retrieved 2015-12-24.
- "Checklist of CITES species". checklist.cites.org. Retrieved 2015-12-24.
- United States Fish & Wildlife Service. "Endangered Species Program". Retrieved April 12, 2012.
- "Chelonia mydas (Green Turtle)". www.iucnredlist.org. Retrieved 2015-12-24.
- Fisheries, NOAA. "Green Turtle (Chelonia mydas) :: NOAA Fisheries". www.nmfs.noaa.gov. Retrieved 2015-12-24.
- "Caretta caretta (Loggerhead Turtle)". www.iucnredlist.org. Retrieved 2015-12-24.
- Fisheries, NOAA. "Loggerhead Turtle (Caretta caretta) :: NOAA Fisheries". www.nmfs.noaa.gov. Retrieved 2015-12-24.
- "Lepidochelys kempii (Atlantic Ridley, Gulf Ridley, Kemp's Ridley, Mexican Ridley)". www.iucnredlist.org. Retrieved 2015-12-24.
- Fisheries, NOAA. "Kemp's Ridley Turtle (Lepidochelys kempii) :: NOAA Fisheries". www.nmfs.noaa.gov. Retrieved 2015-12-24.
- "Lepidochelys olivacea (Olive Ridley, Pacific Ridley)". www.iucnredlist.org. Retrieved 2015-12-24.
- Fisheries, NOAA. "Olive Ridley Turtle (Lepidochelys olivacea) :: NOAA Fisheries". www.nmfs.noaa.gov. Retrieved 2015-12-24.
- "Eretmochelys imbricata (Hawksbill Turtle)". www.iucnredlist.org. Retrieved 2015-12-24.
- Fisheries, NOAA. "Hawksbill Turtle (Eretmochelys imbricata) :: NOAA Fisheries". www.nmfs.noaa.gov. Retrieved 2015-12-24.
- "Natator depressus (Flatback)". www.iucnredlist.org. Retrieved 2015-12-24.
- "Dermochelys coriacea (Coffin-back, Leatherback, Leatherback Sea Turtle, Leathery Turtle, Luth, Trunkback Turtle, Trunk Turtle)". www.iucnredlist.org. Retrieved 2015-12-24.
- Fisheries, NOAA. "Leatherback Turtle (Dermochelys coriacea) :: NOAA Fisheries". www.nmfs.noaa.gov. Retrieved 2015-12-24.
- Clarren, Rebecca (2008). "Night Life". Nature Conservancy. 58 (4): 32–43.
- Adraneda, Katherine (12 September 2007). "WWF urges RP to pursue case vs turtle poachers". Headlines. The Philippine Star. Retrieved 12 September 2007.[dead link]
- Bjorndal, Karen; Bowen, Brian; Chaloupka, M.; Crowder, L. B.; Heppell, S. S.; Jones, C. M.; Lutcavage, M. E.; Policansky, D.; et al. (2011). "Better science needed for restoration in the Gulf of Mexico" (PDF). Science. AAAS. 331 (6017): 537–538. doi:10.1126/science.1199935. PMID 21292956. Retrieved July 25, 2011.
- Witherington, B.E.; Kubilis, Anne; Brost, Beth; Meylan, Anne (2009). "Decreasing annual nest counts in a globally important loggerhead sea turtle population". Ecological Applications. Ecological Society of America. 19 (1): 30–54. doi:10.1890/08-0434.1. PMID 19323172.
- The National Research Council (2010). "Assessment of Sea Turtle Status and Trends: Integrating Demography and Abundance". Washington, DC: National Academies Press.
- Jaffé, R.; Peñaloza, C.; Barreto, G. R. (2008). "Monitoring an endangered freshwater turtle management program: effects of nest relocation on growth and locomotive performance of the giant South American turtle (Podocnemis expansa, Podocnemididae)". Chelonian Conservation and Biology. 7 (2): 213–222. doi:10.2744/CCB-0696.1.
- Wright, Sara. "Hilton Head Island sees record sea turtle nesting season." Bluffton Today (2010): n. pag. Web. 8 Dec 2010.
- "Natural." Sea Turtle Foundation. Sea Turtle Foundation, 2010. Web. 8 Dec 2010.
- Baker, Natural History and Behavior, pp. 8–16
- Heithaus, Michael R.; Wirsing, Aaron J.; Thomson, Jordan A.; Burkholder, Derek A. (2008). "A review of lethal and non-lethal effects of predators on adult marine turtles". Journal of Experimental Marine Biology and Ecology. 356 (1-2): 43–51. doi:10.1016/j.jembe.2007.12.013.
- Moniz, Jesse (3 February 2007). "Turtle conservation: It's now very much a political issue". News. The Royal Gazette Ltd.
- Scales, Helen (27 April 2007). "Glow Sticks May Lure Sea Turtles to Death". News. National Geographic News.
- NYSDEC. "Atlantic Hawksbill Sea Turtle Fact Sheet". Endangered Species Unit. Retrieved 7 February 2007.
- Bappa Majumdar (5 February 2007). "Fishermen blamed for turtle deaths in Bay of Bengal". Yahoo! Science News. Yahoo! Inc. Retrieved 6 February 2007.[dead link]
- Irene Kinan . 2006. Marine Turtle Newsletter 113:13-14
- O'Kelly-Lynch, Ruth. "Govt: Long-line fishing won't hurt birds".
- WEISS, KENNETH R. (2002-03-14). "Pope Asked to Call Sea Turtles 'Meat'". Los Angeles Times. ISSN 0458-3035. Retrieved 2015-12-22.
- Hawkes, LA; Broderick, AC; Godfrey, MH; Godley, BJ (2009). "Climate change and marine turtles". Endangered Species Research. 7: 137–154. doi:10.3354/esr00198.
- Hirsch, Masako (9 June 2010). "Gulf oil spill's effects on sea turtles examined". nola.com. Retrieved 17 May 2012.
- "Volunteer Opportunities." 2007. February 22, 2007. Marinemammalcenter.org
- Sea Turtle, Inc
- Zardus, J. D.; Hadfield, M. G. (2004). "Larval development and complemental males in Chelonibia testudinaria, a barnacle commensal with sea turtles". Journal of Crustacean Biology. 24 (3): 409–421. doi:10.1651/C-2476.
- Epibiont Research Cooperative. 2007. A synopsis of the literature on the turtle barnacle (Cirripedia: Balanomorpha: Coronuloidea) 1758-2007. Accessed 28 Nov 2012.
- A free ride under the sea: barnacles and baleen whales. Themes of Parasitology. 2012. Web. 28 Nov 2012.
- Barnacles. True Wild Life. 2011. Web. 28 Nov 2012.
|Wikimedia Commons has media related to Chelonioidea.|
|Wikispecies has information related to: Chelonioidea|