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Loggerhead sea turtle

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Loggerhead sea turtle
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Reptilia
Subclass:
Anapsida
Order:
Testudines
Family:
Cheloniidae
Genus:
Caretta

Species:
C. caretta
Binomial name
Caretta caretta
Linnaeus, 1758
Range of Caretta caretta

The loggerhead turtle (Caretta caretta) also commonly called the loggerhead sea turtle, is the world's most-studied and well-known sea-turtle.[1] It inhabits the Indian, Pacific and Atlantic Oceans. It is the only member of the genus Caretta, which is a latinization of the French "caret", meaning turtle, tortoise, or sea turtle. Adults weigh from 77 to 160 kilograms (170 to 353 lb) and measure 79 to 120 centimetres (31 to 47 in).[2] Their shell is a reddish brown color, and their skin ranges from yellow to brown. The loggerhead sea turtle is the world's largest hard-shelled turtle.[3] Currently, the loggerhead is listed as endangered by the IUCN.[4]

Taxonomy

Carolus Linnaeus first named the loggerhead, calling it Testudo caretta.[5] Thirty-five other names emerged over the following two centuries, however Caretta caretta has prevailed.[5] C. caretta gets its common name, loggerhead, from the large head.[4] Two subspecies are recognized: C. caretta gigas which inhabits the Indian and Pacific Oceans, and C. caretta caretta which inhabits the Atlantic and the Mediterranean sea.[5] The loggerhead turtle belongs to the family Cheloniidae. All sea turtles, with the exception of the leatherback, are members of this family.[6]

Distribution

The loggerhead has cosmopolitan distribution, nesting over the broadest geographical range of any sea turtle[7]. The loggerhead inhabits the Atlantic, Indian, and Pacific oceans, as well as the Mediterranean Sea.

In the Atlantic Ocean, the greatest concentration of loggerheads is along the southeastern coast of North America and in the Gulf of Mexico.[7] Very few are found along the European and African coastlines.[8] Florida is the most popular nesting site with over 67,000 nests built per year.[8] Nesting extends as far north as Virginia, as far south as Brazil, and as far east as the Cape Verde Islands.[8] The Cape Verde Islands are the only significant nesting site on the eastern side of the Atlantic. In the Northwestern Atlantic Ocean, age plays a factor in habitat preference. Juveniles are more frequently found in shallow estuarine habitats with limited ocean access compared to non-nesting adults.[9] Loggerheads found in the Atlantic Ocean feed from Canada to Brazil.[7]

In the Indian Ocean, loggerheads feed along the coastlines of Africa, the Arabian Peninsula, and in the Arabian Sea.[10] Along the African coastline, the loggerhead nests from Mozambique's Bazaruto Archipelago to South Africa's St Lucia estuary.[11] The largest Indian Ocean nesting site is Oman, on the Arabian Peninsula, which hosts around 15,000 nests, giving it the second largest nesting population of loggerheads in the world.[10] Western Australia and Southern Africa are other notable nesting areas.

Pacific Loggerheads live in temperate to tropical regions.[11] They forage in the East China Sea, the southwestern Pacific, and along the Baja Peninsula. Eastern Australia and Japan are the major Pacific nesting areas. Pacific loggerheads occasionally nest in Vanuatu and Tokelau. Yakushima Island is the most important site with three nesting grounds that 40% of all nearby loggerheads visit. Little nesting occurs on the eastern Pacific coastline; however, thousands of loggerheads live there during the summers.[10] Post-nesting females often find homes in the East China Sea, while the Kuroshio Extension Bifurcation region as well as the coast of Baja California provide important juvenile foraging areas.[11] Hatchlings migrate from the east Pacific to the Mexican coastline and return later as sub-adults.[10]

The Mediterranean is a nursery for juveniles. Almost 45% of the Mediterranean juvenile population has migrated from the Atlantic.[8] Loggerheads feed in the Alboran Sea and the Adriatic Sea.[8] Greece is the most popular nesting site along the Mediterranean with more than 3,000 nests per year.[10] In fact, Greek authorities do not allow planes to take off or land at night in Zakynthos due to the turtles nesting.[12] The coastlines of Cyprus and Turkey are also common nesting sites.[10]

These distinct populations of loggerheads have unique characteristics and genetic differences. For example, Mediterranean loggerheads are smaller, on average, than Atlantic Ocean loggerheads.[10] Around three million years ago, during the Pliocene epoch, the Atlantic and Indian-Pacific populations split due to the formation of Central America. Currents that originally flowed between the Atlantic and Pacific oceans ceased when the Earth entered an ice age. The Atlantic Ocean surrounding South Africa decreased in temperature to a point which was too cold for loggerheads to inhabit, thus isolating the populations.[13]

Anatomy and Morphology

Photo of the underside of a loggerhead turtle.
The plastron of a loggerhead is pale yellow. Gular scutes are clearly visible.

Adult loggerhead sea turtles have a weight range of 77 to 160 kilograms (170 to 353 lb) and a length range of 79 to 120 centimetres (31 to 47 in).[2] On average, they weigh 115 kilograms (254 lb) and measure 92 centimetres (36 in).[14] The head and carapace (upper shell) range from a yellow-orange to a reddish-brown, while the plastron (underside) is typically pale yellow.[14] The turtle's neck and sides are brown on the tops and yellow on the sides and bottom.[4] Hatchlings range in coloration from light brown to almost black and lack the adult's distinct yellows and reds.[14] They measure approximately 4.6 centimetres (1.8 in) at birth, and weigh about 20 grams (0.71 oz).[4] The gender of loggerheads is not apparent through external morphology.[15]

The turtle's shell is divided into two sections: carapace and plastron. The carapace is further divided into large plates, or scutes.[14] Typically, there are 11 or 12 pairs of marginal scutes which rim the carapace.[5] Five vertebral scutes run down the carapace's midline while five pairs of costal scutes border them.[16] The nuchal scute is located at the base of the head.[16] The carapace connects to the plastron by 3 pairs of inframarginal scutes forming the bridge of the shell.[16] The plastron features paired gular, humeral, pectoral, abdominal, femoral, and anal scutes.[5] The shell serves as external armor; however, loggerhead turtles cannot retract their head or flippers into their shells.[17][18]

More than 100 species of animals from 13 phyla as well as 37 kinds of algae live on loggerheads' backs.[19] These parasitic organisms, which increase drag, offer no known benefit to the turtle, although it has been suggested that the dulling effect of organisms on shell color improves camouflaging ability.[19]

The loggerhead has several adaptations for its salt water environment. Salt glands near the turtle's eyes allow it to eliminate salt ingested while drinking ocean water. Loggerheads can appear to be "crying" when secreting the excess salt.[17]

Ecology

Habitat

The loggerhead sea turtle spends most of its life in the open ocean and in shallow coastal waters. Turtles rarely come ashore, with the exception of the females brief visits to construct nests and deposit eggs. After hatching, the young turtles return to the open ocean, living in floating mats of sargassum algae.[20] Adults and juveniles live along the continental shelf as well as in shallow coastal estuaries.[21]

A loggerhead skull and lower jaw.
The loggerhead has a strong jaw useful for crushing food.

Predators

Raccoons are the primary predators of loggerhead nests, and can be extremely destructive. Undisturbed nests have a hatching success rate of 60 percent or more.[22] On two barrier islands in South Carolina, raccoons destroyed more than 80 percent of loggerhead nests.[22] In Cape Sable, Florida, raccoons destroyed 75-85 percent of the nests.[22] The side striped jackal and honey badgers are common predators of loggerheads inSouth Africa.[22]

Feeding

The loggerhead turtle is a carnivore, feeding mainly on bottom dwelling invertebrates including molluscs and crustaceans. They crush these invertebrates with their large and powerful jaws.[4] During migration through the open sea, loggerheads eat jellyfish, floating molluscs, floating egg clusters, squid, and flying fish.[4]

Female-female aggression

Female-female aggression is not widely documented, especially in marine vertebrates. However, it is common among loggerheads. Ritualized aggression escalates from passive threat displays to combat. This conflict primarily occurs over access to feeding grounds.[23]

Escalation typically follows four steps. Initial contact is stimulated by visual or tactile cues.[23] The second stage involves passive confrontations characterized by wide head-tail circling.[23] They begin aggressive confrontation[23] when one turtle ceases to circle and directly faces the other.[23] Sparring occurs with turtles snapping at each other’s jaws.[23] The final stage, separation, is either mutual, with both turtles swimming away in opposite directions, or involves chasing one out of the immediate vicinity.[23]

Escalation is determined by several factors including: hormone levels, energy expenditure, expected outcome, and importance of location.[23] At all stages an upright tail shows willingness to escalate, while a curled tail shows willingness to submit.[23] Because higher aggression is metabolically costly and potentially debilitating, contact is much more likely to escalate when the conflict is over access to good foraging grounds.[23]

Life history

Photo of a loggerhead hatchlings being held.
Hatchling loggerhead turtles.

Early life

The loggerhead's gender is dictated by the temperature of the underground nest. Incubation temperatures generally range from 26–32 °C (79–90 °F). Cooler temperatures produce males; warmer ones, females.[3] After incubating for approximately 80 days beneath the sand, hatchlings dig to the surface and make their way to the sea. This usually occurs at night when there are fewer predators to catch them. Hatchlings are drawn toward the reflection of the moon and stars off the water surface, however, artificial lighting can lead hatchlings astray.[24] Hatchlings from eggs in the middle of the clutch tend to be the largest, grow the fastest, and be the most active during the first few days of sea life.[25]

Hatchlings can lose up to twenty percent of their body mass due to evaporation of water on the journey from nest to ocean.[26] Hatchlings initially use the undertow to push them five to ten yards away from the shore.[26] Once in the ocean, hatchling loggerheads swim for about 20 hours, bringing them far offshore.[14] Loggerhead turtles have an iron compound, magnetite, that is attracted to the earth's north pole.[27] They use this magnetite to find a sense of direction. Many hatchlings use Sargassum in the open ocean as protection until they reach 45 centimetres (18 in).[14] Hatchling loggerheads live in this pelagic environment until they reach juvenile age and migrate to nearshore waters.[14]

Maturation

Photo of a loggerhead swimming above a reef.
A mature loggerhead sea turtle.

When ocean waters cool, loggerheads must migrate to warmer areas or hibernate to some degree. In the coldest months, loggerheads submerge for up to seven hours at a time, emerging for only seven minutes to breathe. Although outdone by freshwater turtles, these are among the longest recorded dives for any air-breathing marine vertebrate.[28]

During their migration, juvenile loggerheads have the ability to use both magnetic cues and visual cues.[29] When both magnetic and visual aids are available, they are used in conjunction; If one aid is not available the other suffices.[29]

Loggerheads mature sexually at around age 35.[4] Nesting loggerheads have a straight carapace length of 70–109 centimetres (28–43 in).[30] Seventy centimeters is the minimum size for breeding, although not all loggerheads begin breeding at this size. Therefore carapace length is not a reliable indicator of sexual maturity.[30] Loggerheads that reach adulthood typically live more than 30 years, and often live past 50 years.

Like all marine turtles, the loggerhead prepares for reproduction in its foraging area. This takes place several years before the loggerhead migrates to a mating area.[30]

Reproduction

The loggerhead mating period lasts up to six weeks.[31] Loggerhead turtles court their mates, however these behaviors have not been thoroughly examined.[32] Nuzzling, biting, head movements, and flipper movements are forms of male courtship behavior.[32] Females produce cloacal pheromones to suggest reproductive ability.[32] Males approach females and attempt to mount them, while females resist. The male and female circle each other. If the male has competitors, the female may let the males struggle with each other. The winner then mounts the female. Other courting males bite the male during mating, damaging his flippers and tail, possibly exposing his bones, requiring weeks to heal. Such damage can cause the male to dismount.[32] The male's curved claws damage the shoulders of the female's shell when he mounts her. He may injure her by biting her neck during mating.[32]

During the mating period, females produces an average of 3.9 egg clutches and then become quiescent, producing no eggs for an average two to three years.[31][22] Female loggerheads first reproduce from ages 28-33 in Southeastern United States and Australia, and from ages 17 to 30 in South Africa. Age at first reproduction in the Mediterranean, Oman, Japan, and Brazil are unknown.[33] Unlike other sea turtles, courtship and mating usually do not take place near the nesting beach but rather along migration routes between feeding and breeding grounds.[32] Recent evidence indicates that ovulation in loggerheads is mating-induced.[34] This is unique, as mating-induced ovulation is rare outside of mammals.[34] In the Mediterranean, loggerheads mate from late March to early June. The nesting season peaks in June and July, but varies by nesting beach.[35]

Loggerheads may display multiple paternity.[36] A single clutch may have as many as five fathers, each contributing sperm to a portion of the clutch.[36] Multiple paternity and female size are positively correlated.[36] Two hypotheses account for this correlation. One states that males favor large females due to perceived higher fecundity.[36] Another states that because larger females are able to swim more quickly to mating grounds, they have a longer mating period.[36] Multiple paternity is possible due to sperm storage. The female can store sperm from multiple males in her oviducts until ovulation.[37]

All sea turtles have similar basic nesting behaviors. Females return to lay eggs at intervals of 12-17 days during nesting season, on or near the beach where they hatched.[38][22] They haul out of the water, climb the beach, excavate a body pit, lay eggs, fill the egg chamber, fill the body pit, and finally return to sea.[39] This process takes 1-2 hours and occurs in open sand areas or on top of sand dunes.[22] The nesting area must be selected carefully because it affects characteristics such as fitness, emergence ratio, and vulnerability to nest predators.[40] Clutch size ranges from 7–15 centimetres (2.8–5.9 in). Each egg is roughly the size and shape of a ping-pong ball.

A female loggerhead sea turtle from the back, laying eggs into the hole it has dug.
Loggerhead Sea Turtle laying eggs.

Loggerhead turtles are the most common nesting sea turtle in the United States. They nest from Texas to North Carolina, requiring soft sandy beaches with little or no light pollution. The largest concentration is in south Florida.

Importance to humans

Loggerhead Sea Turtles were once intensively hunted for meat and eggs. Turtle meat and eggs in general are widely eaten today despite international regulations.[41] In Mexico, turtle eggs are a common meal.[42] Locals claim that the egg is an aphrodisiac.[42] However, high levels of toxic metals build up through bioaccumulation and harmful bacteria such as Pseudomonas aeruginosa and Serratia marcescens in turtle meat or eggs can cause serious illness.[41][43]

Loggerhead turtles offer opportunities for ecotourism that bring revenue to nearby communities.[17]

Conservation

Threats

An orange diamond sign with the words "Loggerhead Turtle Nesting Area" is blocking off a roped-off area on the beach where a loggerhead has laid eggs.
Loggerhead Sea Turtle nest roped off as part of the Sea Turtle Protection Project on Hilton Head Island.

Due to the loggerhead's slow sexual maturation, high survival rates are essential. For this reason, factors posing mild dangers to most marine populations may have exaggerated effects on loggerheads.[44]

Human activity

Many human activities have negative effects on loggerheads. Fishing gear is currently the biggest threat to loggerheads in the open ocean. Most commonly, they become entangled in longlines or gillnets. They may also become stuck in traps, pots, trawls, and dredges.[4]Caught in this unattended equipment, loggerheads risk serious injury or drowning when they can't return to the surface to breathe. Turtle excluder devices for nets and other traps help prevent them from being caught underwater. Since loggerheads spend a significant portion of their lives in open ocean environments, floating debris such as plastic pellets and abandoned fishing gear can be unintentionally ingested.[45]

Artificial lighting threatens loggerhead hatchlings, contributing to thousands of deaths per year. Hatchlings crawl to the water as soon as they emerge from their underground nest. They are guided toward the ocean by the reflection of the moon and stars off the water's surface.[24] Artificial lighting may cause the turtles to navigate inland, away from the protective waters, exposing them to dehydration and predation as the sun rises.[24][46] Optimum nesting beaches are open sand beaches above the high tide line. However, beach development deprives them of suitable nesting areas, forcing them to nest closer to the surf.[22] Urbanization often leads to the siltation of sandy beaches, decreasing their viability.[22]

Docks and marinas can destroy near shore habitats. Boat traffic and dredging can degrade habitat and can also injure or kill turtles when boats collide with turtles at or near the surface.[45]

Loggerheads compete with humans for the invertebrates they eat.[44]

Disease

Fibropapillomatosis disease threatens loggerheads. It is a herpes-type virus which causes internal and external tumors. These tumors disrupt essential behaviors and, if on the eyes, cause permanent blindness.[45] Trematodes of the family Spirorchiidae inhabit tissues throughout the body of the loggerhead including vital organs such as the heart and the brain.[47] Trematode infection can be highly debilitating, for example, inflammatory trematode lesions can cause endocarditis and neurological disease.[47] A nematode, Angiostoma carettae, also infects loggerheads.[48] The nematodes cause histologic lesions in the respiratory tract.[48]

Conservation Efforts

A Loggerhead sea turtle escapes a circular fisherman's net via a TED.
Loggerhead Sea Turtle escapes from fishing net through aTurtle Excluder Device (TED).

Since the loggerhead occupies such a broad range, successful conservation requires efforts from multiple countries.[4]

Loggerhead turtles are classified as endangered by the International Union for the Conservation of Nature and are listed under Appendix I of the Convention on International Trade in Endangered Species, making international trade illegal.[4] In the United States, the U.S. Fish and Wildlife Service (FWS) and National Marine Fisheries Service (NMFS) classify them as a threatened species under the Endangered Species Act.[4] Loggerheads are listed as endangered under both Australia's Environment Protection and Biodiversity Conservation Act 1999 and Queensland's Nature Conservation Act 1992. Annex 2 of the Specially Protected Areas and Wildlife (SPAW) Protocol of the Cartagena Convention also protects them. NMFS and FWS hold joint jurisdiction over them in the U.S. NMFS has worked with the shrimp trawling industry to develop TEDs that can exclude even the largest turtles. These devices are mandatory for all shrimp trawlers.[4]

In many places during the nesting season, workers and volunteers from organizations such as the Fripp Island, South Carolina Turtle Patrol [49] search the coastline for nests. They uncover them and count the eggs, if necessary relocate them for protection from threats such as high spring tides and predators. The nests are checked daily for disturbances. Several days after eggs hatch, the workers tally hatched eggs, undeveloped eggs, and dead hatchlings. Any remaining live hatchlings are either released or taken to research facilities. Typically, those that lack the vitality to hatch and climb to the surface would have died by this point.[50] Hatchlings use the journey from nest to ocean to build strength for the coming swim. Helping them to reach the ocean bypasses this strength building exercise and lowers their chances of survival.[50]

Plastic fencing can exclude predators such as raccoons or even dogs. The fence's gauge must be large enough to allow the hatchlings to pass through without difficulty but small enough to prevent predators from reaching the eggs.

Further reading

  • Bolten, Alan B.; Witherington, Blair E., eds. (2003). Loggerhead Sea Turtles. Washington, D.C.: Smithsonian Books.
  • Lutz, Peter L.; Musick, John A.; Wyneken, Jeanette (1997). The Biology of Sea Turtles. Vol. 1. Boca Raton, Florida: CRC Press.
  • Lutz, Peter L.; Musick, John A.; Wyneken, Jeanette (2003). The Biology of Sea Turtles. Vol. 2. Boca Raton, Florida: CRC Press.
  • Gulko, D.; Eckert, K.L. (2004). Sea Turtles: An Ecological Guide. Honolulu, Hawai’i: Mutual Publishing.

Notes

  1. ^ a b Spotila 2004, p. 163 harvnb error: multiple targets (2×): CITEREFSpotila2004 (help)
  2. ^ a b c "Loggerhead Sea Turtle (Caretta caretta)". Virginia: Virginia Herpetological Society. Retrieved 2010-02-15.
  3. ^ a b c MarineBio (March). "Caretta caretta Loggerhead Sea Turtle". Retrieved March 2, 2010. {{cite web}}: Check date values in: |date= and |year= / |date= mismatch (help)
  4. ^ a b c d e f g h i j k l m Bolten, A.B. (2003). "Loggerhead Turtle (Caretta caretta)". NOAA Fisheries. NOAA Fisheries. Retrieved January 31, 2010.
  5. ^ a b c d e f Conant 2009, p. 7 harvnb error: multiple targets (2×): CITEREFConant2009 (help)
  6. ^ a b Wynne 1999, p. 97
  7. ^ a b c d Spotila 2004, p. 164 harvnb error: multiple targets (2×): CITEREFSpotila2004 (help)
  8. ^ a b c d e f Spotila 2004, p. 165 harvnb error: multiple targets (2×): CITEREFSpotila2004 (help)
  9. ^ a b Conant 2009, p. 11 harvnb error: multiple targets (2×): CITEREFConant2009 (help)
  10. ^ a b c d e f g h Spotila 2004, p. 166 harvnb error: multiple targets (2×): CITEREFSpotila2004 (help)
  11. ^ a b c d Conant 2009, p. 8 harvnb error: multiple targets (2×): CITEREFConant2009 (help)
  12. ^ a b "Zakynthos Airport". 2010. Retrieved April 12, 2010. Night flights are banned on Zakynthos, so as not to disturb the endangered Caretta Caretta turtles which nest their eggs on the beaches of Zante.
  13. ^ a b Spotila 2004, p. 167 harvnb error: multiple targets (2×): CITEREFSpotila2004 (help)
  14. ^ a b c d e f g h Wynne 1999, p. 104
  15. ^ a b Wynne 1999, p. 98
  16. ^ a b c d Wynne 1999, p. 110
  17. ^ a b c d Duermit, Liz (2008). "Caretta caretta loggerhead sea turtle". University of Michigan. {{cite web}}: Cite has empty unknown parameter: |coauthors= (help)
  18. ^ a b Coastal Carolina University (March 2010). "Loggerhead Anatomy". Center for Marine and Wetland Centers. Coastal Carolina University. Retrieved April 1, 2010. {{cite web}}: Cite has empty unknown parameter: |coauthors= (help)
  19. ^ a b c Spotila 2004, p. 177 harvnb error: multiple targets (2×): CITEREFSpotila2004 (help)
  20. ^ a b Spotila 2004, p. 172 harvnb error: multiple targets (2×): CITEREFSpotila2004 (help)
  21. ^ a b Spotila 2004, p. 174 harvnb error: multiple targets (2×): CITEREFSpotila2004 (help)
  22. ^ a b c d e f g h i j Spotila 2004, p. 170 harvnb error: multiple targets (2×): CITEREFSpotila2004 (help)
  23. ^ a b c d e f g h i j k Schofield, Gail (2007). "Female-femmale aggressions: structure of interaction and outcome in loggerhead sea turtles". Marine Ecology. {{cite web}}: Cite has empty unknown parameter: |coauthors= (help); Missing or empty |url= (help)
  24. ^ a b c d Fish and Wildlife Research Institute (September 2009). "Artificial Lighting and Sea Turtle Hatchling Behavior". Florida Fish and Wildlife Conservation Commission. Coastal Carolina University. Retrieved April 1, 2010. {{cite web}}: Cite has empty unknown parameter: |coauthors= (help)
  25. ^ a b Spotila 2004, p. 171 harvnb error: multiple targets (2×): CITEREFSpotila2004 (help)
  26. ^ a b c Spotila 2004, p. 21 harvnb error: multiple targets (2×): CITEREFSpotila2004 (help)
  27. ^ a b Spotila 2004, p. 22 harvnb error: multiple targets (2×): CITEREFSpotila2004 (help)
  28. ^ a b Hochscheid, S. (2005). "First Records of Dive Durations for a Hibernating Sea Turtle". Biol. Lett. 1 (1): 82–6. doi:10.1098/rsbl.2004.0250. PMC 1629053. PMID 17148134. Retrieved 2 December 2009. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  29. ^ a b c Avens, Larisa (2003). "Use of multiple orientation cues by juvenile loggerhead sea turtles Caretta caretta". The Journal of Experimental Biology. {{cite web}}: Cite has empty unknown parameter: |coauthors= (help); Missing or empty |url= (help)
  30. ^ a b c d Miller 2000, p. 5
  31. ^ a b c Miller 2000, p. 4
  32. ^ a b c d e f g Miller 2000, p. 6
  33. ^ a b Spotila 2004, p. 16 harvnb error: multiple targets (2×): CITEREFSpotila2004 (help)
  34. ^ a b c Manire, Charles (2008). "Mating-induced ovulation in loggerhead sea turtles, Caretta caretta". Zoo Biology. {{cite web}}: Cite has empty unknown parameter: |coauthors= (help)
  35. ^ a b Miller 2000, p. 9
  36. ^ a b c d e f Zbinden, Judith (September 2007). "High frequency of multiple paternity in the largest rookery of Mediterranean loggerhead sea turtles". Molecular Ecology. {{cite web}}: Cite has empty unknown parameter: |coauthors= (help)
  37. ^ a b Pearce, D.E. (2001). "Turtle Behavior Systems: Behavior, Sperm Storage, and Genetic Paternity". The Journal of Heredity. Retrieved April 29, 2010. {{cite web}}: Cite has empty unknown parameter: |coauthors= (help)
  38. ^ a b Miller 2000, p. 29
  39. ^ a b Miller 2000, p. 13
  40. ^ a b Miller 2000, p. 10
  41. ^ a b c Aguirre, A.; Gardner, S. (July 12). "Hazards Associated with the Consumption of Sea Turtle Meat and Eggs: A Review for Health Care Workers and the General Public". Retrieved March 2, 2010. {{cite web}}: Check date values in: |date= and |year= / |date= mismatch (help)
  42. ^ a b c Dellios, Hugh (September 18). "Mexico Cracks Open Myth of Sea Turtle Eggs". Retrieved March 2, 2010. {{cite web}}: Check date values in: |date= and |year= / |date= mismatch (help)
  43. ^ a b Craven, Kathryn; Taylor, Judy (September 11). "Identification of Bacterial Isolates from Unhatched Loggerhead (Caretta caretta) Sea Turtle Eggs in Georgia, USA". Retrieved March 16, 2010. {{cite web}}: Check date values in: |date= and |year= / |date= mismatch (help)
  44. ^ a b c Spotila 2004, p. 178 harvnb error: multiple targets (2×): CITEREFSpotila2004 (help)
  45. ^ a b c d NOAA Fisheries (2010). "Threats to Marine Turtles". Endangered marine animal preservation. NOAA Fisheries Office of Protected Resources. Retrieved February 7, 2010. {{cite web}}: Cite has empty unknown parameter: |coauthors= (help)
  46. ^ a b Coastal Carolina University (March 2010). "Threats to Sea Turtle". Center for Marine and Wetland Centers. Coastal Carolina University. Retrieved April 1, 2010. {{cite web}}: Cite has empty unknown parameter: |coauthors= (help)
  47. ^ a b c Flint, Mark (November 2009). "Postmortem diagnostic investigation of disease in free-ranging marine turtle populations: a review of common pathologic findings and protocols". Journal of Veterinary Diagnostic Investigation. {{cite web}}: Cite has empty unknown parameter: |coauthors= (help); Missing or empty |url= (help)
  48. ^ a b c Manire, Charles (March 2008). "Lungworm infection in three loggerhead sea turtles, Caretta caretta". Journal of Zoo and Wildlife Medicine. {{cite web}}: Cite has empty unknown parameter: |coauthors= (help)
  49. ^ a b Natoli, A (December 17, 2002). "Fripp Island Patrol Mission Statement". Fripp Island Patrol. {{cite web}}: Cite has empty unknown parameter: |coauthors= (help)
  50. ^ a b c Conant 2009, p. 13 harvnb error: multiple targets (2×): CITEREFConant2009 (help)
  51. ^ Wynne 1999, p. 105
  52. ^ Basu, Rebecca (1 March 2010). "Winter is culprit in manatee death toll". Melbourne, Florida: Florida Today. pp. 3A.
  53. ^ Lever, Anna-Marie (2008-06-30). "Turtles return home after UK stay". BBC News.
  54. ^ Hulin, Vincent (June 2009). "Temperature-dependent sex determination and global change: are some species at greater risk?". Population Ecology. {{cite web}}: Cite has empty unknown parameter: |coauthors= (help); Missing or empty |url= (help)
  55. ^ Parker, Denise; Cooke, William (January 1). "Diet of oceanic loggerhead sea turtles (Caretta caretta) in the central North Pacific". Retrieved May 3, 2010. {{cite web}}: Check date values in: |date= and |year= / |date= mismatch (help)

References

Wikispecies has information related to Caretta caretta.
Wikimedia Commons has media related to Loggerhead Sea Turtle.
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