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Loggerhead sea turtle

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The 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 sea turtle (Caretta caretta) is a sea turtle, the only member of the genus Caretta. It is the world's most-studied and best-known sea-turtle.[1] The genus name "Caretta" is a latinization of the French "caret", meaning turtle, tortoise, or sea turtle.[2] A loggerhead sea turtle reportedly can reach Template:Lb to kg.[3] Their shell is a reddish brown color, and their skin is yellow/brown. They are named for their disproportionately large head. They are the state reptile of South Carolina.[4]

Taxonomy

Two subspecies are recognized: C. caretta gigas, inhabits the Indian and Pacific Oceans, and C. caretta caretta, the Atlantic loggerhead, also found in south Italy and the Greek islands of Zakynthos, Kefalonia, Crete, and the Peloponnese and in Dalyan in southwestern Turkey. (see June Haimoff).

C. caretta gets its name from its large head that supports the jaws necessary for crushing exoskeletons/shells of prey such as conch.[5] Linnaeus first named the loggerhead, calling it Testudo caretta. Thirty-five other names emerged over the following two centuries, but Caretta caretta has prevailed.[6]

Range and distribution

Loggerheads are distributed throughout the world; They live in the Atlantic Ocean, Indian Ocean, Pacific Ocean, and the Mediterranean Sea.[1]

Atlantic Ocean

The greatest concentration of loggerheads is along the southeastern coast of North America and in the Gulf of Mexico.[1] Very few loggerheads are found along the European and African coastlines.[1] Florida is the most popular nesting site with over 67,000 nests per year. Nesting extends as far north as Virginia, as far south as Brazil, and as far east as the Cape Verde Islands.[1] The Cape Verde Islands are the only significant nesting site on the eastern side of the Atlantic.

Indian Ocean

Indian Ocean loggerheads feed along the coastlines of Africa, the Arabian Peninsula, and in the Arabian Sea.[1] The largest population is located near the coast of western Australia.[1] The largest nesting site, Oman, is located on the Arabian Peninsula and hosts around 15,000 nests annually.[1] Western Australia and Southern Africa are other notable nesting areas.

Pacific Ocean

Loggerheads live in temperate to tropical regions of the Pacific Ocean.[6] Pacific loggerheads forage in the East China Sea, southwestern Pacific, and along the Baja Peninsula.[1] Eastern Australia and Japan are the major nesting areas.[1] Little nesting occurs on the eastern Pacific coastline however thousands of loggerheads live there during the summers.[1] There are also few breeding grounds in the northern and southern Pacific Ocean. In fact, loggerheads have been found to nest in Japan in the northern Pacific Ocean. Eastern Australia, New Caledonia, and rarely Vanuatu and Tokelau. Yakushima Island, Miyazaki, Minabe, and Atsumi beaches on the mainland provide important nesting areas. Yakushima Island is the most important of these, with three nesting grounds that 40% of all loggerheads near Japan visit. Post-nesting females often find homes in the East China Sea, while the Kuroshio Extension Bifurcation Region and the Coast of Baja California Sur, Mexico provide important juvenile foraging areas.[6] Hatchlings migrate from the east Pacific to Mexico only to return later as sub-adults.[1]

Mediterranean Sea

The Mediterranean is a nursery for juvenile loggerheads. Almost 45 percent of the juvenile population migrates from the Atlantic.[1] Loggerheads feed in the western and eastern basins of the Mediterranean, Alboran Sea and Adriatic Sea areas respectively.[1]

Greece is the most popular nesting site with more than 3,000 nests per year.[1] The coastlines of Cyprus and Turkey are also common nesting sites.[1]

Anatomy and Morphology

The adult typically has a carapace (shell) length of approximately Template:In to cm and weighs about Template:Lb to kg.[5] The flippers and carapace range from a dull brown to a reddish-brown, and the plastron (underside) is typically pale yellow.[5] The heart-shaped carapace is thick and bony and covered by non-overlapping scutes at the seam lines. Typically, there are 11 or 12 pairs of marginal scutes, 5 pairs of both vertebral and costal scutes, and a nuchal scute that contacts the costals. The carapace is connected to the plastron by 3 pairs of inframarginal scutes that lack pores. The plastron itself features paired gular, humeral, pectoral, abdominal, femoral, and anal scutes.[6] The turtle's neck and sides are brown on the tops and yellow on the sides and bottom.

Hatchlings vary in color from gray to brown, and lack the adults' distinct yellows and reds. They measure approximately Template:In to cm at birth, and weigh about .04 pounds (18 g).[5] The hatchlings' carapaces have 3 keels while the plastrons have 2.[6]

Ecology

Habitat

During its lifetime, the loggerhead sea turtle inhabits terrestrial, oceanic, and neritic ecosystems.[5] Upon birth, hatchlings enter the ocean and swim away from land for several days. The "post-hatchlings" then return to find a home in a local downwelling.[5] Downwellings are created when surface waters converge and feature floating material such as seaweed. They may stay there for months, feeding on floating material and occasionally swimming to keep from getting too cold. Eventually, they enter ocean currents farther from shore and move into the oceanic zone[5] where they remain until they become juveniles (between ages 7 and 12). They then move into the neritic zone and remain there until reaching adulthood.[5] The neritic zone is also an important area for adult foraging and inter-nesting habitats.[5]

Scientists in Hawaii use satellite transponders to track loggerhead sea turtles in the Northern Pacific Ocean.[7].

Feeding

The loggerhead mainly feeds on bottom dwelling invertebrates, including horseshoe crabs, clams, mussels, molluscs, crustaceans, fish, jellyfish, crabs, shrimp, Portuguese Man o' War and other small to medium-sized marine animals, which they crush with their large and powerful jaws. Their powerful jaw muscles allow them to easily crush shellfish.[5] During migration through the open sea, loggerheads eat jellyfishes, floating mollusks, floating egg clusters, squids, and flying fishes.[citation needed]

Life history

Photo of a baby loggerhead crawling across the sand.
Baby Loggerhead Sea Turtle.

Breeding

The female first creates a nest and then enters a mating period that can last up to six weeks.[8] Loggerhead sea turtles court their mates, but these behaviors have not been thoroughly examined. Nuzzling, biting, head movements, and flipper movements may be forms of male courtship behavior. Females may produce cloacal pheromones to suggest reproductive ability. Males approach females and attempt to mount them, while females resist. The male and female may circle each other. If the male has competitors, the female may leave the males to struggle with each other. The winner then mounts the female. Other courting males bite the male during mating, damaging his flippers and tail, sometimes to the point of exposing bones. Such damage can cause the male to dismount, requiring weeks to heal. 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.[8]

Over several months, females produces several egg clutches and then become quiescent, producing no eggs for an average two to three years. 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. In the Mediterranean, Loggerheads mate from late March to early June. The nesting season peaks in June and July, but varies by nesting beach.

All sea turtles have similar basic nesting behaviors. Females return to lay their eggs on or near the beach where they hatched. 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.[8] Clutch size ranges from 70 to 150. 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 sea turtle to nest in the United States. Loggerheads nest from Texas to North Carolina, requiring soft sandy beaches where there is little light pollution. The largest concentration is in south Florida. Florida statistics since 1998 describe its lowest nesting levels in 17 years, declining from 85,988 nests in 1998 to approximately 45,084 in 2007.[9]

Early life

After incubating for approximately 80 days, hatchlings emerge, usually at night when predation is reduced. Hatchlings average about Template:In to cm in length and weigh around 20 grams (0.71 oz) at birth.[5]

Maturation

Once in the ocean, Atlantic turtles use ocean currents to travel to the Sargasso Sea using the Sargassum as protection until they mature.[10]

An alternative to migration is hibernation to varying degrees as the water cools. By February they submerge for up to seven hours at a time, emerging for only seven minutes to breathe. Although outdone by freshwater turtles, these are the longest recorded dives for any air-breathing marine vertebrate.[11]

Loggerheads mature sexually at around age 35.[5] Nesting loggerheads have a straight caraprace length of 70–109 centimetres (28–43 in). Seventy is the minimum size for breeding. However, not all loggerheads begin nesting after reaching minimum size. Therefore carapace length is not a good indicator of sexual maturity.[8] Most loggerheads that reach adulthood 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.[8]

Importance to humans

Loggerhead Sea Turtles were once intensively hunted for their meat and eggs. Their fat was used in cosmetics and medication. Their shells were used to make items such as combs. As a result, C. caretta is now internationally protected.

Conservation

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

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. In the United States, the U.S. Fish and Wildlife Service and National Marine Fisheries Service classify them as a threatened species under the Endangered Species Act.[12] Loggerheads are listed as Endangered under both Australia's Environment Protection and Biodiversity Conservation Act 1999 and Queensland's Nature Conservation Act 1992.


Today the main threat to adults lies in shrimp trawlers and crab fishing nets, to which many loggerheads annually fall victim.[13] Adults are often injured by boat strikes and by swallowing fish hooks or getting caught in nets. Internationally, animal protection organizations monitor and protect the turtles' nesting grounds in Turkey,[14] Greece[15], Bonaire, and Costa Rica.

The turtles inhabit the Italian islands of Lampedusa andLinosa, off the coast of Sicily, and in Calabria, where they are particularly endangered. They also nest on the beaches of Cyprus, especially Akamas and Alagadi Beach.[16]

In many places during the nesting season, workers search the coastline for nests. They uncover the nest and count its eggs. If necessary they relocate it to protect it from humans and other threats. Plastic fencing can protect eggs from large predators such as raccoons or even dogs. The fence's gauge must be large enough to allow the hatchlings to pass through without difficulty. The nests are checked daily for disturbances. Several days after eggs hatch, the workers examine the nest, tallying hatched eggs, undeveloped eggs, and dead hatchlings. Any remaining live hatchlings are either raised and released or taken to research facilities. Those that appear strong and healthy may be immediately released to the ocean. Typically, those that lacked the strength to hatch and climb to the surface by that point would have died otherwise.

Hatchlings use the journey from nest to ocean to build strength for the coming swim. Therefore, helping them to reach the ocean lowers their chances of survival.[citation needed] The Fripp Island, South Carolina Turtle Patrol each year arranges driftwood to guide the hatchlings towards the closest shoreline.

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.

Fishing gear is currently the biggest threat to loggerheads. They are most commonly caught in longlines and gillnets but have also been accidentally captured in traps, pots, trawls, and dredges.[5] Caught in this gear, loggerheads risk serious injury or drowning. Turtle excluder devices for nets and other gear help protect them.

Because hatchlings usually follow the brightest light to the ocean's edge, artificial lights can lead them astray.

Since loggerheads spend a significant portion of their lives in open ocean environments, floating debris such as plastic pellets and ghost fishing gear can be ingested and harm the loggerheads.[17]

Fibropapillomatosis disease has been a problem for loggerheads. It causes internal and external tumors that disrupt essential behaviors and, if on the eyes, permanent blindness.


See also

Footnotes

  1. ^ a b c d e f g h i j k l m n o p q Spotila, James R. (2004). Sea Turtles: A Complete Guide to their Biology, Behavior, and Conservation. Baltimore, Maryland: The Johns Hopkins University Press and Oakwood Arts. pp. 163–179. ISBN 0-8018-8007-6. {{cite book}}: line feed character in |publisher= at position 47 (help); line feed character in |title= at position 33 (help)
  2. ^ http:www.widecast.org/sea/definitions.cfm[dead link]
  3. ^ a b My Scribe (May 8, 2009). "Loggerhead Facts". Loggerhead preservation. KiawahTurtles. Retrieved February 4, 2010. {{cite web}}: Cite has empty unknown parameter: |coauthors= (help)
  4. ^ [1]
  5. ^ 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.
  6. ^ a b c d e f Terese, Conant (August 2009). LOGGERHEAD SEA TURTLE (CARETTA CARETTA) 2009 STATUS REVIEW UNDER THE U.S. ENDANGERED SPECIES ACT (PDF). Loggerhead Biological Review Team. p. 222. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); line feed character in |coauthors= at position 54 (help); line feed character in |title= at position 40 (help)
  7. ^ Dennis Hollier (August/September 2008). "Mapping the Void". Hana Hou!. {{cite web}}: Check date values in: |date= (help)CS1 maint: extra punctuation (link)
  8. ^ a b c d e f Miller, Jeffrey D.; Limpus, Colin J.; Godfrey, Matthew H. (in press), "Nest Site Selection, Oviposition, Eggs, Development, Hatching and Emergence of Loggerhead Turtles", in Bolten, Alan; Witherington, Blair (eds.), Biology and Conservation of Loggerhead Sea Turtle (PDF), University of Florida Press, retrieved February 2, 2010 {{citation}}: Check date values in: |year= (help); line feed character in |contribution= at position 5 (help); line feed character in |title= at position 43 (help)CS1 maint: year (link)
  9. ^ [2][dead link]
  10. ^ BBC NEWS | Science/Nature | Turtles return home after UK stay
  11. ^ 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. These represent the longest dives ever reported for a diving marine vertebrate. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  12. ^ [3]
  13. ^ [4]
  14. ^ "Loggerhead Turtles in the Dalyan River, Mulğa Province, Turkey, 2004". seaturtle.org. Retrieved 2007-06-27.
  15. ^ Skoufas, George (July 2005). "Nesting and hatching success of the sea turtle Caretta caretta on Marathonissi island" (PDF). Belgian Journal of Zoology. 135 (2): 243–246. Retrieved 2009-01-02. {{cite journal}}: Cite has empty unknown parameter: |coauthors= (help)
  16. ^ "Conservation of the Akamas Peninsula (Cyprus)" (PDF), CONVENTION ON THE CONSERVATION OF EUROPEAN WILDLIFE AND NATURAL HABITATS, Strasbourg: Council of Europe, 29 November - 3 December-2004, retrieved 2009-01-02 {{citation}}: |format= requires |url= (help); Check date values in: |date= (help); Cite has empty unknown parameters: |coeditors= and |coauthors= (help)
  17. ^ a b 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)

References

  • 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.
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