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loggerhead turtle

 
Dictionary: loggerhead turtle

n.
A very large marine turtle (Caretta caretta) inhabiting warm ocean waters and having a large beaked head.


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Animal Encyclopedia: Loggerhead turtle
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Caretta caretta

TAXONOMY

Testudo caretta Linnaeus, 1758, Insulas Americanas ("American islands"). No subspecies are currently recognized, although the Pacific and Atlantic populations have been considered different races by some authors.

OTHER COMMON NAMES

English: Loggerhead; French: Caouanne; German: Unechte Karettschildkröte; Spanish: Caguama, tortuga boba.

PHYSICAL CHARACTERISTICS

The loggerhead seaturtle is the largest species in this family, reaching 84 in (213 cm) carapace length and weights up to 1,000 lb (454 kg). The head is quite broad posteriorly and short and round in front, hence the common name. Two pairs of prefrontal scales are present on the top of the head forward of the eyes. The heart-shaped carapace is serrate posteriorly and has five or more pairs of pleural scutes, the first pair in contact with the nuchal scute. Eleven to 15 (typically 12 or 13) marginal scutes are present on the rim of the shell. Three inframarginal scutes (all lacking pores) are present on the bridge between the marginal and the plastral scutes.

DISTRIBUTION

All tropical and temperate seas but rare in the eastern and central Pacific Ocean.

HABITAT

Mainly shallow marine waters along tropical continental shores but also around some islands. Loggerhead turtles enter bays, creeks, salt marshes, and the mouths of rivers.

BEHAVIOR

Loggerhead turtles undertake long migrations, often using warm oceanic currents for dispersal. A juvenile released off Okinawa Island was recaptured off San Diego just over two years later, and several adults have been recaptured 1,300–1,700 mi (2,100–2,700 km) from the site of original capture. Females migrate to nesting areas every two or three years. Adults often aggregate off nesting beaches before migrating

back to feeding habitats. Hatchlings and small juveniles are apparently pelagic and associated with floating plants, animals, and flotsam. This species often ventures into temperate waters and nests farther north than any other seaturtle (solitary nests have been found in New Jersey in the United States). When in open waters, loggerhead seaturtles often float on the surface, presumably sleeping. Mitochondrial DNA studies have shown that turtles from different nesting regions differ genetically. This finding suggests that females return to the nesting beaches on which they hatched.

FEEDING ECOLOGY AND DIET

The loggerhead turtle is primarily carnivorous throughout its life. Hatchlings are known to eat jellyfish, snails, crustaceans, insects, and sargassum (an alga), most obtained while the turtle is floating in sargassum mats. Juveniles and adults feed mostly on the bottom and eat sponges, worms, conch and other snails, clams, squid, octopus, barnacles, horseshoe and other crabs, shrimp, sea urchins, fish, and occasionally hatchling seaturtles, algae, and other aquatic plants.

REPRODUCTIVE BIOLOGY

Loggerhead turtles reach maturity between 10 and 30 years of age. Courtship and mating apparently occur most commonly during the migrations to nesting grounds, several weeks before nesting begins, rather than near the nesting beaches. The male circles the female, bites her neck and shoulders, and mounts her shell from behind. The pair typically floats at the surface during copulation. Mating can occur day or night. Females apparently mate several times. DNA studies have revealed that more than one male may father eggs laid in a single clutch. Nesting usually occurs in spring and summer but with great geographic variation, particularly latitudinal, in timing and duration.

Nests are generally excavated above the high tide line, in front of the first dune, and usually at night. Once the site is chosen, the female first excavates a body pit using all four limbs and then uses only her rear feet to dig the nest chamber in the bottom of the pit. She then deposits 23–198 spherical, leathery eggs (usually 95–130) that measure 1–2 in (2.5–5.1 cm) in diameter and 1–2 oz (26–47 g) in mass. She then covers the nest, first using only her hind legs and eventually using all four limbs to cover and camouflage the entire site. Females may lay up to seven clutches per season at intervals of nine to 28 days, most typically about every two weeks, although four or five clutches per season is more usual. Most females nest only every two or three years. Incubation requires 46–80 days, typically 60–65, depending on the temperature. Hatchlings generally emerge from nests at night to avoid lethal ground temperatures during the day. They then scurry immediately to the surf. This species has temperature-dependent sex determination. Mostly females are produced above 84–86°F (29–30°C), and mostly males are produced below this temperature.

CONSERVATION STATUS

Loggerhead turtles are classified as Endangered on the IUCN Red List.

SIGNIFICANCE TO HUMANS

Although direct consumption of adults and eggs may be declining in many areas, humans are still responsible for much indirect mortality among loggerhead seaturtles through activity on or development of nesting beaches, by contributing to increases in predators such as raccoons and dogs, by drowning the turtles in shrimp or fish nets, and with pollutants.

WordNet: loggerhead turtle
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Note: click on a word meaning below to see its connections and related words.

The noun has one meaning:

Meaning #1: very large carnivorous sea turtle; wide ranging in warm open seas
  Synonyms: loggerhead, Caretta caretta


Wikipedia: Loggerhead Sea Turtle
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Loggerhead Sea Turtle
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Subclass: Anapsida
Order: Testudines
Family: Cheloniidae
Genus: Caretta
Rafinesque, 1814
Species: C. caretta
Binomial name
Caretta caretta
Linnaeus, 1758

The Loggerhead Sea Turtle (Caretta caretta) is a sea turtle and the only member of the genus Caretta. The genus name "Caretta" is a latinization of the French "caret", meaning turtle, tortoise, or sea turtle.[1] A loggerhead sea turtle reportedly grows up to 800 lbs (364 kg) and 3.5 feet (1.1 m) long.[2] Their shell color is a reddish brown color, and the color of their skin is brown yellow. They are named for their disproportionately large head. They are also the state reptile of South Carolina.[3]

Contents

Trophic ecology

The species feeds on molluscs, crustaceans, fish, jellyfish, crabs, shrimp and Portuguese Man o' War and other small to medium-sized marine animals, which they crush with their large and powerful jaws. As with other sea turtles, females return to lay their eggs on or near the same beach where they hatched. Unlike other sea turtles, courtship and mating usually do not take place near the nesting beach but rather along the migration routes between feeding and breeding grounds.

Scientists in Hawaii use satellite transponders to track loggerhead sea turtles in the Northern Pacific Ocean.[4].

Life history

Baby Loggerhead Sea Turtle.

In the Mediterranean, Loggerheads mate from late March to early June. The female nesting season is at its peak in June and July, but this depends on the nesting beach. The clutch may vary from 70 to 150 eggs. Each egg is roughly the size and shape of a ping-pong ball. The average interval between nesting seasons is two to three years.

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; with the largest concentration of nests in south Florida. Statistics collected in Florida since 1998 however indicate the lowest nesting levels Florida has seen in 17 years, where nesting rates have declined from 85,988 nests in 1998 to approximately 45,084 in 2007.[5]

After approximately 60 days, the hatchlings emerge usually at night when protection from predation is greater. Because they usually follow the brightest light to the ocean's edge, artificial lights from human activity can lead them astray. Once in the ocean they use ocean currents to travel to the Sargasso Sea using the Sargassum as protection until they mature.[6]

An alternative to migration for many loggerheads is hibernation to varying degrees as the water cools. By February they are submerged for up to seven hours at a time, emerging for only seven minutes to recover. Although outdone by freshwater turtles, these are the longest recorded dives for any air-breathing marine vertebrate[7].

Most loggerheads that reach adulthood live for longer than 30 years, and can often live past 50 years. They are immune to the toxins of a Portuguese Man o' War as the turtles have often been seen feeding on them.[citation needed]

Etymology and taxonomic history

Two subspecies are recognized: Caretta caretta gigas, is found in 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 Peloponese and in Dalyan in southwestern Turkey. (see article; June Haimoff).

Feeding

A loggerhead mainly feeds on bottom dwelling invertebrates. They eat horseshoe crabs, clams, mussels, and other invertebrates. Their powerful jaw muscles help them to easily crush the shellfish. During migration through the open sea, loggerheads eat jellyfishes, floating mollusks, floating egg clusters, squids and flying fishes.

Importance to humans

Loggerhead Sea Turtles were once intensively hunted for their meat and eggs, along with their fat which was used in cosmetics and medication. The Loggerhead Sea Turtles were also killed for their shells, which are used to make items such as combs. As a result, both subspecies are now internationally protected.

Conservation

Loggerhead Sea Turtle escapes from fishing net through a TED (Turtle Excluder Device).

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 Services and National Marine Fisheries Service classify them as a threatened species under the Endangered Species Act.

Today the main threat to the adult loggerheads lies in shrimp trawls and crab fishing nets, to which many loggerheads annually fall victim[8]. Furthermore, adults are often injured by speedboat propellers and by swallowing fishing hooks or getting caught in nets. Internationally, animal protection organizations take pains to monitor and protect the turtles' nesting grounds in Turkey,[9] Greece[10], Bonaire, and Costa Rica. The turtles can also be found around the Italian islands of Lampedusa and Linosa, off the coast of Sicily, and in Calabria, where it is particularly endangered. Furthermore, the turtles are known to nest on the beaches of Cyprus, especially Akamas and Alagadi Beach.[11]

Loggerhead Sea Turtle nest roped off as part of the Sea Turtle Protection Project on Hilton Head Island

In many places during the nesting season, workers search the coastline to find evidence of nests. Once found, a nest will be uncovered and the eggs carefully counted, if the nest is dangerously located the eggs will be moved to a better spot. Plastic fencing will be placed at or near the surface to protect the eggs from large predators such as raccoons or even dogs. The barrier used is large enough to allow the hatchlings to emerge without difficulty. The nests are checked daily for disturbances; several days after there is indication that the eggs have hatched the nest will be uncovered and the tally of hatched eggs, undeveloped eggs, and dead hatchlings will be recorded. If any hatchlings are found, they are either taken to be raised and released, or taken to research facilities. Ones that appear strong and healthy may instead be 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 require the travel from their nest to the ocean in order to build up strength for the journey ahead, so interfering by helping it to the ocean actually lowers their chances of survival.[citation needed] The Fripp Island, SC Turtle Patrol each year sets pieces of drift wood from the nests toward the sea as guides so the hatchlings get to start out in the right direction. Loggerheads are listed as Endangered under both Australia's Environment Protection and Biodiversity Conservation Act 1999 and Queensland's Nature Conservation Act 1992.

Habitat

The loggerhead sea turtle lives in areas such as bays, lagoons, salt marshes, creeks, ship channels, and the mouths of large rivers. Coral reefs, rocky places, and ship wrecks are places where you might find a feeding ground for loggerheads. Loggerheads nest on ocean beaches and on estuarine shorelines with suitable sand. They like to feed in coastal bays and estuaries, as well as in the shallow water along the Atlantic, Pacific and Indian Oceans.

See also

References

  1. ^ http:www.widecast.org/sea/definitions.cfm[dead link]
  2. ^ <http://www.fws.gov/blackbeardisland/loggerhead.htm>
  3. ^ <http://www.enchantedlearning.com/usa/states/southcarolina/>
  4. ^ Dennis Hollier (August/September 2008). "Mapping the Void". Hana Hou!, Vol. 11, No. 4. http://www.hanahou.com/pages/Magazine.asp?Action=DrawArticle&ArticleID=704&MagazineID=44. 
  5. ^ [1][dead link]
  6. ^ BBC NEWS | Science/Nature | Turtles return home after UK stay
  7. ^ Hochscheid, S., F. Bentivegna & G.C. Hays. (2005) "First records of dive durations for a hibernating sea turtle." Biol. Lett. 1(1): 82-6.
  8. ^ http://community.oceana.org/creatures/loggerhead-turtle
  9. ^ "Loggerhead Turtles in the Dalyan River, Mulğa Province, Turkey, 2004". seaturtle.org. http://www.seaturtle.org/mtn/archives/mtn108/mtn108p14.shtml. Retrieved 2007-06-27. 
  10. ^ 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.. http://www.naturalsciences.be/institute/associations/rbzs_website/bjz/back/pdf/BJZ%20135(2)/Volume%20135(2),%20pp.%20243-246.pdf. Retrieved 2009-01-02. 
  11. ^ "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, http://www.coe.int/t/dg4/cultureheritage/conventions/Bern/T-PVS/sc24_files15_en.pdf, retrieved 2009-01-02 

Bibliography

External links


 
 

 

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Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.  Read more
Animal Encyclopedia. Grzimek's Animal Life Encyclopedia. Copyright © 2005 by The Gale Group, Inc. All rights reserved.  Read more
WordNet. WordNet 1.7.1 Copyright © 2001 by Princeton University. All rights reserved.  Read more
Wikipedia. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article "Loggerhead Sea Turtle" Read more