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Loggerhead sea turtle

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Loggerhead sea turtle
Australia-pacific-loggerhead-web-600x410.jpg
Scientific Classification
Scientific Name

Caretta caretta

The Loggerhead sea turtle is the largest hard shelled sea turtle in the world. Its shell is divided into two sections: carapace (upper shell) and plastron (underside). Males typically have longer tails and claws than the females. Scientists believe that Loggerheads are long lived and could live, over 50 years. Because of coastal lighting and housing developments, human disturbances, the turtles have suffered severe habitat loss.

Body Design

The underside of a Loggerhead

The Loggerhead sea turtle is the largest hard shelled turtle in the world. Adults have an average weight range of 180 to 440 lb, and their length averages from 28 to 37 in. The heaviest Loggerhead to date is 1202 Lb., with its carapace of 84 in. The head and carapace ranges from a yellow-orange to a reddish brown, while the underside is typically a pale yellow. The turtle's neck and sides are brown on the tops and yellow on the sides and bottom. [2]

The turtle's shell is divided into two sections, carapace and plastron. The carapace is further divided into large plates. Typically, 11-12 pairs of small plates on rim of the carapace. Five vertebral plates run down the carapace's mid line, while five pairs of costal plates border them. The neck plate is located at the base of the head. The carapace connects to the underside by three pairs of lower plates forming the bridge of the shell. The underside features paired throat, humeral, pectoral, abdominal, femoral, and anal plates. The shell serves as external armor, but loggerhead sea turtles cannot retract their heads or flippers into their shells.[3]

Males typically have longer tails and claws than the females. Also the males have shorter neck pads than females, and the carapaces of males are wider and less domed than the females' and males typically have wider heads than females. You can't tell the sex of juveniles by their appearance only through dissection, laparoscopy (an operation performed on the abdomen), and histological examination (cell anatomy). Lachrymal glands located behind each eye allow the loggerhead to maintain balance by eliminating the excess salt obtained from ingesting ocean water. On land, the excretion of excess salt gives the false impression that the turtle is crying.[4]

Life Cycle

Life cycle of a Loggerhead

Scientists believe that loggerheads are long lived and could live to 50 years or more. laying an average of 4 clutches containing roughly 100 – 120 eggs in each. Hatchlings range in color from light brown to almost black, lacking the adult's distinct yellows and reds. When hatching, they measure about 1.8 in and weigh about 20 g. Female loggerheads reach maturity at about 35 years of age. When the eggs hatch the turtles make their way to the surface in a group, then, (usually at night) they head toward the sea across the beach. They go at night in response to cooler temperatures of the sand. They head toward the ocean, attracted by the light reflected off the sand. Lights on the beach or along the shore can confuse the baby loggerhead and lead them in the wrong direction. Hatching is the time that they are in great danger to predators which have a knack of knowing when the turtles will hatch. The hatchlings must travel across the beach on their own. Loggerhead turtles are under threat from the moment they hatch. The trip from the nest to the water in the ocean is dangerous for the hatchlings, with birds, crabs, and fish all trying to eat them.[5]

Because of coastal lighting and housing developments, human disturbances, the loss of nesting habitat has been the greatest threat, which causes losses during the emergence of hatchlings. Other major threats include not as known capture in longline fishing, shrimp trawling and pollution. Incidental capture in fisheries played an important part in the recent population decline observed for the loggerhead sea turtle. [6]

Ecology

Range of where loggerheads live

The loggerhead sea turtle is omnivorous, feeding mainly on bottom-dwelling invertebrates, such as gastropods, bivalves, and decapods. It has the most known prey than any other sea turtle. Other food items include sponges, corals, sea pens, polychaete worms, sea anemones, cephalopods, barnacles, brachiopods, isopods, insects, bryozoans, sea urchins, sand dollars, sea cucumbers, starfish, fish (eggs, juveniles, and adults), hatchling turtles (including members of its own species), algae, and vascular plants.[7]During migration through the open sea, loggerheads eat jellyfish, floating molluscs, floating egg clusters, squid, and flying fish. Loggerheads crush prey with their large and powerful jaws. Projecting scale points on the front margin of the front limbs allow manipulation of the food. These points can be used as "pseudo-claws" to tear large pieces of food in the loggerhead's mouth. The loggerhead will turn its neck sideways to consume the torn food. The digestion rate in loggerheads is temperature-dependent; it increases as temperature increases.[8]

Loggerheads have numerous predators, especially early in their lives. Egg and nestling predators include ghost crabs, oligochaete worms, and beetles. During their migration from their nests to the sea, hatchlings are preyed on by dipteran larvae, crabs, toads, lizards, snakes, seabirds. In the ocean, predators of the loggerhead juveniles include fish, such as parrotfish and moray eels, and portunid crabs. Adults are more rarely attacked due to their large size, but may be preyed on by large sharks, seals, and killer whales. Nesting females are attacked by flesh flies, feral dogs, and humans. Salt marsh mosquitoes can also annoy nesting females.[9]

Threatened

Nearly 24,000 metric tons of plastic are dumped into the ocean each year. Turtles ingest a wide variety of the floating debris, including bags, sheets, pellets, balloons and abandoned fishing line. Loggerheads may mistake the floating plastic for jellyfish, a common food item. The ingested plastic causes numerous health concerns, including intestinal blockage, reduced nutrient absorption and malnutrition, suffocation, or starvation. Ingested plastics release toxic compounds which may accumulate in internal tissues. Such toxins may lead to a thinning of eggshells, tissue damage, or departure from natural behaviors.[10]

References

  1. Patterson, G.K., Daugherty, C.H. Caretta_caretta Wikispecies. Web. January 10, 2017.
  2. Loggerhead Turtle (Caretta caretta) Webcitation. Web. January 1, 2017. Author unknown.
  3. Hermann Ehlers Marine Turtles Africa Webcitation. Web. October 21, 2004.
  4. C. L. YNTEMA and N. MROSOVS. Critical periods and pivotal temperatures for sexual differentiation in loggerhead sea turtles Webcitation. Web. September 29,1981.
  5. The lifecycle of Loggerheads Kiawah Turtles. Web. March 14, 2015. Author unknown.
  6. Loggerhead Sea Turtle Seaturtles 911 May 13, 2009. Author Unknown.
  7. MICHAEL C. JAMES, KATHLEEN MARTIN, and PETER H. DUTTON. [1] Martin Duton. January 31 2009
  8. René Márquez M. [2] Márquez, R..January 16, 2017(last-accessed)
  9. Sam D. Recovery Plan for U.S. Pacific Populations of the Loggerhead Turtle (Caretta caretta) Pacific Sea Turtle Recovery Team. January 18,2017 (last-accessed)
  10. Ridely Kem Decline of the Sea Turtles: Causes and Prevention Commission on Life Sciences. April 17, 2010 (last-modified)