Wednesday, 14 April 2010

Wednesday, 24th March 2010 - Loggerhead Sea Turtle

The loggerhead sea turtle (Caretta caretta) is the world's most-studied and well-known sea-turtle. It is the only member of the genus Caretta. The genus name "Caretta" is a latinization of the French "caret", meaning turtle, tortoise, or sea turtle. Adult loggerhead sea turtles weigh from 170 to 350 pounds (77 to 160 kg) and measure 31 to 45 inches (79 to 110 cm). Their shell is a reddish brown color, and their skin ranges from yellow to brown. The name loggerhead comes from their disproportionately large head. The loggerhead sea turtle also holds the title of the world's largest hard-shelled turtle.

Early life
The loggerhead's sex is determined during incubation. Incubation temperatures generally range from 79–90 °F (26–32 °C). Eggs which are incubated at the lower range of temperatures yield males while eggs incubated at higher temperatures result in females. After incubating for approximately 80 days, hatchlings emerge from the eggs and dig their way to the surface of the beach. This usually occurs at night when predation is reduced. Hatchlings head for the water, aided by the reflection of the moon off the ocean. A loggerhead hatchling averages about 1.8 inches (4.6 cm) in length and weighs around 20 grams (0.71 oz).

Breeding
The loggerhead mating period may last up to six weeks. It appears that these turtles court their mates, however these behaviors have not been thoroughly examined. Nuzzling, biting, head movements, and flipper movements are 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. Over several months, females produces many 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. The nesting area must be selected carefully because it will have an affect on characteristics of the turtle such as fitness, emergence ratio, and vulnerability to nest predators. Clutch size ranges from 7–15 centimetres (70–150 mm). Each egg is roughly the size and shape of a ping-pong ball.

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 or no light pollution. The largest concentration of nesting is in south Florida.








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