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Loggerhead Turtles
By far, the most common sea turtle inhabiting our southeastern coastal waters is the loggerhead, Caretta caretta. Thousands of nesting females crawl ashore each year on the beaches of Florida, Georgia, and the Carolinas. The loggerhead is primarily a carnivore. Its diet includes crabs, shrimp, whelks, conches, fish, clams, jellyfish, sea urchins and even sponges. The loggerhead sea turtle is a large reddish-brown sea turtle with a disproportionately large head. Adult loggerheads range in size from 0.85-l.0 meters (33-40 inches) shell length and weigh between 68-182 kilograms (150-400 pounds). The largest shell size on record is 45 inches long. Loggerhead behavior patterns such as nighttime nesting and the production of large numbers of eggs are typical of sea turtles in general. Crawling from the surf after dark, the female selects a nest site above the reach of high tides. Some females make several "false crawls" before finding suitable nesting sites. Loggerheads have been seen pushing their noses to the sand while looking for a nesting place. It is not known what they are looking for -- perhaps a certain odor or moisture level in the sand.
The average number of eggs is about 120 but one nest under observation contained 198. The eggs have flexible shells and are the shape and approximate size of ping-pong balls. She completes the process by covering the nest first with her rear flippers then scattering sand with her front flippers. The nest appears to be an effective disguise to human eyes, but does not always deceive animal predators. Disguise and location alone do not insure a successful nest. Predators with a taste for turtle eggs include raccoons, ghost crabs, dogs, wild hogs and humans. Birds, commonly thought to be major predators, are little or no threat to the nest. Storm tides, rain and even plant roots can destroy the nest. Eggs that survive in the nest take approximately two months to hatch. It takes several days of concerted effort for the hatchlings to dig through the sand covering the egg chamber (Fig. 5). They almost always wait for the top layers of sand to cool before making their nighttime break for the sea. Emerging from the nest at night protects the hatchlings from most bird predators.
Biologists have long sought the nursery for the "missing year stage" of the loggerheads' life cycle. Fishermen from the Azores knew all along that they were drifting with ocean currents southward toward the trade-wind-driven westward currents above the equator for a free ride back "home." The "missing year" actually seems to be three or four years. This is when we first see them again off our eastern seaboard. Unfortunately, most of the juvenile sea turtles we see are dead, the victims of human activities and natural mortality. It takes many thousands of eggs to produce just one sexually mature adult. If a young female loggerhead survives all the hazards of her early pelagic life, she returns to the waters off nesting beaches. It is thought that loggerheads reach sexual maturity after twenty years of age. The males never return to shore but gather with the mature females to mate. Some scientists believe that loggerheads return to the beach of their birth for nesting, but this has never been proven. However, it is known that the Kemp's ridley does, due to the limited nesting sites of this species. The nesting time for sea turtles is usually on a two-or three- year cycle. They may nest five or more times, on a thirteen day rotation, in one season. Individual turtles may return to the same region to make their nests, but we don't know if they return to the same nesting beaches. Adult sea turtles have few natural enemies. Large sharks have been found with turtles and turtle parts in their stomachs, but man is the greatest enemy. The killing of adults and taking of eggs for food has all but stopped on our coast, but trawl fishing and habitat destruction take a great toll. Lights on beachfront buildings and parking lots have lured countless hatchlings to their deaths under the wheels of cars. Normally attracted to the brighter horizon of the open sea, the hatchling babies are confused by the artificial lighting. Hope does exist. The protection of nests from predators is ongoing in many areas. Some coastal communities are shading or turning off beachside lights during hatching season. Shrimpers are using Turtle Excluder Devices, or TED's. These devices have been shown to be effective in preventing net drowning of sea turtles.
Materials published by the National Oceanic and Atmospheric Administration (NOAA), and text from the Gray's Reef National Marine Sanctuary written by John A. Crawford were used to create this page about loggerhead turtles.
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After selecting her nest site the female excavates a "body pit." She creates this large depression using all four flippers, then begins digging alternately with her scoop-like rear flippers. This digging process continues for about 20 minutes and results in a light bulb-shaped hole 20 to 25 inches deep. When the mother turtle is satisfied with her nest cavity she places her rear flippers on each side of the narrow opening and lays eggs for about 20 minutes.
The odyssey of these young turtles will carry them well offshore. They apparently seek out rafts of the brown algae, Sargassum. Off our shores, that would put them in or near the Gulf Stream. Floating, and feeding on the myriad invertebrates living in the Sargassum, these young turtles probably ride around the fringes of the Sargasso Sea.