Sea turtles are a fundamental link in marine ecosystems. They help maintain the health of seagrass beds and coral reefs that benefit commercially valuable species such as shrimp, lobster, and tuna. Sea turtles are the live representatives of a group of reptiles that have existed on Earth and traveled our seas for the last 100 million years. Turtles have major cultural significance and tourism value. Five of the seven species are found around the world, mainly in tropical and subtropical waters. The remaining two species, though, have relatively restricted ranges: Kemp’s ridley is found mainly in the Gulf of Mexico and the flatback turtle around northern Australia and southern Papua New Guinea.
Many sea turtle species can be found in Florida. A few of the most common are noted below:
LOGGERHEAD
The most common sea turtle in Florida, the loggerhead is named for its massive, block-like head. Loggerheads are among the larger sea turtles; adults weigh an average of 275 pounds and have a shell length of about 3 feet. Its carapace, which is a ruddy brown on top and creamy yellow underneath, is very broad near the front of the turtle and tapers toward the rear. Each of its flippers has two claws. As is true for all sea turtles, the adult male has a long tail, whereas the female’s tail is short; however, a juvenile’s cannot be determined externally.
The powerful jaws of the loggerhead allow it to easily crush the clams, crabs, and other armored animals it eats. A slow swimmer compared to other sea turtles, the loggerhead occasionally falls prey to sharks, and individuals missing flippers or chunks of their shell are not an uncommon sight. However, the loggerhead compensates for its lack of speed with stamina; for example, a loggerhead that had been tagged at Melbourne Beach was captured off the coast of Cuba 11 days later.
GREEN TURTLE
Green turtles, named for their green body fat, were valued by European settlers in the New World for their meat, hide, eggs, and “calipee” (the fat attached to the lower shell that formed the basis of the popular green turtle soup). Merchants learned that the turtles could be kept alive by turning them on their backs in a shaded area. This discovery made it possible to ship fresh turtles to overseas markets. By 1878, 15,000 green turtles a year were shipped from Florida and the Caribbean to England. At one time, Key West was a major processing center for the trade. The turtles were kept in water-filled pens known as “kraals,” or corrals. These corrals now serve a more benign role as a tourist attraction.
A more streamlined-looking turtle than the bulky loggerhead, the green turtle weighs an average of 350 pounds and has a small head for its body size. Its oval-shaped upper shell averages 3.3 feet in length and is olive-brown with darker streaks running through it; its lower shell, or plastron, is yellow.
Green turtles are found during the day in shallow flats and seagrass meadows and return every evening to their usual sleeping quarters-scattered rock ledges, oyster bars, and coral reefs. Adult green turtles are unique among sea turtles in that they are largely vegetarians, consuming primarily seagrasses and algae. Approximately 100 to 1,000 green turtles nest on Florida’s beaches each year from June through late September.
HAWKSBILL
The hawksbill is a small, agile turtle whose beautiful tortoise-colored shell is its greatest liability. The shell is still used in some European and Asian countries to make jewelry, hair decorations and other ornaments, even though international trade in hawksbill products has been banned in much of the world.
Hawksbills weigh from 100 to 200 pounds as adults and are approximately 30 inches in shell length. Its carapace is shaded with black and brown markings on a background of amber. The shields of this kaleidoscopic armor overlap, and the rear of the carapace is serrated. Its body is oval-shaped, its head is narrow, and its raptor-like jaws give the hawksbill its name. These jaws are perfectly adapted for collecting its preferred food, sponges. Although sponges are composed of tiny glasslike needles, this potentially dangerous diet apparently causes the turtle no harm.
Hawksbills are the most tropical of the sea turtles and are usually found in lagoons, reefs, bays, and estuaries of the Atlantic, Pacific, and Indian oceans. They are frequently spotted by divers off the Florida Keys, and a few nests are documented annually from the Keys to Canaveral National Seashore.