Sea turtles are large, air-breathing reptiles that inhabit tropical and subtropical seas throughout the world. Their streamlined bodies and large flippers make them remarkably adapted to life at sea. Sea turtles range in size from the smallest, Kemp's Ridley, measuring just 24 inches and weighing between 77 and 100 pounds, to the leatherback which can reach 4 to 8 feet in length and weigh from 650 to 2,000 pounds. Females must come ashore to lay their eggs in the sand; therefore, all sea turtles begin their lives as tiny hatchlings on land. Millions of sea turtles once roamed the earth's oceans, but now only a fraction remain.
Sea turtles are generally solitary creatures that remain submerged for much of the time they are at sea, which makes them extremely difficult to study. They rarely interact with one another outside of courtship and mating. When it is not nesting season, sea turtles may migrate hundreds, even thousands of miles. Sea turtles can sleep at the surface while in deep water or on the bottom wedged under rocks in near-shore waters. Many divers have seen green turtles sleeping under ledges in reefs and rocks. Hatchlings typically sleep floating on the surface with their front flippers folded back over the top of their backs.
Most females return faithfully to the same beach each time they are ready to nest. Not only do they appear on the same beach, they often emerge within a few hundred yards of where they last nested. To nest, the female turtle crawls to a dry part of the beach and begins to fling away loose sand with her flippers. She then constructs a “body pit” by digging with her flippers and rotating her body. After the body pit is complete, she digs an egg cavity using her cupped rear flippers as shovels. When the turtle has finished digging the egg chamber, she begins to lay eggs. Once all the eggs are in the chamber, the mother turtle uses her rear flippers to push sand over the top of the egg cavity. Gradually, she packs the sand down over the top and then begins using her front flippers to refill the body pit and disguise the nest. By throwing sand in all directions, it is much harder for predators to find the eggs. After the nest is thoroughly concealed, the female crawls back to the sea to rest before nesting again later that season or before beginning her migration back to her feeding ground. Once a female has left her nest, she never returns to tend it.
Incubation takes about 60 days, but since the temperature of the sand governs the speed at which the embryos develop, the hatching period can cover a broad range. Essentially, the hotter the sand surrounding the nest, the faster the embryos will develop. Cooler sand has a tendency to produce more males, with warmer sand producing a higher ratio of females. Unlike baby alligator, which are liberated from their nest by their mother, sea turtle hatchlings must do it all themselves. To break open their shells, hatchlings use a temporary, sharp egg-tooth, called caruncle. The caruncle is an extension of the upper jaw that falls off soon after birth. Digging out of the nest is a group effort that can take several days. Hatchlings usually emerge from their nest at night or during a rainstorm when temperatures are cooler.
Once they decide to burst out, they erupt from the nest cavity as a group. The little turtles orient themselves to the brightest horizon, and then dash toward the sea. If they don't make it to the ocean quickly, many hatchlings will die of dehydration in the sun or be caught by predators like birds and crabs. Once in the water, they typically swim several miles off shore, where they are caught in currents and seaweed that may carry them for years before returning to near-shore waters. There are many obstacles for hatchlings in the open ocean. Sharks, big fish, and circling birds all eat baby turtles, and they die after accidentally eating tar balls and plastic garbage. The obstacles are so numerous for baby turtles that it is guessed that
only about one in 1,000 survives to adulthood.
The ability of a sea turtle to migrate hundreds (and occasionally thousands) of miles from its feeding ground to its nesting beach is one of the most remarkable acts in the animal kingdom. The fact that adult females return faithfully to nest on the very beach where they were born makes this even more amazing.
There are eight living species of sea turtles; the loggerhead, green, black, hawksbill, kemp's ridley, olive ridley, flatback, and the leatherback. They do not have teeth, but their jaws have modified "beaks" suited to their particular diet. They do not have visible ears but have eardrums covered by skin. They hear best at low frequencies, and their sense of smell is excellent. Their vision underwater is good, but they are nearsighted out of water.
Sea turtles consume a variety of foods. The green sea turtle is a vegetarian, feeding mostly on sea grasses and algae, while the hawksbill feeds on sponges – consuming even the glass skeleton that protect the sponges. Crabs are a favorite food of the kemp's ridley while the giant leatherback eats mostly jellyfish and the loggerhead feed on a variety of shellfish, sponges, and jellyfish.
The natural obstacles faced by young and adult sea turtles are staggering, but it is the increasing threats caused by humans that are driving them to extinction. Today, all sea turtles found in U.S. waters are federally listed as endangered, except for the loggerhead which is listed as threatened. In nature, sea turtles face a host of life and death obstacles to their survival. Predators such as raccoons, crabs, and ants raid eggs and hatchlings still in the nest. Once they emerge, hatchlings make bite-sized meals for birds, crabs, and a host of predators in the ocean. Turtles are harvested for their meat, shells, and oil; habitat loss, fishing nets and long-line fishing hooks ensnare and drown thousands of turtles a year. Bright lights on beaches mislead nesting females and hatchlings, heading them in the wrong direction, causing them to die of dehydration or from auto accidents. Our ancient sea turtles need protection, as do all our creatures on land and in the sea. It is up to us to care for and protect their habitats so they can continue to survive, and hopefully, one day, flourish and fill the earth again.
For ocean theme
decorating and ocean
gifts, here are some sea turtle sculptures
and other beautiful
items that capture the grace, personality and detail of these amazing animals
you can find at our
online gift store:
Other fun turtle items: