Sea Turtles
A Green Story
Sea turtles are large, air-breathing reptiles that inhabit tropical and subtropical seas throughout the world. Their shells consist of an upper part (carapace) and a lower section (plastron). Hard scales (or scutes) cover all but the leatherback, and the number and arrangement of these scutes can be used to determine the species.
Sea turtles come in many different sizes, shapes and colors. The Olive Ridley is usually less than 100 pounds, while the leatherback typically ranges from 650 to 1,300 pounds! The upper shell, or carapace, of each sea turtle species ranges in length, color, shape and arrangement of scales.
Sea turtles 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. Their streamlined bodies and large flippers make them remarkably adapted to life at sea. However, sea turtles maintain close ties to land.
Research on marine turtles has uncovered many facts about these ancient creatures. Most of this research has been focused on nesting females and hatchlings emerging from the nest, largely because they are the easiest to find and study.
Thousands of sea turtles around the world have been tagged to help collect information about their growth rates, reproductive cycles and migration routes. After decades of studying sea turtles, much has been learned. However, many mysteries still remain.
Sea Turtles & Humans
Sea turtles have long fascinated people and have figured prominently in the mythology and folklore of many cultures. Off the eastern coast of Nicaragua, the story of a kind “Turtle Mother,” still lingers. Unfortunately, the spiritual significance of sea turtles has not saved them from being exploited for both food and for profit. Millions of sea turtles once roamed the earth’s oceans, but now only a fraction remain.
Reproduction
Only females come ashore to nest, returning to nest on the beach where they were born. Nesting seasons occur at different times around the world, with most females nesting at least twice if not more during each mating season. A female will not nest every year, typically skipping one or two years before returning.
Growth & Development
Researchers do not yet know how long baby turtles spend in the open sea or exactly where they go! It is thought that they spend their earliest, most vulnerable years floating around the sea in giant beds of sargasso weeds where they do little more than eat and grow. Once turtles reach dinner-plate size, they appear at feeding grounds in nearshore waters. They grow slowly and take between 15 and 50 years to reach reproductive maturity. There is no way to determine the age of a sea turtle from its physical appearance. It is theorized that some species can live over 100 years!
Status of the Species
Sea turtles once navigated throughout the world's oceans about 150 million years old. But in just the past 100 years, demand for turtle products has dwindled their populations. Destruction of feeding and nesting habitats and pollution of the world’s oceans are all taking a serious toll on remaining sea turtle populations. Many breeding populations have already become extinct. There could be a time in the near future when sea turtles are just an oddity found only in aquariums and natural history museums — unless action is taken today.
GREEN TRIVIA:
- The loggerhead sea turtle is listed as endangered or threatened in all of its habitats around the world.
- The most valuable of all reptiles, they are killed for their skins, calipee, meat and shells.
- Exploitation has already caused extinction of populations in many parts of the Caribbean.
- Loggerhead sea turtles make a migration of a few 1,000 km each way to reach nesting areas!
Lucky Is Very Lucky!
Lucky is a 325-pound loggerhead sea turtle. On the day she swam into the dolphin lagoon, she became very lucky! After staying on her own for over a week, she was observed with multiple flipper injuries, probably due to several shark attacks.
Though she is capable of swimming, her ability to avoid predators is severely diminished and she can no longer migrate up a beach to lay eggs. For these reasons, DE has adopted Lucky as a permanent member of our marine family. She has helped teach how incredible sea turtles are and how important it is that we protect them for the future, both theirs and ours!
Threats to Sea Turtle Survival
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.
Human-Caused Threats
In many cultures around the world, people still harvest sea turtles. Though most countries forbid the taking of eggs, eggs can often be found for sale in local markets. Adult sea turtles are harvested for their meat and souvenir products, such as jewelry made from hawksbill shells, also create a direct threat to sea turtles. Buying and selling turtle products within the U.S. is illegal, but turtle shell jewelry and souvenirs are the most frequent contraband seized by customs officials from tourists returning from the Caribbean.
Commercial Fishing
Each year, thousands of turtles become entangled in fishing nets and drown. At one time, as many as 55,000 sea turtles were killed each year in shrimp nets in the southeastern United States alone. Today, U.S. shrimpers are required to put Turtle Excluder Devices (TEDs) in their trawl nets. Unfortunately, not all fishermen comply with the law and sea turtles continue to drown in shrimp nets.
Ingestion of Debris and Plastic
Thousands of sea turtles die from eating or becoming entangled in non-degradable debris each year, including packing bands, balloons, pellets, bottles, vinyl films, tar balls, and styrofoam. Trash, particularly plastic bags thrown overboard from boats or dumped near beaches and swept out to sea, is eaten by turtles and becomes a deadly meal. Leatherbacks and loggerheads especially, are poor at distinguishing between floating jellyfish and floating plastic bags.
Artificial Lighting
Nesting turtles once had no trouble finding a quiet, dark beach on which to nest, but now they must compete with tourists, businesses and coastal residents for use of the beach. U.S. beaches are rapidly being lined with seaside condominiums, houses and hotels. Lights from these developments discourage females from nesting and cause hatchlings to become disoriented and wander inland, where they often die of dehydration or predation.
Coastal Armoring
Coastal armoring are structures that are installed in an attempt to protect beachfront property from erosion. These structures often block female turtles from reaching suitable nesting habitat and accelerate erosion down the beach. Armoring is especially problematic along the east coast of Florida, where sea turtles come to nest by the thousands.
Beach Nourishment
Beach nourishment consists of pumping, trucking or otherwise depositing sand on a beach to replace what has been lost to erosion. If the sand is too compacted for turtles to nest in or if the sand imported is drastically different from native beach sediments, this dramatically effects nest-site selection, digging behavior, incubation temperature and the moisture content of nests.
Pollution
When pollution kills aquatic plant and animal life, it also takes away the food sea turtles eat. Oil spills, urban runoff of chemicals, fertilizers and petroleum all contribute to water pollution. New research suggests that a disease now killing many sea turtles (fibropapillomas) may be linked to pollution in the oceans.
What should you do if you come upon a sea turtle nest?
Sometimes people encounter sea turtles on their own while walking on the beach at night during nesting season. If this happens to you, here are some simple rules to follow:
Sgt. Leatherback says, “Straighten up and pay attention! Lives depend on this!”
Do not walk on the beach with a flashlight or shine a light in the sea turtle's face. The light may cause the female to abort the nesting process, or other sea turtles nearby may be discouraged from nesting if there are lights on the beach.
Do not take pictures using flashes. This high-intensity light can be even more disturbing than the flashlights.
Stay clear and out of sight of the turtle until she begins laying eggs, otherwise you may scare her back into the sea.
For your safety, stay away from the turtle's head. Sea turtles, especially loggerheads, have very strong jaws and can harm you if provoked.
Do not handle the eggs or put any foreign objects into the nest. You can introduce bacteria or injure the eggs.
Do not handle or ride the sea turtle. In addition to being illegal, you may injure the turtle or cause her to leave without finishing nesting.
Do not disturb tracks left by turtles. Researchers sometimes use the tracks to identify the type of turtles that nested and to find and mark the nests.
