Sea turtles are large, air-breathing reptiles that inhabit tropical and subtropical seas throughout the world. Having inhabited the earth for some 100 million years, sea turtles are known as living fossils.
Sea turtles are adapted very well for life in the sea. Their paddle-shaped flippers, the position of the eyelids, and their streamlined body shape are all adaptations to the aquatic environment. Other important adaptations include the capacity to excrete the excess salt ingested with seawater and food, and the ability to dive and stay submerged for up to 20 or 30 minutes. Sea turtles do not have visible ears; internal eardrums are covered by skin. They hear best at low frequencies, and their sense of smell is excellent. They also have good sight underwater. Sea turtles have a bony shell, called a carapace, covering their body, which protects them from predators.
Sea turtles are different from tortoises, although they look similar at first sight. The most distinctive characteristic of sea turtles is that they do not pull the head and legs into the carapace when threatened.
Sea turtles are adapted very well for life in the sea. Their paddle-shaped flippers, the position of the eyelids, and their streamlined body shape are all adaptations to the aquatic environment. Other important adaptations include the capacity to excrete the excess salt ingested with seawater and food, and the ability to dive and stay submerged for up to 20 or 30 minutes.
Sea Turtles Species
There are seven species of sea turtles, six of which are found in Indonesian waters. These six species are:
The green turtle (Chelonia mydas)
- The hawksbill turtle (Eretmochelys imbricata)
- The loggerhead turtle (Caretta caretta)
- The olive ridley turtle (Lepidochelys olivacea)
- The leatherback turtle (Dermochelys coriacea)
- The flatback turtle (Natator depressus)
The most abundant species in Indonesia is the green turtle, which is widely distributed throughout the Indonesian archipelago.
Sea turtles can take between 15 to 50 years to sexually mature, depending on the species and the geographic location. During mating season males may court a female by nuzzling her head or by gently biting the back of her neck and rear flippers. The male then clings to the back of the female's shell and folds his long tail under her shell to copulate. Sometimes several males will compete for females and may even fight each other.
Only females come ashore to nest; males rarely return to land after crawling into the sea as hatchlings. Most females return to nest on the beach where they were born (natal beach). They dig an egg chamber, which they fill with about 100 eggs (sometimes more), and then gently cover the eggs with sand and spread sand over a wide area with their front flippers to obscure the exact location of the egg chamber. After this tiring process, which may take between one and three hours, female turtles return to the sea.
Sea turtles are generally slow and awkward on land, and nesting is an exhausting work. Nesting sea turtles appear to shed tears, but the turtle is just secreting salt that accumulates in her body. Some turtles will abort the nesting process if they are harassed or feel they are in danger. For this reason it is important that sea turtles are never disturbed during the nesting and egg-laying process.
Threats to Sea Turtles
Sea turtles have suffered dramatic population declines in recent decades. Many populations face extinction in the near future. Natural hazard, as well as anthropogenic ones threaten sea turtles from the moment of their birth. Predators such as wild pigs, crabs, birds and monitor lizards feed on newly hatched turtles. However, in Indonesia, as in the rest of the world, humans have become the biggest threat to turtle survival. Over-developed coastal areas have reduced natural nesting habitats. Capture of adult turtles for meat, leather and shell products has decreased breeding populations. In many cultures around the world people still harvest sea turtle eggs for consumption. Green turtles and their eggs are actually one of the most overexploited natural resources in Indonesia. Bali is a very big consumer of turtle meat, and turtle meat is used in religious ceremonies. More than 10, 000 turtles per year are killed for the Bali market.
All sea turtles have been listed in Appendix I of the Convention on International Trade in Endangered Species (CITES). This Convention strictly prohibits all international trade in sea turtles and their products. To help protect sea turtles remember the following:
- Do not buy or consume any food derived from sea turtles (eggs or meat).
- Do not buy or wear any fashionable material made from sea turtle shells.
- Never throw plastic garbage or any dangerous materials into the sea. Some turtles mistake plastic for their food (jellyfish), resulting in illness or death.
- Never harass nesting turtles since they may abort the nesting process. Keep your distance, or better still, leave altogether!
- Do not harvest turtle eggs. This practice will eventually result in no new turtles being born, hence no more turtles, no more eggs and no possibility for sustainable income-generation activities.
- Keep the coral reefs healthy. Intact coral reefs are an important feeding and resting habitat for sea turtles.
- Support sea turtle conservation programs.
- Research and Management Techniques for Conservation of Sea Turtles, edited by Karen L. Eckert, IUCN/SSC Marine Turtle Specialist Group, 1999