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Sea turtles are reptiles whose ancestors evolved on land and returned to the sea to live about 150 million years ago. They are one of the few species so ancient that they watched the dinosaurs evolve and become extinct. The biological classification of the sea turtle is listed below:
As reptiles, sea turtles possess the following traits:
- They are cold-blooded, meaning that they get their body heat from the environment rather than making their own.
- They breathe air
- Their skin has scales
In addition to these reptilian traits, all species of turtles have evolved a bony outer shell which protects them from predators, as turtles are not known for their speed. The shell covers both the dorsal (back) and ventral (belly) surfaces and is considered the most highly developed protective armor of any vertebrate species to have ever lived. The dorsal portion of the shell is known as the carapace and is covered with large scale-like structures called scutes. The ventral portion of the shell is known as the plastron. The carapace and plastron are connected at the sides by hard-shelled plates known as lateral bridges. Openings exist between the carapace and plastron for the head, tail, and limbs. While most species of land turtles and tortoises are able to retract their heads into their shells for added protection, sea turtles are not able to do so, and their heads remain out at all times.
The sea turtle's body is wonderfully adapted to life in the ocean. Their shells are lighter and more streamlined than those of their terrestrial counterparts, and their front and rear limbs have evolved into flippers making them efficient and graceful swimmers, capable of swimming long distances in a relatively short period of time. Sea turtles have been known to move through the water as fast as 35 mph. When active, sea turtles swim to the surface every few minutes in order to breathe. When sleeping or resting, which usually occurs at night, adult sea turtles can remain underwater for more than 2 hours without breathing. This is due to the fact that turtles are capable of containing higher concentrations of carbon dioxide in their blood than most other air-breathing animals, enabling them to use their oxygen very efficiently. Both muscles and blood are able to store oxygen in large quantities, allowing sea turtles to remain underwater for such long periods of time. Juvenile sea turtles have not developed this ability as well as adults and must sleep afloat at the water's surface.
In addition to solving the problems of swimming and breathing, sea turtles have also come up with an ingenious way to rid their bodies of the salts they accumulate from the seawater in which they live. Just behind each eye is a salt gland. The salt glands help sea turtles to maintain a healthy water balance by shedding large "tears" of excess salt. If a sea turtle appears to be "crying" it is usually not cause for alarm, as the turtles are merely keeping their physiology in check. It is not because they are upset or sad.
Four of the seven existing species of sea turtles can be found in Hawaiian waters. They are the green sea turtle, the hawksbill, the leatherback and the olive ridley. Of these, by far the most common is the green sea turtle, or honu (pronounced hoe'-new), as it is known in Hawaiian.
Listed as a threatened species and protected in Hawaii under state law, the federal Endangered Species Act, and listed under the Convention on International Trade of Endangered Species (CITES), making it illegal to import or export turtle products. It is illegal to kill, capture, or harass sea turtles. All six species of sea turtles in the U.S. are protected under the Endangered Species Act of 1973 . Through interagency coordination under Section 7 of the ESA, sea turtles are protected by ensuring that Federal actions will not jeopardize the continued existence of the species. Successful consultations have been conducted with the Minerals Management Service for oil and gas activities, the U.S. Army Corps of Engineers for dredging activities, the U.S. Navy for explosives testing, the Environmental Protection Agency for the designation of dredged material disposal sites, and many other Federal agencies for activities ranging from nuclear power plant construction to scientific research. One of the most important ways NMFS acts to protect sea turtles is through requiring trawl fishermen to use Turtle Excluder Devices while fishing. Recovery plans have been finalized for all of the sea turtles found in US waters. These plans are available for review at our recovery plan page.
Factors affecting Sea Turtle Populations:
There were once several million sea turtles worldwide. Today, fewer than 200,000 nesting females are thought to remain. In Hawaii, scientists currently estimate that only 100 to 350 females nest each year, predominantly at French Frigate Shoals in the Northwest Hawaiian chain. Listed below are some of the factors believed to have contributed to the decline of the sea turtle, as well as other sea turtle species:
Sea turtles have long been hunted for a variety of uses. Their shells have been used to make jewelry and ornaments, their skin to make small leather goods, their meat and eggs for food, and their fat for oil. In modern times, the number of sea turtles taken has increased dramatically due to the opportunity for profits they provide through commercial trade.
Ancient Hawaiians used the meat of the sea turtle for food. Sea turtles are also recognized as being the main ingredient in turtle soup. Before protective laws such as the Federal Endangered Species Act of 1973 were passed, sea turtles were killed in large numbers to feed fishing crews in the Northwestern Hawaiian Islands and to provide meat for restaurants. Hawaiian populations experienced dramatic declines as a result. Because sea turtles take so many years to reach sexual maturity, it has taken 20 years since the passing of the Endangered species Act to see evidence of a population recovery.
Their natural habits also make sea turtles vulnerable to hunters. Because they lay their eggs in such a predictable way and are defenseless on land, poachers continue to kill hundreds of sea turtles each year for their eggs, shells and meat, despite laws prohibiting these activities in many countries. Egg clutches are especially easy to spot. After laying her eggs, the female turtle must struggle back to the ocean leaving a "tell-tale" trail behind in the sand.
Some native Pacific Islanders, as well as groups of native peoples in other parts of the world, continue to hunt depleted sea turtle populations for food. Continued subsistence takes under such conditions seriously risk both the survival of the species and the availability of this food source in the future.
Effects of Some Fisheries
Another important cause of sea turtle death is incidental (or non-deliberate) catch in fishing gear. Commercial Brine Shrimp fishers use nets that trap and drown more than 10,000 sea turtles each year. Many sea turtles could be saved if the shrimpers would use devices, called turtle excluder devices (TEDS), that keep turtles out of the nets. Laws exist that require shrimpers to install and use such devices, yet many shrimpers do not abide by them. In addition, thousands of sea turtles become entangled in longlines, driftnets, coastal gill nets and other discarded fishing gear each year.
Litter and other marine debris can prove deadly to sea turtles when they entangle the turtles or are mistaken for food and ingested. Plastics are particularly harmful as they are not easily digested and remain in the turtle's stomachs for long periods of time, releasing toxic substances. Ingested plastics also can clog the turtle's digestive system. blocking the proper passage of food. Thus, sea turtles may actually starve from ingesting plastic debris. Balls of oil and tar have also been found in the throats and stomachs of deceased sea turtles indicating that oil spills may pose another cause for concern.
Coastal Development and Habitat Degradation
Sea turtle nesting beaches are lost each year to coastal development, leaving the females without a familiar place to lay their eggs. Noise, lights and beach obstructions are disruptive to nesting areas and threaten this critical part of the sea turtle's life cycle. Some turtles may chose to nest on less developed beaches nearby, while others may not nest at all. Pollution and degradation of their marine habitat also threaten the turtle's survival.
A fairly recent phenomenon recorded in Hawaii's population of sea turtles as well as in populations off the coast of Florida is the presence of a disease called fibropapilloma. Fibropapilloma causes the growth of large bulbous tumors predominantly on the soft tissues of the turtles. Once turtles are stricken with the disease they do not appear to recover. The tumors often spread to many parts of the body, ultimately killing the turtles. While the exact cause of the disease is not known, scientists suspect that a virus, parasite or the effects of marine pollution may be involved. A survey conducted in Kaneohe Bay on the island of Oahu in 1991 indicated that more than 50% of the sea turtles in the Bay are affected and 36% off the island of Molokai.
Sea turtles, as well as other sea turtles in Hawaii, are fully protected under both the federal Endangered Species Act (see Appendix 2) and under Hawaii state law. These laws prohibit hunting, injuring or harassing sea turtles or holding them in captivity without first obtaining a special permit for research or educational purposes. Swimmers and divers should be aware that riding sea turtles is illegal as it puts the animals under unnecessary stress. Fines for violating these laws protecting turtles can be as high as $100,000 and may even include some time in prison.
Under provisions in the Endangered Species Act, the National Marine Fisheries Service, the U.S. marine fish and Wildlife Service and the State of Hawaii's Department of Land and Natural Resources have recently formed a recovery team to help restore Hawaii's sea turtle population to previous levels. The goals of the recovery team are to identify research, management and enforcement needs for effective sea turtle conservation in the islands as well as promoting sea turtle protection through public education programs.
International trade in sea turtle parts of products is also illegal under an agreement known as the Convention for International Trade of Endangered Species of wild fauna and flora, or CITES (see Appendix 2). Unfortunately, trade in sea turtles and their products continues at an alarming rate even though it is against the law. International trade currently focuses on two major markets: tortoise shell, which is used to make jewelry, eyeglass frames and ornaments, and small leather goods. Two species of sea turtles other than the sea turtle are hunted primarily for these markets. They are the Hawksbill and the Olive Ridley, both sighted in Hawaiian waters. When returning from a foreign country, it is illegal under CITES for United States citizens to bring any sea turtle products into the country. Violators may be fined up to $20,000 and be sentenced up to one year in prison.
Species Information - Sea Turtles
Sea Turtle Protection and Conservation
Sea turtles are graceful saltwater reptiles, well adapted to life in their marine world. With streamlined bodies and flipper-like limbs, they are graceful swimmers able to navigate across the oceans. When they are active, sea turtles must swim to the ocean surface to breathe every few minutes. When they are resting, they can remain underwater for much longer periods of time. Although sea turtles live most of their lives in the ocean, adult females must return to land in order to lay their eggs. Sea turtles often travel long distances from their feeding grounds to their nesting beaches. Scientists are studying how sea turtles find their nesting beaches.
Help from a Common Man
- You can help turtle researchers by reporting nesting, basking, injured, or dead sea turtles in Hawaii to the Hawaii State Department of Land and Natural Resources, Division of Aquatic Resources at (808) 243-5294 or the National Marine Fisheries Service in Honolulu at (808) 983-5730. Mistreatment, harassment, or killing of sea turtles should be reported to the Enforcement Division of the National Marine Fisheries Service at 800-853-1964 or the State Conservation and Resources Enforcement Maui office at (808) 984-8110. For information on sea turtles call Pacific Whale Foundation, (808) 249-8811.
- When snorkeling, always give sea turtles at least 10 feet of space, and donít block the path of a surfacing sea turtle.
- Participate in the nation-wide beach clean-up held every September.
- Never throw cigarette butts on the beach or out your car window.
- Dispose of your garbage properly.
- Reuse your plastic bags, and dispose of them properly.
- Take cans, bottles, used motor oil, batteries and newspapers to recycling centers.
- Do not release balloons for parties or any other event!
- We can all help protect the Hawaiian Green Sea Turtle by immediately reporting any sightings of mistreatment, harassment or killing of sea turtles.