Term Paper on "Endangered Species Green Sea Turtles"

Term Paper 5 pages (2208 words) Sources: 4

[EXCERPT] . . . .

Endangered Species

Green Sea Turtles are an endangered species of reptiles, one of the few animals to have seen the mighty dinosaurs grow extinct. Sea turtles are as old as 200 million years, and are now on the verge of extinction because of the son of man.

The scientific classification of Green Sea Turtles is:

Kingdom: Animalia

Phylum: Chordata

Reptiles

Order: Testudines

Family: Cheloniidae

Genus: Chelonia

Species: C. mydas

Binominal Name: Chelonia Mydas (given by Linne, 1758)

There are seven remaining species of sea turtles: the Green Sea Turtle, the Leatherback turtle, the Hawksbill, the Olive Ridley, the Flatback, the Loggerhead and Kemp's Ridley. Of these, only the first four live in the Hawaii's, and the Flatback turtle can only be found on the northern coasts of Australia.

Green Sea Turtles are, just as the majority of modern reptiles, cold-blooded (their body temperature is not constant, it depends on the environment) animals, covered in a bony shell that protects them from being attacked by predators. This shell covers both the belly and the back of the turtles (the ventral and dorsal parts), as they are known to be slow-moving animals with no other defense system.

Although sea turtles basically have to crawl their heavy bodies on land, they are rapid swimmers - their front and rear limbs have developed into flippers, allowing them to cover up to 35 mph underwater; also, their shells are lighter and streamlined then the ones of land turtles, and more aero dynamical.

Sea turtles can remain underwater for more than two minutes when active, and when they are asleep their respiratory system allows them more than two hours of sleep without coming to the surface to breathe. Turtles are able to store higher concentrations of oxygen in their blood and muscles, and more carbon dioxide also. At young sea turtles though, this ability is not developed yet and when they sleep, they do it afloat.

Exceeding the breathing and locomotion-related features, the sea turtles also possess an ingenious system that enables them to get rid of the salt accumulated over time: behind their eyes lays the salt gland, with the help of which they "shed tears" of salt.

Baby turtles only weigh about one ounce but when reaching adulthood they can weigh up to 4-500 pounds and measure up to 4 feet. There are seven different species of sea turtles and the largest of all, the giant of all reptiles, is the Leatherback; it can grow up to 200 pounds, but it does not nest in Hawaii.

The exact life span of sea turtles is not known, but they can easily reach 150 years. It takes them 20 to 50 years to reach sexual maturity only, and this is one of the reasons why their species is endangered.

Scientists believe that nesting female sea turtles return to their natal beach to lay eggs- the beach where they were born- and than can mean migrating for as much as 800 miles from their feeding grounds. The migration generally takes place in late spring, and the most frequented nesting beaches are on French Frigate Shoals, on which an estimated 90% of the Hawaiian green turtles mate and lay eggs. The male accompanies the female, with which he mates offshore. Females only lay eggs once in 2 to 4 years, and they crawl themselves ashore only at night. In an interval of two weeks, they can lay as many as 9 clutches. Each clutch contains a large number of eggs, from 75 to 200.

The incubation process takes between 45 and 75 days (depending on the temperature), at the end of which baby turtles come out. They emerge out of the egg using an interesting tool: an egg tooth, with the help of which they chip away at the eggshell. The egg tooth is a protuberance on their beaks.

After hatching, baby turtles dig their out of the sand in a several-days' group effort. If they would do it individually, they wouldn't be able to make it to the surface. When the group of newly-hatched turtles reaches about an inch away from the surface of the beach, they stop to check the temperature of the sand. If it feels hot, they wait. Heat means it is daytime outside, and at daytime, baby turtles are more exposed to predators and dangers. So they wait until the sand gets cooler, a sign that night has come. In order to reach the sea, turtles guide themselves for the brightest horizon. This is why many of them get lost and die on the beach in the past years: artificial lights made by man lead them into confusion.

After reaching the water surface, young turtles must swim continuously for the next two days, and they only come ashore again after a year.

Adult green sea turtles are herbivores, feeding on algae and marine grass. Their youngsters though, feed on jellyfish and other invertebrates, which makes them carnivorous.

Turtles are hard to breed because they do not nest every year and they are exposed to many predators until reaching maturity: crabs and prey birds, sharks and other carnivorous fish.

Green Sea Turtles can be found in the fairly shallow waters of lagoons, shoals, bays and coral reefs.

Green sea turtles have also developed a special feeding arrangement: on their back, one can sometimes find patches covered in algae, on which fishes feed. It is a very good example of mutualism (a type of symbiosis in which both species have something to win): the fish receive food and the turtles get their shells cleaned.

Green Sea turtles can be found worldwide in tropical and subtropical waters. Nevertheless, from the millions of members of the species, only approximately 200,000 have remained today and this number declines. In Hawaii, only 100 to 350 females are considered to hatch every year. There are many reasons for this critical situation, although grown-up sea turtles have only two real enemies: humans and sharks.

Humans are the prime factor of the decline of green sea turtles, for several reasons:

Hunting: sea turtles have been hunted for centuries, for a multitude of uses: their shell is used to make jewelry and other ornaments, their meat and eggs are an excellent gastronomical rarity, their skin is hunted for small leather goods and their fat is used for oil. Practically nothing of the beautiful animals is left unused by humans. Their rarity turns them into even more precious prey, and their price on the market grows, despite the regulations and laws that ban both hunting and hurting or harassing these animals.

Incidental take: thousands of Green Sea Turtles are accidentally killed every year by channel dredging and commercial shrimp fishers: the turtles get caught and entangled in the coastal grill nets, longines and driftnets. Lately, the laws have been changed to oblige shrimp fishers to use TEDS, turtle excluder devices, but many of them do not abide these laws. Another reason for the large hunting of turtles is that they are very predictable, at least when nesting. After laying their eggs, female turtles return at sea crawling and they leave visible marks on the sand. That makes it easy for humans to discover the clutches and take the eggs out. The unborn baby turtles don't stand a chance.

Marine debris: it can prove to be lethal to Green Sea Turtles when they are mistaken for food and eaten. Plastics are easy to be mistaken for food, and they are not digested by the turtles' stomachs. Plastics remain in their bodies for a long time and release toxic substances or block the digestive system causing them to starve.

Oil spills: like plastics, oil or tar balls have been found in the stomachs of dead Green Sea Turtles, and there have been many oil spills in the marine waters in the past years; that leads to other concern reasons.

The degradation of the habitat and coastal development: because of these, fewer familiar nesting beaches are left every year for the Green Sea Turtles. Turtles need quiet, lonely beaches in order to nest, and noise, lights and coastal obstructions act as artificial inhibitors. As a result, turtles either choose to nest on less populated and developed beaches nearby, or don't nest at all.

Fibropapillomatosis: fibropapillomatosis is an extremely alarming disease that has been endangering Green Sea Turtles in the past years. It develops in the form of multiple tumors on the skin and ultimately internal organs, protuberances that prevent turtles from swimming, breathing, mating, eating and seeing. In the end, it is impossible for the animals to survive in these conditions and they die. Scientists have been studying the disease in hope of finding a cure for the fibropapilloma virus in the future.

Although unseen by many, Green Sea Turtles are of a great environmental value: they play key roles in at least two ecosystems and their extinction will not only affect other sea animals but humans also.

First, there are the oceans. The Green Sea Turtle… READ MORE

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