The biology of the sea turtle and facors affecting its population
Upon first sight of the great sea turtle it might just think that it is like any other turtle. The truth is that marine turtles are beautiful creatures spending a majority of their lives wandering endlessly through our massive ocean. These reptiles have the ability to do amazing things. Some of these things include evolving to a range of purely innate responses to the demands of a changing suite of environments and having remarkable navigations skills for their excursions that may last up to several years. Sea turtles have been in existence for more than 100 million years and researchers have been studying them for great deal of time. During the past 20 years however, the natural history of marine turtles has received growing attention and much has been learned (Bjorndal 19). Instantly you will fall in love with their beauty and majestic way of life.
The biology behind these amazing animals causes them stand out from much of the ocean life. There are seven different species of sea turtles. These species include Kemps Ridley, Flatback, Loggerhead, Olive Ridley, Leatherback, Hawksbill, and the Hawaiian Green Turtle (Gardner 2004). Unlike many animals the female sea turtle is generally larger than the males. The main distinction between the two is that the male tends to have a longer tail. The core part of the sea turtle and the part that helps protect them from predators is the shell. The shell grows around the body protecting the organs of the animal. There are different sections that cover the shell, which are called scutes. The skin that covers their body is a leathery material. Marine turtles also have a beneficial shape that allows them to glide through the water with their paddle-like flippers. These flippers provide the main movement and mobility of the turtles and contain a claw and in some cases two claws.
Courtship between among sea turtles begins when the male turtle first approaches the female it swims round to face the female and nuzzles her head. Continued nuzzling on the neck and shoulder accompanied by nonaggressive bites leads to biting actions at one of the rear flippers. If the female accepts she will turn toward him and assume a vertical position in the water (Bjorndal 30). The male will the attempt to mount the female and reproduction occurs between the male and female through sperm that is passed to the female though the males tail. The beginning of mating takes place in the water and then concludes on land (Ching 21). A sea turtle lives most of its life in the water, however the female will return to land to lay her eggs. Biologist believe that nesting female turtles return to the same beach where they were born. This beach is referred to as the natal beach: (Gardner 2004). The female sea turtle will lay her eggs at nighttime, making her way up on to the land to find a good place to construct a pit for her offspring. The process of laying eggs is as follows: she dug a pit for her body with her flippers. She nested in it and used her back flippers, like shovels, to scoop out a bottle-shaped hole. Now she drops about one hundred white, leathery eggs that look like ping pong balls into this hole. When she finishes she will cover the nest with sand and slowly go back to sea, leaving a trail behind herÓ (Jacobs 13).
Heat from the sun helps the growth and development of the unhatched sea turtles. Usually two months are needed for the eggs to hatch. When they have reached maturity they have a sharp snout that they uses to cut open and escape from the shells. A nest of sea turtles will hatch at about the same time. This is beneficial because the movement as a group helps each egg. When the baby sea turtles are out of the shells they start scraping away the sand when they feel the cool sand and then they know that it is night. The little hatchlings will spend a couple of days digging its way to the surface. Once they have reached the surface they make their way towards the ocean. Only a few make it to adulthood. They have many predators like birds and lizards on the beach and even the fish will eat them in the ocean. If they do make it to the ocean they have a chance to live a long adventurous life.
Sea turtles are not generally considered social animals, however some species do congregate offshore. Even hatchlings, once they reach the water, generally remain solitary until they mate. In the ocean turtles may spend hours at the surface floating, apparently asleep or basking in the sun while seabirds perch on their backs. Sea turtles tend to dive in a cycle that follows the daily rising and sinking of the dense layer of plankton and jellyfish. As dawn approaches, their dives become deeper as the plankton and jellyfish retreat to deeper water and away from the light of day. The turtles bask at the surface at midday when the layer sinks beyond their typical diving range. As dusk approaches, the turtles' dives become more shallow as the layer rises.
Migration habitats are different among species and different populations of the same species as well. Some sea turtle populations feed in the same general areas and other will travel great distances. The Green sea turtle population migrates primarily along the coasts from nesting to feeding grounds. However, some populations will travel across the Atlantic Ocean from the Ascension Island nesting grounds to the Brazilian coast feeding grounds. Researchers have documented nonmigratory and short-distance migratory populations among sea turtles. Leatherbacks have the longest migration of all sea turtles. They have been found more than 4,831 km (3,000 miles) from their nesting beaches.
A sea turtles diet also varies with species. Some maybe be carnivorous, others herbivorous, or both plant and meat eating. The jaw structure of the species can indicate their diet. Marine turtles with finely serrated jaws are more adapted for a vegetarian diet of sea grasses and algae. The Loggerheads and Ridleys have jaws that are tailored for crushing and grinding crabs, mollusks, shrimps, jellyfish, and vegetation. The hawksbill has a narrow head with jaws meeting at an small angle, adapted for getting food from crevices in coral reefs. They eat things like sponges, tunicates, shrimps, and squids. As sea turtles age they sometimes change their eating habits from carnivorous at hatching and to a herbivore as an adult.
Sea turtles can be spotted around the globe. Adults of most species are found in shallow, coastal waters, bays, lagoons, and estuaries. Some also venture into the open sea. Younger sea turtles of some species may be found in bays and estuaries, as well as at sea.
Despite the abundance of interest and love of sea turtles they are still endangered. There are many factors that contribute to the threatened lives of sea turtles. One main cause of the death of sea turtles is from hunters. Marine turtles are hunted for their meat, eggs and their shell, which is usually used for tools and ornaments (Olafsson and Daly 2). Their skin is often used to make leather goods. The Hawksbill is prized for its shell to make tortoise shell combs, brush handles, eyeglass frames, buttons, hair clips and jewelry (Jacobs 21). Sea turtles are even killed and then stuffed to be hung on peoples walls. Once dead fat is taken from these reptiles to make makeup. Now the sea turtles are under the Endangered Species Act. This has helped them make a slow recovery and the population is slowly increasing.
Sea turtles are amazing animals for their beauty and intelligence. They have roamed our oceans for millions of years and hopefully with our help we can keep it going. Now that you have learned more knowledge about sea turtles here are a few interesting facts: Scientists believe that sea turtles navigate by using their own innate global positioning system. Hatchlings are born with the ability to navigate using the earth's magnetic field. The leatherback is the most ancient species of living sea turtle, as well as the largest and heaviest turtle in the world. Studies have shown that loggerhead eggs incubated at about 90 degrees F (32 degrees C) or higher develop into females. Eggs incubated at 82 degrees F (28 degrees C) or below produce males. Incubation temperatures between the two result in both males and females.
Works Cited
Ancona, George. (1987). Turtle Watch. New York: Macmillan Publishing Company.
Bjorndal, Karen A. (Ed.). (1979). Biology and Conservation of Sea Turtles. Washington & London: Smithsonian Institution Press.
Bolton, Alan B., & Blair E. Witherington. (2003). Loggerhead Sea Turtles. Washington: Smithsonian Books.
Bush Entertainment Corporation. (2002). Sea Turtles. Retrieved March 31, 2004, from http://seaworld.org
Ching, Patrick. (2001). Sea Turtles of Hawaii. University of Hawaii Press. 
Committee on Sea Turtle Conservation. (1990). Decline of the Sea Turtles: Causes and Prevention. Washington, D.C.: National Academy Press.
Florida Marine Research Institute. (2004). Sea Turtles. Retrieved March 31, 2004, from http://flordiamarine.org
Fugazzotto, Peter, Todd Steiner. (1998). Slain by Trade. Sea Turtle Restoration Project.
Garder, Emily M.S. (2004) Hawaiis Marine Wildlife: Whales, Dolphins, Turtles, and Seals: A course study. Retrieved April 19, 2004, from http://www.earthtrust.org/wlcurrie/index.html
Jacobs, Francine. (1995). Sea Turtles. Hawaiian Island Humpback Whale National Sanctuary and the U.S. Fish and Wildlife Service.
Klemens, Michael W. (Ed.). (2000). Turtle Conservation. Washington & London: Smithsonian Institution.
Olafsson, Hugi, Trevor Daly (1990). Sea Turtles: Endangered and Exploited. Spachee Environmental News Alert no. 2.