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Sea turtles

Page history last edited by Knol, Alivia 15 years, 1 month ago

Alivia K.

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 Sea Turtles 

   

          

          Turtles have a reputation for their comical slowness, sluggish movements, and rock-like form, but a cousin of this household box turtle swims across oceans and lives up to 150 years sometimes. Sea turtles have strayed quite far away from this reputation of laziness and a boring lifestyle. They are elegant and graceful, even though some sea turtles have weighed almost a ton.  You would think an enduring and well designed creature like this would be highly evolved and adapted, this is not so. Sea turtles date back to the Mesozoic era and yet their form has changed very little since then. What sea turtles should have a reputation for are their seven diverse species, predator-proof anatomy, and most urgently, a spot on the endangered list.

 

Anatomy

“Turtles are generally described as being persistent in form, deliberate in behavior, late maturing and long lived,” says herpetologist Blair Witherington, in her book Sea Turtles. This is a very good way to sum up a turtle’s anatomy and lifecycle, ‘persistent’ and ‘long lived’. Sea turtles are comfortable with a world that we don’t know much about, considering that they spend almost all of their lives under water. This section is a look into the other-worldly anatomy, life cycle and nesting habits of the sea turtle.

Any structure that has remained constant since the time of dinosaurs has to be pretty tried-and-true. That is the story of a turtle’s anatomy, simple but proven to work. The basic body structure of a sea turtle is composed of two main things: the carapace and the plastron. The carapace is basically the upper shell or exoskeleton of the turtle, in most turtles it consists of roughly 50 bones. The shell is made up of the turtle’s ribcage and spine, which are fused together by bony plates that form a hard shell. This structure is covered by a layer of skin and scutes, which are horny plates, protecting the shell from scrapes and bruises. The plastron is the lower shell of the turtle, a sort of chest protector, which is mostly a continuation of the carapace. It is nearly flat and composed of about 9 bones in most turtles.  It too is covered in a layer of scutes. Other than its box-like shell, a turtle has four limbs, a movable jaw without teeth, and an extended skull that can retract into the turtle’s body. This smart engineering makes it more than a little difficult for predators to crack a turtle’s shell.

A sea turtle’s life cycle is a grueling one; well, for a female at least. A female sea turtle can lay over 100 eggs in one clutch, or a nest of turtle eggs. As if that is not enough, a sea turtle can have six or more clutches in an egg laying season. All together, a sea turtle will lay 400-1,000 eggs per season. A sea turtle egg develops for 45-55 days, sometimes more. Following the incubation period, the surviving hatchlings break through their eggs and crawl to the ocean at the same time. The hatchlings do this at night and have to fend for themselves, avoiding sea gulls and crabs as they prey on the hatchlings. The fast hatchlings find their way to the shore without being eaten, but they are not totally out of the woods yet. The first 10 years of a sea turtle’s is the most dangerous because the turtle is not very fast. The turtle will make its way to the safer, open waters of the ocean and live there until it is a young adult (5-20 years). Then it will swim nearer to the coastline to wander and feed. After this stage, the adult turtles migrate to breeding areas. The females then return to their own nesting beaches to lay their eggs every two to three weeks. The female will stay in shallow water between nesting periods. A sea turtle can live up to 80 years, sometimes more.

The nesting process for a sea turtle is very fascinating. It starts when the female sea turtle digs a two-foot deep hole in a sandy beach, then she lays her clutch of about 80 ping-pong ball sized eggs. If all goes well, the nest will be safe from sand erosion and predators, even without the protection of a mother. At first, each egg has a small dimple but is pressed out when the egg absorbs moisture from the damp nest.  After a couple of weeks, the gender of the turtle will be decided. Under cool conditions (less than 29˚ C or so) the incubating eggs will become male and under warmer conditions, the eggs will become female. After the eggs are fully incubated, the turtles will use their caruncle, or egg tooth to peck their way out of the papery shell. Over a day or two, all of the hatchlings will have broken through their shells. There is a pocket of air within the nest that will give the hatchlings room to start pushing to the surface. All of the hatchlings push their way through their sandy covering at the same time. This united effort is the first of many challenges that a walnut-sized, baby sea turtle will haveto face during its life.

 

Species

Sea turtles are an uncommon and mysterious group of animals as it is. What would you tell me if I told you that there are seven species of sea turtles? Or maybe eight. There is a debate as to whether there is an eighth species or not. Would that make it even more complex? I thought so. And not to mention that each species has widely varied traits. One species grazes on seagrass and can swim at up to 20 miles per hour at times. Another species has absolutely no scales and has been recorded to weigh up to 2019 lbs. We’ll cover the seven confirmed species and what makes them so unique.

 

Green Turtle- Chelonia Mydas

            Green turtles are streamlined and strong swimmers. They are the largest of the hard shelled sea turtles and contrary of their name, do not appear green. Instead, they have green tissues on the underside of their bodies. It is more likely that these turtles were named for their meat that humans consumed, considering their nicknames ‘Soup Turtle’ and  ‘Edible Turtle’. The actual shell color of the Green turtle is brown or olive with occasional light and dark patches. Unlike some turtles, the green turtle’s shell has no barnacles or other creatures on its surface. Adult females are 175-485 lbs., males are slightly smaller. The Green turtle lives in tropical and warm marine waters worldwide.

 

Loggerhead Sea Turtle- Caretta caretta

            The Loggerhead has a worn, tough appearance and is masculine looking when compared to a graceful green turtle. Its shell is covered in algae, large barnacles and other clinging things, but the actual shell is dark reddish-brown with smears of orange, red, brown and black. The Loggerhead’s neck and head are almost always golden yellow. The Loggerhead sea turtle lives where the climate is warm, and occasionally near the equator. Adult females weigh between 155-375 lbs., the males are slightly larger.

 

Hawksbill Turtle- Eretmochelys imbricata

            Hawksbill turtle’s are striking turtles. The Hawksbill has a heart shaped shell that is covered in complex patterns. These can be found in pretty much any form: overlapping bursts, zig-zags or irregular splotches. No two Hawksbill shells are exactly alike. Their vibrant colors (cream, amber, rusty red, brown, black) carry onto their flippers and head, making the Hawksbill a beauty from head to toe. Unfortunately, this beauty is occasionally covered up with coarse scratches on the surface of the shell, from rock and coral. The scutes on a hawksbill overlap and taper toward the back of the shell, forming sharp Vs and Ws. The Hawksbill also has a narrow, bird-like bill, thus the name. An Adult female weighs between 88 and 176 lbs. This turtle lives in the tropical marine waters of the Atlantic, Pacific and Indian Oceans.

 

The Ridleys

Olive Ridley- Lepidochelys olivacea

            The ridley species are two with many similarities, but they do have some distinguishing features. The olive ridley is the smallest sea turtle, though very similar in size to the Kemp’s. It weighs 77-100 lbs. and has a straight shell length of 25-30 in. The olive ridley has a heart shaped, almost circular shell that is a drab olive green color. This turtle has a greater and more variable amount of scutes than other sea turtles. It has 6-9 vertebral scutes, where a Kemp’s Ridley has 5. The olive ridley lives in the tropical marine waters of the Atlantic, Pacific and Indian oceans.

Kemp’s Ridley- Lepidochelys kempii

            A Kemp’s ridley has a more circular shaped shell than most sea turtles do. The flared edges of its shell often make it wider than it is long. Its shell is olive gray in color displays no barnacles. These turtles may be small (if the weight of a German shepherd is what you consider small) but they are fast and mean. In comparison to its relative, the Kemp’s ridley has a broader, less triangular shaped head and broader shell than the Olive ridley. Similarly though, the Kemp’s weighs 75-100  lbs. and has a straight shell length of 25-28 in. The Kemp’s ridley lives in the Gulf of Mexico and in warm, temperate waters, especially between the coast of Florida and Massachusetts.

 

Flatback Turtle- Natator depressus

            The Flatback turtle is unsurprisingly flat. The edges of its shell is turned up like the rim of a hat, giving the shell at least a little shape. The Flatback is olive gray in color and has thin, oily scutes that can easily be scratched through. The Flatback turtle may be the cleanest of the sea turtles, free of barnacles because of the oily feel of its shell. One unique trait of the Flatback turtle is that on calm days, it may spend hours on the surface of the water. An adult female Flatback turtle weighs between 155-175 lbs. and males are slightly smaller than females. These turtles live in tropical marine waters between northern Australia and New Guinea, nesting exclusively on Australian beaches.

 

Leatherback Turtle- Dermochelys coriacea

            Leatherback turtles are massive. Adult females weigh 440-1320 lbs, with a straight shell length of 4ft 9in-5ft 7in. Leatherbacks are sleek, dark, scale-less turtles with long, wide flippers. The Leatherback has broad shoulders and a barrel shaped body with seven distinct ridges along the carapace. Their topsides are black with random white splotches. The underside of a Leatherback is black and white and often blushes to pink when on a nesting beach. Also, each Leatherback turtle has an irregular pink spot on the top of its head, and like fingerprints, no two spots are the same exact shape. Other than its record braking size, the Leatherback has the largest distribution of any sea turtle. It lives as far north as British Columbia and the British Isles and as far south as the Cape of Good Hope and New Zealand.

 

Conservation

          Until recently, sea turtles have not had to face their most threatening challenge. Intruding upon their nesting grounds, contributing to drastic climate change and trapping them in our nets, humans have been a deathly predator for sea turtles. All species of sea turtles are now endangered or threatened. The Leatherback, Kemp’s ridley, and Hawksbill sea turtles are critically endangered. Olive ridley and Green turtles are endangered, while Loggerheads are threatened and the conservation status of the Loggerhead is unclear. Sea turtles face many threats imposed by humans, justified only by rescue centers that are trying to help sea turtles around the world.

            Sea turtles have faced many threats since people started hunting them for their meat and shells. Today, marine debris and abandoned fishing nets pose a threat because the turtles get entangled in the nets and are unable to surface for air. Sea turtle eggs are occasionally gathered for consumption and poachers hunt the turtles for their shells to put on the black market. Shrimp and fishing nets trap sea turtles in their nets causing thousands of turtle deaths a year. Beach development also poses a threat to these animals because sea turtles return to the same beaches to nest.

            There are many sea turtle rescue centers around the world with the main goal of reversing the damage that humans caused to this group of animals. Some rescue centers help to nurse injured sea turtles, some work to make the nesting process safer for mother turtles and hatchlings. Some examples of these centers are the Mote Marine Lab in Sarasota, FL.; Clearwater Marine Aquarium in Clearwater, FL.; Sea Turtle Inc. organization in South Padre Island, TX and many more. Another thing that can help the conservation of sea turtle is fishing equipment that avoids trapping turtles. This equipment can be simple things like larger hooks and traps that allows sea turtles to escape if they do get trapped. This specialized equipment has reduced  the entrapment of turtles by 97%. Recently, researchers in the Caribbean and other places have succeeded in assisting a comeback for sea turtles. Hopefully, this is a signal that there is hope for bringing back the number of sea turtles.

            The sea turtle. The largest turtle, the strongest turtle, the fastest turtle. It is a species of record-breakers, a mysterious species, worthy of being studied. This ocean dwelling reptile is  elegant and enduring, graceful and well designed. It deserves no reputation of being boring or slow, but instead one of being fascinating, because it is just that.

 

Bibliography

         

"Carapace." Wikipedia, The Free Encyclopedia. 30 Jan 2009, 03:38 UTC. 23 Feb 2009 <http://en.wikipedia.org/w/index.php?title=Carapace&oldid=267335257>.

 

"Diet and Eating Habits." Sea Turtles 10 Feb 2009 <http://www.seaworld.org/infobooks/SeaTurtles/stdiet.htm>.

 

"Sea turtle." Wikipedia, The Free Encyclopedia. 12 Feb 2009, 23:30 UTC. 23 Feb 2009 <http://en.wikipedia.org/w/index.php?title=Sea_turtle&oldid=270326214>.

 

"Sea Turtle Information." Caribbean Conservation Corporation 10 Feb 2009 <http://cccturtle.org/sea-turtle-information.php/page=species_world>.

 

"Turtle."  16 May 2008.  HowStuffWorks.com. <http://animals.howstuffworks.com/reptiles/turtle-info.htm>  21 February 2009.

 

Witherington, Blair. Sea Turtles: An Extraordinary Natural History of Some Uncommon Turtles. St. Paul, MN: Voyageur Press, 2006.

 

 

Comments (3)

Knol, Alivia said

at 10:49 am on Feb 24, 2009

yaaayyy! It's up!!!

Chuang, Caitlin said

at 5:09 pm on Feb 25, 2009

I love your pictures!

Price, Brittany said

at 9:04 am on Mar 6, 2009

thanks a million. thanks for uploading your page on time. i'm helping mr.kabodian finish. great repot.,

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