Sea Turtles

 

Sea Turtles are large turtles that spend most of their lives in the seas. They live in shallow coastal waters of warm and temperate seas. There are many types of sea turtles, including the Loggerhead (Caretta caretta), the Green Turtle (Chelonia mydas), the Leatherback (Dermochelys coriacea), the Flatback (Natator depressa), and many others. All Sea Turtle species are considered endangered or threatened.

Anatomy: These cold-blooded animals are strong swimmers and good divers. They have four flipper-like legs and a shell that is attached to their backbone. They cannot pull their head and legs into the shell. These turtles vary in color from shades of brown to green to black. Sea turtles vary in size from 2 to 6 feet (0.5 to 1.9 m) long, weighing 78 to 1900 pounds (35 to 870 kg). During active times, turtles must go to the sea's surface every few minutes in order to breathe air.

Diet: Most sea turtles are carnivores (meat eaters), but the green turtle is an herbovore (a plant eater that eats sea grass and algae). Most sea turtles eat crustaceans (crabs, lobster, shrimp, and other shelled invertebrates), shellfish, jellyfish, Man-of-War, and small fish.

Reproduction: Adult female Sea Turtles return to the beach where they were born to lay up to 200 soft-shelled eggs in the sand. When the baby turtles hatch, they immediately head for the nearby water. Many young turtles are eaten by birds and other predators during this difficult trip. It has been estimated that only 1% of these hatchlings will reach adulthood. No one knows how the females find the beach where they were born.
 

 

How big is a loggerhead turtle?
Loggerheads normally weigh 170 to 315 pounds and attain a length of 31 to 49 inches.

What kind of animal is a loggerhead?
Loggerheads, like all sea turtles, are reptiles. They are related to land turtles, lizards, and snakes.

What do loggerheads eat?
Loggerhead turtles sometimes eat hard, shelled animals such as crabs and clams. They also feed upon sponges, jellyfish, mussels, clams, oysters, shrimp, and a variety of fish. They eat jellyfish? Yet another reason to love loggerheads!

Why are loggerheads endangered?
Since 1983 the population of the Loggerhead Turtle has declined by more than 50%, making it an endangered species. Loggerhead populations have declined from historical levels because of coastline development and disturbance of beaches by human activities such as cleaning, driving, and artificial lighting; collecting eggs; destructive fishing practices; pollution; and the dumping of trash into the ocean.
Throughout their life, Loggerheads are exploited as a food source by some cultures and for their shells which are used in some manufacturing processes. They are also harmed and killed by the propellers of high speed boats and the swallowing of discarded rubbish such as plastic bags and fishing lines. In addition, modern day fishing techniques such as trawling for prawns and fish, can cause turtles to become entangled in the nets and drown.
The leading cause of loggerhead mortality is drowning in shrimp and fish nets. In 1978, the National Marine Fisheries Service (NMFS) began a program intended to prevent the drowning of turtles in shrimp trawls. A cage-like design called a turtle excluder device (TED) was developed to be installed within the trawl. Since there was a lack of widespread use of these devices on a voluntary basis, NMFS promulgated regulations requiring their use.
Protection of marine habitat is extremely critical to the loggerhead's continued survival. The beaches where they nest must continue to be protected. In addition, measures must be taken to prevent further loss and degradation of marine habitat from pollution, coastal development, and offshore oil and gas development.

What should I do if I see a nesting loggerhead?
If you are fortunate enough to see a mama turtle, here are some simple rules to follow:

Never walk on the beach with a flashlight or shine a light in the sea turtle's face. The light may cause the female to abort the nesting process, or other sea turtles nearby may be discouraged from nesting if there are lights on the beach.

Do not take pictures using flashes. This high-intensity light can be even more disturbing than the flashlights.

Stay clear and out of sight of the turtle until she begins laying eggs, otherwise you may scare her back into the sea.

For your safety, stay away from the turtle's head. Sea turtles, especially loggerheads, have very strong jaws and can harm you if provoked.

Do not handle the eggs or put any foreign objects into the nest. You can introduce bacteria or injure the eggs.

Do not handle or ride the sea turtle. In addition to being illegal, you may injure the turtle or cause her to leave without finishing nesting.

Do not disturb tracks left by turtles. Researchers sometimes use the tracks to identify the type of turtles that nested and to find and mark the nests.

How can I help ?
There are many things individuals can do to help loggerheads survive.

Become informed about the things that are killing sea turtles or destroying their habitat. Elected officials make decisions every day that impact these issues. As an informed citizen you have the power to influence your officials. Make your voice heard!

Remember that we share our beaches and environment with many other species.

Take responsibility for your own actions. By reducing the amount of plastic garbage, recycling, and not leaving trash on the beach, you are helping preserve the turtle's habitat.

Turn out lights at night. Hatchlings head toward the light, normally the stars and moonlight hitting the water. They also will head toward artificial lights such as floodlights and porch lights - and all the perils in that path such as cars and people. Brightly lighted beaches also can deter nesting females.

Report nest abuse. If you notice that a nest has been disturbed, call 1-800-922-5431.

Remove debris and furniture from the beach to prevent harming turtles who may eat unsuitable items or get tangled in them.

Fill in holes in the sand so hatchlings can make a quicker escape to the water.

Allow hatchlings to crawl. It's tempting to pick up the cute little guys and help them along, but let them be. It's important that they "imprint" on their native beach.

Why do the mama turtles "cry" while nesting?
During the nesting process, the female Loggerhead appears to be crying with liquid flowing from her eyes. This "crying" serves two very useful purposes:
1. It is her way of excreting the excess salt acquired from drinking sea water.
2. It flushes sand from her eyes.

When does loggerhead nesting season start on Pawleys?
Typically the mama loggerheads begin nesting the second week of May. The past two years they have begun on Mother's Day weekend!

When does hatching season start?
Generally the hatchlings emerge from the nest fifty-five to sixty-five days after the eggs were laid.

Can you tell whether the hatchlings will be boys or girls?
Not really. However, warm sand produces mostly females and these eggs hatch in the shortest time. Cooler sand produces mainly males and the eggs take longer to hatch.

 

When do loggerheads reach sexual maturity?
It is estimated that loggerhead turtles reach maturity between 20 and 30 years of age and have a maximum reproductive lifespan of about 30 years.



 

TURTLE NESTING SEASON  - Pawleys Island 2007

Keeping shy creatures safe

Turtles' annual crawl to the dunes fretted over by vigilant volunteers

By Kelly Marshall Fuller - The Sun News

Wednesday was no ordinary stroll on the beach for Mary and Phil Schneider.

The two, who wore colorful, matching T-shirts, were on the prowl for misplaced loggerhead turtle nests, sprigs of beach vitex and the possibility of sea creatures who sometimes strand on the beach.

The hard work started this week for the two longtime S.C. United Turtle Enthusiasts: The official start of loggerhead turtle nesting season began Tuesday.

The Schneiders, who help coordinate about 50 turtle volunteers in Litchfield and Pawleys Island, expect to be on the beach two to three times a week this summer.

On their off days, they will continue to take calls from other volunteers who find stranded turtles or need assistance moving a nest out of harm's way.

There have been no turtle nest sightings on the Grand Strand yet, but Mary Schneider expects that to change in the next several weeks.

The couple is optimistic that the loggerhead turtle will show stable numbers this summer along the Grand Strand.

There were five turtle nests found in 2005 at Huntington Beach State Park, said Jennifer Koches, with the U.S. Fish and Wildlife Service. In 2006, the park had 14 nests.

The area of Debordieu, Pawleys Island and Litchfield had 62 nests in 2005 and 80 in 2006, Koches said. Three nests were located at Myrtle Beach State Park in 2005. No nests were found at Myrtle Beach State Park last year, Koches said.

SCUTE volunteers have been patrolling a 55-mile stretch, between Little River and Georgetown, for about 22 years. Other parts of the state also have volunteer organizations to protect loggerhead turtles.

"We hope that we will see the results of saving the turtle nests," Mary Schneider said. "We want to do what we can to preserve the species."

Travels of Loggerhead Hatchlings That Come Off Our Beach

Biologists studying young Loggerhead turtles in the Mediterranean Sea were startled to find from their genetic comparison that roughly half the immature turtles feeding there came from beaches of Florida, Georgia and South Carolina.

Apparently the immature turtles remain in the pelagic system for about 12 – 15 years. Those that enter the Gulf Stream would encounter the North Atlantic gyre, a huge circular current that carries them toward Europe. A branch of the gyre enters the Mediterranean Sea and along with it go these immature turtles.

The navigational ability of the young turtles is essential for their survival during those travels. It can be fatal if they stray beyond the latitudinal extremes of the current.

The current divides as it approaches Portugal. The northern branch continues up past Great Britain and the water temperature falls rapidly. Turtles swept north in that current would soon perish from the cold. Similarly, turtles that drift south of the current risk being swept into the South Atlantic Current and carried far south of their normal range.

Therefore, an ability to recognize the latitudinal extremes of the current and to respond by swimming in an appropriate direction makes all the difference between life and death.

Unfortunately, other hazards now exist. The records show that many of the immature turtles are hooked and perish on the long-lines set out by fishermen. These run out as far as 75 miles and are armed with millions of hooks. The turtles pass these terrible lines all along their route in both the Atlantic Ocean and the Mediterranean Sea.

Therefore, our poor little hatchlings face a triple whammy. As though it weren't tough enough getting by the predators on our beach just to reach the water, now they must run the gauntlet of long-lines in their travels, as well as the nets of the flotilla of trawlers off our beach upon their return to nest.



Hatching Time


It always seems somehow miraculous that little turtle hatchlings are able to make their way up through about 15 or more inches of packed beach sand and escape the nest for their journey to the sea. Dr. Archie Carr, the grand old man of sea turtle conservation and research, described the process in an amusing way in his book about sea turtles, rather cryptically entitled “So Excellent a Fishe”.

During his studies in Costa Rica, he and his staff relocated a nest with a glass panel fitted into one side. At hatching, he reports as follows what they observed:
"The first young that hatch do not start digging at once but lie still until some of their nest-mates are free of the egg. Each new hatchling adds to the working space, because the spherical eggs and the spaces between them make a volume greater than that of the young and the crumpled shells. The vertical displacement that will carry the turtles to the surface is the upward migration of this chamber, brought about by the witless collaboration that is really a loose sort of division of labor. Although the movements involved are only a generalized thrashing, similar to those that free the hatchling from the egg, they accomplish four different and indispensable things, depending on the position of the turtle in the mass. Turtles of the top layer scratch down the ceiling. Those around the sides undercut the walls. Those on the bottom have two roles, one mechanical and the other psychological: they trample and compact the sand that filters down from above, and they serve as a sort of nervous system for the hatchling superorganism, stirring it out of recurrent spells of lassitude. Lying passively for a time under the weight of its fellows, one of them will suddenly burst into a spasm of squirming that triggers a new pandemic of work in the mass. Thus, by fits and starts, the ceiling falls, the floor rises, and the roomful of collaborating hatchlings is carried toward the surface.

"The turtle siblings thus appear to operate as a survival group; a group, the members of which, by instinctive, generalized, and wholly non-altruistic actions help one another to survive. The little survival band is not trained or prompted by any coach, nor does it consciously work toward any common end. It is just a lot of baby turtles getting restless and becoming annoyed with one another, but in useful ways. Their petulance at being crowded, jostled, and trod upon makes them flail about aimlessly. It is the aimless flailing that takes them steadily up to the surface of the ground."

 

Marvelous Navigation


The lives of marine turtles involve a continual series of migrations. Hatchlings swim directly from their natal beaches into currents such as the Gulf Stream off our own coast. These serve as moving, open-ocean nursery grounds.

Later, the juveniles collect in coastal feeding areas that are hundreds or thousands of kilometers from the beaches where they hatched. And yet, when they become adult and are ready to reproduce, they have the ability to return to their regional beaches.
Green turtles nest on tiny Ascension Island situated in the Atlantic Ocean and far from the African coast. They regularly migrate from their Brazilian feeding grounds directly back to that tiny island to nest.

Kemp's Ridley turtles scattered along our Atlantic coast and in the Gulf of Mexico, converge to nest on a single beach on the east coast of Mexico.

Loggerheads that hatch on beaches in Japan traverse the entire Pacific Ocean to the Baja Peninsula in Mexico before returning to Japan as adults to nest on the regional beaches.

Thus, the picture that emerges is that no stereotypical migratory pathway exists for the adults of a given species or even the population of a specific rookery. Instead, turtles converge on nesting beaches from widely dispersed feeding grounds, and each individual migrates back to its own feeding grounds after nesting is completed.

Satellite tracking of these migrating turtles show that they take a direct route to their destination. These tracked plots leave little doubt that the turtles know where they are going and that they must possess some navigational system to determine their geographic position relative to that goal.

The ability of the turtles to find their way has long intrigued marine biologists. Now it is believed that they must be sensitive to the earth’s magnetic fields. Working with hatchlings has proven to be experimentally easier than with the free-ranging adults for establishing their response to magnetic fields.

Therefore, technically sophisticated experiments were performed in Florida that involved changing the magnetic field in the vicinity of free-swimming hatchlings. It was observed that the hatchlings changed their direction of swimming to match changes both in magnetic field direction and inclination.

Difficult as it may be to believe, these so-called ‘lower’ animals apparently are aware of sensations that totally elude us more ‘advanced’ humans. It would appear that the Animal Kingdom had acquired the Global Positioning System long before Homo sapiens came along.

Range and Population Estimates

The loggerhead turtle nests farther from the tropics than any other marine turtle and is found in temperate and subtropical waters in many parts of the world. Loggerheads forage along the inshore and coastal waters of the Gulf of Mexico, the Florida Keys and north along the eastern seaboard as far as New England. Thousands of young adult loggerhead turtles forage on horseshoe crabs in the river mouths and deeper channels of Chesapeake Bay during the summer months.' During the nesting season adult females remain in shallow areas near their nesting beaches. At other times loggerheads can range hundreds of kilometers out to sea.

The southeastern U.S. is one of the most important nesting areas in the world for this species. An estimated 14,000 female loggerheads nest in the southeastern U.S. annually, and only the population of Masirah Island, Oman, in the Middle East exceeds that of the southeastern U.S. The majority of sea turtles that nest on the mainland of the United States are loggerheads.

Important nesting sites are found on the coastal islands of North and South Carolina and Georgia but most nesting occurs along the mainland coasts in Florida. In Florida, most loggerheads nest from Volusia to Broward counties on the east coast, and some nesting occurs from Monroe to Pinellas counties on the west coast.
Powerful jaws crush mollusks, crabs and encrusting animals attached to reefs and rocks
An estimated 14,000 females nest in the southeastern U.S. each year
A large turtle: Adults weight 200 - 350 pounds and measure about 3 feet in length
Hatchlings: 2 inches long
Nest in Florida from late April to September
Survival in Florida threatened by drowning in shrimp trawls and habitat loss

After nesting in Florida from late April to September, loggerheads disperse to feeding grounds throughout the Bahamas, Cuba, the Dominican Republic, north along the eastern U.S. coast as far as New Jersey during the warmer months, and south through the Florida Keys and the Gulf of Mexico. A loggerhead tagged at Melbourne Beach was recaptured 11 days later on the northwest coast of Cuba. To make this journey the turtle must have traveled at least 70 kilometers (40 miles) a day, often against powerful ocean currents. Another loggerhead that nested at Melbourne Beach was recaptured less than 10 months later 1,500 kilometers (almost 1,000 miles) away in the Dominican Republic. It is not known why turtles travel so far to nest in Florida when seemingly suitable nesting beaches are available near their feeding grounds.



 

 

 

 

 

 

 


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