Sea turtle
Encyclopedia
Sea turtles are marine reptile
s that inhabit all of the world's oceans except the Arctic
.
.
Sea turtles are almost always submerged, and, therefore, have developed an anaerobic
system of respiration. Although all sea turtles breathe air, under dire circumstances they may divert to anaerobic respiration for long periods of time. When surfacing to breathe, a sea turtle can quickly refill its lungs with a single explosive exhalation and rapid inhalation. Their large lungs have adapted to permit rapid exchange of oxygen and to avoid trapping gases during deep dives. However, sea turtles must emerge while breeding, given the extra level of activity.
According to SeaWorld Parks & Entertainment
, a lifespan of 80 years is feasible for sea turtles.
It takes decades for sea turtles to reach sexual maturity. After mating at sea, adult female sea turtles return to land to nest at night. Different species of sea turtles exhibit various levels of philopatry
. In the extreme case, females return to the beach where they hatched. This can take place every two to four years in maturity. They make from one to eight nests per season.
The mature nesting female hauls herself onto the beach, nearly always at night, and finds suitable sand on which to create a nest. Using her hind flippers, she digs a circular hole 40 to 50 cm (15.7 to 19.7 in) deep. After the hole is dug, the female then starts filling the nest with a clutch of soft-shelled eggs one by one until she has deposited around 50 to 200 eggs, depending on the species. Some species have been reported to lay 250 eggs, such as the hawksbill. After laying, she re-fills the nest with sand, re-sculpting and smoothing the surface until it is relatively undetectable visually. The whole process takes thirty to sixty minutes. She then returns to the ocean, leaving the eggs untended.
The hatchling's gender depends on the sand temperature. Lighter sands maintain higher temperatures, which decreases incubation time and results in more female hatchlings.
Incubation takes about two months. The eggs in one nest hatch together over a very short period of time. When ready, hatchlings tear their shells apart with their snout and dig through the sand. Again, this usually takes place at night. Once they reach the surface, they instinctively head towards the sea. If, as happens on rare occasions, hatching takes place during daylight, only a very small proportion of each hatch (usually 0.01%) succeed, because local opportunist predators, such as the common seagull, gorge on the new sea turtles. Thus there is an obvious evolutionary drive to hatch at night, when survival rates on the beach are much higher.
The hatchlings then proceed into the ocean, where a variety of marine predators await them. In 1987, Carr discovered that the young of Chelonia mydas and Caretta caretta spent a great deal of their pelagic lives in floating sargassum
beds, where there are thick mats of unanchored seaweed
. Within these beds, they found ample shelter and food. In the absence of sargassum beds, sea turtle young feed in the vicinity of upwelling
"fronts". In 2007, Reich determined that green sea turtle
hatchlings spend the first three to five years of their lives in pelagic waters. In the open ocean, pre-juveniles of this particular species were found to feed on zooplankton
and smaller nekton
before they are recruited into inshore seagrass meadows as obligate herbivores.
Instead of nesting individually like the other species, Ridley sea turtles come ashore en masse, known as an "arribada" (arrival). With the Kemp's ridley sea turtles this occurs during the day.
Marine sea turtles are caught worldwide, although it is illegal to hunt most species in many countries. A great deal of intentional marine sea turtle harvests worldwide are for food.
Many parts of the world have long considered sea turtles to be fine dining. Ancient Chinese texts dating to the fifth century B.C. describe sea turtles as exotic delicacies. Many coastal communities around the world depend on sea turtles as a source of protein, often harvesting several sea turtles at once and keeping them alive on their backs until needed. Coastal peoples gather sea turtle eggs for consumption.
Sea turtles are popular in Mexico
as boot material and food.
To a much lesser extent, specific species of marine sea turtles are targeted not for their flesh, but for their shells. Tortoiseshell
, a traditional decorative ornamental material used in Japan and China, comes from the carapace
scutes of the hawksbill sea turtle. Ancient Greek
s and ancient Romans processed sea turtle scutes (primarily from the hawksbill) for various articles and ornaments used by their elites, such as combs and brushes. The skin of the flippers is prized for use as shoes and assorted leather goods.
The Moche
people of ancient Peru
worshipped the sea and its animals. They often depicted sea turtles in their art.
Sea turtles enjoy immunity from the sting of the deadly box jellyfish
and regularly eat them, helping keep tropical beaches safe for humans.
Sea turtles, especially green sea turtles, are one of the few animals that eat sea grass. Sea grass needs to be constantly cut short to help it grow across the sea floor. Sea turtles act as grazing animals that cut the grass short and help maintain the health of the sea grass beds. Sea grass beds provide breeding and developmental grounds for numerous species of fish, shellfish and crustaceans. Without sea grass beds, many marine species humans harvest would be lost, as would the lower levels of the food chain. The reactions could result in many more marine species eventually becoming endangered or extinct.
Beaches and dune systems do not get many nutrients. Sea turtles use beaches and the lower dunes to nest and lay their eggs. Sea turtles lay around 100 eggs in a nest and make between 3 and 7 nests during the summer nesting season. Along a 20-mile stretch of beach on the east coast of Florida sea turtles lay over 150,000 lbs of eggs in the sand. Dune vegetation is able to grow and become stronger with the presence of nutrients from sea turtle eggs, unhatched nests, eggs and trapped hatchlings. As the dune vegetation grows stronger and healthier, the health of the entire beach/dune ecosystem becomes better. Stronger vegetation and root systems help to hold the sand in the dunes and help protect the beach from erosion.
Beach towns, such as Tortuguero, Costa Rica, have transitioned from a tourism industry that made profits from selling sea turtle meat and shells to an ecotourism-based economy. Tortuguero is considered to be the founding location of sea turtle conservation. In the 1960s the cultural demand for sea turtle meat, shells, and eggs was quickly killing the once abundant sea turtle populations that nested on the beach. The Caribbean Conservation Corporation began working with villagers to promote ecotourism as a permanent substitute to sea turtle hunting. Sea turtle nesting grounds became sustainable. Since the creation of a sea turtle, ecotourism-based economy, Tortugero annually houses thousands of tourists who visit the protected 22-mile beach that hosts sea turtle walks and nesting grounds.
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All species of sea turtles are listed as threatened or endangered. The leatherback
, Kemp's Ridley
, and hawksbill sea turtles are critically endangered. The Olive Ridley
and green sea turtles are endangered, and the loggerhead is threatened. The flatback's conservation status is unclear due to lack of data.
One of the most significant threats now comes from bycatch
due to imprecise fishing methods. Long-lining has been identified as a major cause of accidental sea turtle death. There is also black-market demand for tortoiseshell for both decoration and supposed health benefits.
Sea turtles must surface to breathe. Caught in a fisherman's net, they are unable to surface and thus drown. In early 2007, almost a thousand sea turtles were killed inadvertently in the Bay of Bengal
over the course of a few months after netting.
However, some relatively inexpensive changes to fishing techniques, such as slightly larger hooks and traps from which sea turtles can escape, can dramatically cut the mortality rate. Turtle Excluder Device
s (TEDs) have reduced sea turtle bycatch in shrimp nets by 97 percent. Another danger comes from marine debris
, especially from abandoned fishing nets
in which they can become entangled.
Beach development is another area which threatens sea turtles. Since many sea turtles return to the same beach each time to nest, development can disrupt the cycle. There has been a movement to protect these areas, in some cases by special police. In some areas, such as the east coast of Florida
, conservationists dig up sea turtle eggs and relocate them to fenced nurseries to protect them from beach traffic.
Since hatchlings find their way to the ocean by crawling towards the brightest horizon, they can become disoriented on developed stretches of coastline. Lighting restrictions can prevent lights from shining on the beach and confusing hatchlings. Sea turtle-safe lighting uses red or amber LED light, invisible to sea turtles, in place of white light.
Another major threat to sea turtles is black-market trade in eggs and meat. This is a problem throughout the world, but especially a concern in the Philippines
, India
, Indonesia
and the coastal nations of Latin America
. Estimates reach as high as 35,000 sea turtles killed a year in Mexico
and the same number in Nicaragua
. Conservationists in Mexico and the United States have launched "Don't Eat Sea Turtle" campaigns in order to reduce this trade in sea turtle products. These campaigns have involved figures such as Dorismar, Los Tigres del Norte
and Maná
. Sea turtles are often consumed during the Catholic season of Lent, even though they are reptiles, not fish. Consequently, conservation organizations have written letters to the Pope asking that he declare sea turtles meat.
Climate change may also cause a threat to sea turtles. Since sand temperature at nesting beaches defines the sex of a sea turtle while developing in the egg, there is concern that rising temperatures may produce too many females. However, more research is needed to understand how climate change might affect sea turtle gender distribution and what other possible threats it may pose.
Fibropapillomatosis
disease causes tumors in sea turtles.
Injured sea turtles are sometimes rescued and rehabilitated by professional organizations, such as The Loggerhead Marinelife Center in Juno Beach, FL, The Turtle Hospital in Marathon, Florida, the Mote Marine Laboratory
in Sarasota, Florida, the Marine Mammal Center in Northern California, the Clearwater Marine Aquarium
in Clearwater, Florida, and the Sea Turtle Inc. organization in South Padre Island, Texas
. One such sea turtle, named Nickel for the coin that was found lodged in her throat, lives at the Shedd Aquarium
in Chicago
.
In the Caribbean, researchers are having some success in assisting a comeback. In September 2007, Corpus Christi, Texas
, wildlife
officials found 128 Kemp's ridley sea turtle nest
s on Texas beaches, a record number, including 81 on North Padre Island
(Padre Island National Seashore
) and four on Mustang Island
. Wildlife officials released 10,594 Kemp's ridleys hatchlings along the Texas coast
this year.
Also in 2007, the U.S. Fish and Wildlife Service and the National Marine Fisheries Service
issued a determination that the leatherback, the hawksbill and the Kemp's Ridley populations were endangered while that of green sea turtles and olive ridleys were threatened.
In Southeast Asia
, the Philippines
has had several initiatives dealing with the issue of sea turtle conservation. In 2007, the province of Batangas
in the Philippines
declared the catching and eating of Pawikans illegal. However, the law seems to have had little effect as Pawikan eggs are still in demand in Batangan markets. In September 2007, several Chinese
poachers
were apprehended off the Turtle Islands
in the country's southernmost province of Tawi-Tawi
. The poachers had collected more than a hundred sea turtles, along with 10,000 sea turtle eggs.
Evaluating the progress of conservation programs is difficult, because many sea turtle populations have not been assessed adequately. Most information on sea turtle populations comes from counting nests on beaches, but this doesn’t provide an accurate picture of the whole sea turtle population. A 2010 United States National Research Council report concluded that more detailed information on sea turtles’ life cycles, such as birth rates and mortality, is needed.
Sea turtles are very vulnerable to oil pollution, both because of their tendency to linger on the water's surface, and because oil can effect them at every stage of their life cycle. Oil can poison the sea turtles upon entering their digestive system.
Sea turtles play key roles in two ecosystem types that are critical to them as well as to humans—oceans and beaches/dunes. In the oceans, for example, sea turtles, especially green sea turtles, are one of very few creatures (manatees are another) that eat the sea grass that grows on the sea floor. Sea grass must be kept short to remain healthy, and beds of healthy sea grass are essential breeding and development areas for many species of fish and other marine life. A decline or loss of sea grass beds would damage these populations, triggering a chain reaction and negatively impacting marine and human life.
Beaches and dunes form a fragile ecosystem that depends on vegetation to protect against erosion. Eggs, hatched or unhatched, and hatchlings that fail to make it into the ocean are nutrient sources for dune vegetation . Every year, sea turtles lay countless eggs on beaches. Along one twenty-mile (32 km) stretch of beach in Florida alone, for example, more than 150,000 pounds of eggs are laid each year.
Sea turtles, along with other turtles and tortoises, are part of the order Testudines.
The seven living species of sea turtles are: flatback sea turtle, green sea turtle
, hawksbill sea turtle, Kemp's ridley sea turtle, leatherback sea turtle
, loggerhead sea turtle
and olive ridley sea turtle. All species except the leatherback are in the family Cheloniidae. The leatherback belongs to the family Dermochelyidae and is its only member.
The species are primarily distinguished by their anatomy: for instance, the prefrontal scales on the head, the number of and shape of scutes on the carapace
, and the type of inframarginal scutes on the plastron. The leatherback
is the only sea turtle that does not have a hard shell; instead, it bears a mosaic of bony plates beneath its leathery skin. It is the largest sea turtle, measuring 6 to 7 ft (1.8 to 2.1 m) in length at maturity, and 3 to 5 ft (0.9144 to 1.5 m) in width, weighing up to 1300 pounds (589.7 kg). Other species are smaller, being mostly 2 to 4 ft (0.6096 to 1.2 m) and proportionally narrower.
Sea turtles constitute a single radiation that became distinct from all other turtles at least 110 million years ago.
From SWOT Report, vol. 1:
showing the phylogenetic relationships of living and extinct sea turtles in the family Cheloniidae based on Lynch and Parham (2003) and Parham and Pyenson (2010).
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...
s that inhabit all of the world's oceans except the Arctic
Arctic Ocean
The Arctic Ocean, located in the Northern Hemisphere and mostly in the Arctic north polar region, is the smallest and shallowest of the world's five major oceanic divisions...
.
Distribution
The superfamily Chelonioidea has a world-wide distribution; sea turtles can be found in all oceans except for the polar regions. Some species travel between oceans. The flatback sea turtle is found solely on the northern coast of AustraliaAustralia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
.
Respiration
Anaerobic respiration
Anaerobic respiration is a form of respiration using electron acceptors other than oxygen. Although oxygen is not used as the final electron acceptor, the process still uses a respiratory electron transport chain; it is respiration without oxygen...
system of respiration. Although all sea turtles breathe air, under dire circumstances they may divert to anaerobic respiration for long periods of time. When surfacing to breathe, a sea turtle can quickly refill its lungs with a single explosive exhalation and rapid inhalation. Their large lungs have adapted to permit rapid exchange of oxygen and to avoid trapping gases during deep dives. However, sea turtles must emerge while breeding, given the extra level of activity.
Life history
SeaWorld Parks & Entertainment
SeaWorld Parks & Entertainment is a family entertainment company owned by The Blackstone Group. SeaWorld is responsible for the operation and maintenance of eleven theme parks located throughout the United States...
, a lifespan of 80 years is feasible for sea turtles.
It takes decades for sea turtles to reach sexual maturity. After mating at sea, adult female sea turtles return to land to nest at night. Different species of sea turtles exhibit various levels of philopatry
Philopatry
Broadly, philopatry is the behaviour of remaining in, or returning to, an individual's birthplace. More specifically, in ecology philopatry is the behaviour of elder offspring sharing the parental burden in the upbringing of their siblings, a classic example of kin selection...
. In the extreme case, females return to the beach where they hatched. This can take place every two to four years in maturity. They make from one to eight nests per season.
The mature nesting female hauls herself onto the beach, nearly always at night, and finds suitable sand on which to create a nest. Using her hind flippers, she digs a circular hole 40 to 50 cm (15.7 to 19.7 in) deep. After the hole is dug, the female then starts filling the nest with a clutch of soft-shelled eggs one by one until she has deposited around 50 to 200 eggs, depending on the species. Some species have been reported to lay 250 eggs, such as the hawksbill. After laying, she re-fills the nest with sand, re-sculpting and smoothing the surface until it is relatively undetectable visually. The whole process takes thirty to sixty minutes. She then returns to the ocean, leaving the eggs untended.
The hatchling's gender depends on the sand temperature. Lighter sands maintain higher temperatures, which decreases incubation time and results in more female hatchlings.
The hatchlings then proceed into the ocean, where a variety of marine predators await them. In 1987, Carr discovered that the young of Chelonia mydas and Caretta caretta spent a great deal of their pelagic lives in floating sargassum
Sargassum
Sargassum is a genus of brown macroalga in the order Fucales. Numerous species are distributed throughout the temperate and tropical oceans of the world, where they generally inhabit shallow water and coral reefs. However, the genus may be best known for its planktonic species...
beds, where there are thick mats of unanchored seaweed
Seaweed
Seaweed is a loose, colloquial term encompassing macroscopic, multicellular, benthic marine algae. The term includes some members of the red, brown and green algae...
. Within these beds, they found ample shelter and food. In the absence of sargassum beds, sea turtle young feed in the vicinity of upwelling
Upwelling
Upwelling is an oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water towards the ocean surface, replacing the warmer, usually nutrient-depleted surface water. The increased availability in upwelling regions results in high levels of primary...
"fronts". In 2007, Reich determined that green sea turtle
Green Sea Turtle
The Green sea turtle or green turtle is a large sea turtle of the family Cheloniidae. It is the only species in the genus Chelonia. Its range extends throughout tropical and subtropical seas around the world, with two distinct populations in the Atlantic and Pacific Oceans...
hatchlings spend the first three to five years of their lives in pelagic waters. In the open ocean, pre-juveniles of this particular species were found to feed on zooplankton
Zooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...
and smaller nekton
Nekton
Nekton refers to the aggregate of actively swimming aquatic organisms in a body of water able to move independently of water currents....
before they are recruited into inshore seagrass meadows as obligate herbivores.
Instead of nesting individually like the other species, Ridley sea turtles come ashore en masse, known as an "arribada" (arrival). With the Kemp's ridley sea turtles this occurs during the day.
Salt gland
Sea turtles possess a salt excretory gland at the corner of the eye, in the nostrils, or in the tongue, depending on the species; chelonian salt glands are found in the corner of the eyes in leatherback sea turtles. Due to the iso-osmotic makeup of jellyfish and the other gelatinous prey upon which sea turtles subsist, sea turtle diets are high in salt; chelonian salt gland excretions are almost entirely composed of sodium chloride 1500-1800 mosmoll-1 (Marshall and Cooper, 1988; Nicolson and Lutz, 1989; Reina and Cooper, 2000).Importance to humans
Many parts of the world have long considered sea turtles to be fine dining. Ancient Chinese texts dating to the fifth century B.C. describe sea turtles as exotic delicacies. Many coastal communities around the world depend on sea turtles as a source of protein, often harvesting several sea turtles at once and keeping them alive on their backs until needed. Coastal peoples gather sea turtle eggs for consumption.
Sea turtles are popular in Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
as boot material and food.
To a much lesser extent, specific species of marine sea turtles are targeted not for their flesh, but for their shells. Tortoiseshell
Tortoiseshell material
Tortoiseshell or tortoise shell is a material produced mainly from the shell of the hawksbill turtle, an endangered species. It was widely used in the 1960s and 1970s in the manufacture of items such as combs, sunglasses, guitar picks and knitting needles...
, a traditional decorative ornamental material used in Japan and China, comes from the carapace
Carapace
A carapace is a dorsal section of the exoskeleton or shell in a number of animal groups, including arthropods such as crustaceans and arachnids, as well as vertebrates such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron.-Crustaceans:In crustaceans, the...
scutes of the hawksbill sea turtle. Ancient Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
s and ancient Romans processed sea turtle scutes (primarily from the hawksbill) for various articles and ornaments used by their elites, such as combs and brushes. The skin of the flippers is prized for use as shoes and assorted leather goods.
The Moche
Moche
'The Moche civilization flourished in northern Peru from about 100 AD to 800 AD, during the Regional Development Epoch. While this issue is the subject of some debate, many scholars contend that the Moche were not politically organized as a monolithic empire or state...
people of ancient Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
worshipped the sea and its animals. They often depicted sea turtles in their art.
Sea turtles enjoy immunity from the sting of the deadly box jellyfish
Box jellyfish
Box jellyfish are cnidarian invertebrates distinguished by their cube-shaped medusae. Box jellyfish are known for the extremely potent venom produced by some species: Chironex fleckeri, Carukia barnesi and Malo kingi are among the most venomous creatures in the world...
and regularly eat them, helping keep tropical beaches safe for humans.
Sea turtles, especially green sea turtles, are one of the few animals that eat sea grass. Sea grass needs to be constantly cut short to help it grow across the sea floor. Sea turtles act as grazing animals that cut the grass short and help maintain the health of the sea grass beds. Sea grass beds provide breeding and developmental grounds for numerous species of fish, shellfish and crustaceans. Without sea grass beds, many marine species humans harvest would be lost, as would the lower levels of the food chain. The reactions could result in many more marine species eventually becoming endangered or extinct.
Beaches and dune systems do not get many nutrients. Sea turtles use beaches and the lower dunes to nest and lay their eggs. Sea turtles lay around 100 eggs in a nest and make between 3 and 7 nests during the summer nesting season. Along a 20-mile stretch of beach on the east coast of Florida sea turtles lay over 150,000 lbs of eggs in the sand. Dune vegetation is able to grow and become stronger with the presence of nutrients from sea turtle eggs, unhatched nests, eggs and trapped hatchlings. As the dune vegetation grows stronger and healthier, the health of the entire beach/dune ecosystem becomes better. Stronger vegetation and root systems help to hold the sand in the dunes and help protect the beach from erosion.
Beach towns, such as Tortuguero, Costa Rica, have transitioned from a tourism industry that made profits from selling sea turtle meat and shells to an ecotourism-based economy. Tortuguero is considered to be the founding location of sea turtle conservation. In the 1960s the cultural demand for sea turtle meat, shells, and eggs was quickly killing the once abundant sea turtle populations that nested on the beach. The Caribbean Conservation Corporation began working with villagers to promote ecotourism as a permanent substitute to sea turtle hunting. Sea turtle nesting grounds became sustainable. Since the creation of a sea turtle, ecotourism-based economy, Tortugero annually houses thousands of tourists who visit the protected 22-mile beach that hosts sea turtle walks and nesting grounds.
Conservation
Leatherback Sea Turtle
The leatherback sea turtle is the largest of all living sea turtles and the fourth largest modern reptile behind three crocodilians. It is the only living species in the genus Dermochelys. It can easily be differentiated from other modern sea turtles by its lack of a bony shell. Instead, its...
, Kemp's Ridley
Kemp's Ridley
Kemp's ridley sea turtle , or Atlantic ridley sea turtle is the rarest sea turtle and is critically endangered. It is one of two living species in the genus Lepidochelys Kemp's ridley sea turtle (Lepidochelys kempii), or Atlantic ridley sea turtle is the rarest sea turtle and is critically...
, and hawksbill sea turtles are critically endangered. The Olive Ridley
Olive Ridley
The olive ridley sea turtle , also known as the Pacific ridley, is a species of sea turtle.- Description :The olive ridley is a small extant sea turtle, with an adult carapace length averaging 60 to 70 cm 1...
and green sea turtles are endangered, and the loggerhead is threatened. The flatback's conservation status is unclear due to lack of data.
One of the most significant threats now comes from bycatch
Bycatch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
due to imprecise fishing methods. Long-lining has been identified as a major cause of accidental sea turtle death. There is also black-market demand for tortoiseshell for both decoration and supposed health benefits.
Sea turtles must surface to breathe. Caught in a fisherman's net, they are unable to surface and thus drown. In early 2007, almost a thousand sea turtles were killed inadvertently in the Bay of Bengal
Bay of Bengal
The Bay of Bengal , the largest bay in the world, forms the northeastern part of the Indian Ocean. It resembles a triangle in shape, and is bordered mostly by the Eastern Coast of India, southern coast of Bangladesh and Sri Lanka to the west and Burma and the Andaman and Nicobar Islands to the...
over the course of a few months after netting.
However, some relatively inexpensive changes to fishing techniques, such as slightly larger hooks and traps from which sea turtles can escape, can dramatically cut the mortality rate. Turtle Excluder Device
Turtle excluder device
A turtle excluder device or TED is a specialized device that allows a captured sea turtle to escape when caught in a fisherman's net.In particular, sea turtles can be caught when bottom trawling is used by the commercial shrimp fishing industry. In order to catch shrimp, a fine meshed trawl net is...
s (TEDs) have reduced sea turtle bycatch in shrimp nets by 97 percent. Another danger comes from marine debris
Marine debris
Marine debris, also known as marine litter, is human created waste that has deliberately or accidentally become afloat in a lake, sea, ocean or waterway. Oceanic debris tends to accumulate at the centre of gyres and on coastlines, frequently washing aground, when it is known as beach litter or...
, especially from abandoned fishing nets
Ghost net
Ghost nets are fishing nets that have been left or lost in the ocean by fishermen. These nets, often nearly invisible in the dim light, can be left tangled on a rocky reef or drifting in the open sea. They can entangle fish, dolphins, sea turtles, sharks, dugongs, crocodiles, seabirds, crabs, and...
in which they can become entangled.
Beach development is another area which threatens sea turtles. Since many sea turtles return to the same beach each time to nest, development can disrupt the cycle. There has been a movement to protect these areas, in some cases by special police. In some areas, such as the east coast of Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
, conservationists dig up sea turtle eggs and relocate them to fenced nurseries to protect them from beach traffic.
Since hatchlings find their way to the ocean by crawling towards the brightest horizon, they can become disoriented on developed stretches of coastline. Lighting restrictions can prevent lights from shining on the beach and confusing hatchlings. Sea turtle-safe lighting uses red or amber LED light, invisible to sea turtles, in place of white light.
Another major threat to sea turtles is black-market trade in eggs and meat. This is a problem throughout the world, but especially a concern in the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
, Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
and the coastal nations of Latin America
Latin America
Latin America is a region of the Americas where Romance languages – particularly Spanish and Portuguese, and variably French – are primarily spoken. Latin America has an area of approximately 21,069,500 km² , almost 3.9% of the Earth's surface or 14.1% of its land surface area...
. Estimates reach as high as 35,000 sea turtles killed a year in Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
and the same number in Nicaragua
Nicaragua
Nicaragua is the largest country in the Central American American isthmus, bordered by Honduras to the north and Costa Rica to the south. The country is situated between 11 and 14 degrees north of the Equator in the Northern Hemisphere, which places it entirely within the tropics. The Pacific Ocean...
. Conservationists in Mexico and the United States have launched "Don't Eat Sea Turtle" campaigns in order to reduce this trade in sea turtle products. These campaigns have involved figures such as Dorismar, Los Tigres del Norte
Los Tigres del Norte
Los Tigres del Norte is a norteño-band ensemble based out of San Jose, California, hailing from Rosa Morada, Sinaloa, Mexico.- History :...
and Maná
Maná
Maná is a pop rock band from Guadalajara, Jalisco, Mexico, whose career has spanned more than three decades. They have earned three Grammy Awards, seven Latin Grammy Awards, five MTV Video Music Awards Latin America, five Premios Juventud awards, nine Billboard Latin Music Awards and 13 Premios Lo...
. Sea turtles are often consumed during the Catholic season of Lent, even though they are reptiles, not fish. Consequently, conservation organizations have written letters to the Pope asking that he declare sea turtles meat.
Fibropapillomatosis
Fibropapillomatosis
Fibropapillomatosis is a condition characterized by the presence of fibropapillomas, neoplasms consisting of both the epidermal and dermal skin layers.-In sea turtles:...
disease causes tumors in sea turtles.
Injured sea turtles are sometimes rescued and rehabilitated by professional organizations, such as The Loggerhead Marinelife Center in Juno Beach, FL, The Turtle Hospital in Marathon, Florida, the Mote Marine Laboratory
Mote Marine Laboratory
Mote Marine Laboratory is an independent not-for-profit marine research organization based on City Island in Sarasota, FL. The laboratory aims to advance the science of the sea, both through its marine and estuarine research labs and through the public Mote Aquarium and its affiliated educational...
in Sarasota, Florida, the Marine Mammal Center in Northern California, the Clearwater Marine Aquarium
Clearwater Marine Aquarium
The Clearwater Marine Aquarium is a non-profit organization in Clearwater, Florida dedicated to the rescue, rehabilitation and release of injured marine animals, public education, animal-assisted therapy and research....
in Clearwater, Florida, and the Sea Turtle Inc. organization in South Padre Island, Texas
South Padre Island, Texas
South Padre Island is a town in Cameron County, Texas, United States. It is part of the Brownsville–Harlingen Metropolitan Statistical Area. It may be included as part of the Brownsville–Harlingen–Raymondville and the Matamoros–Brownsville metropolitan areas. The population was 2,816 at the...
. One such sea turtle, named Nickel for the coin that was found lodged in her throat, lives at the Shedd Aquarium
Shedd Aquarium
The John G. Shedd Aquarium is an indoor public aquarium in Chicago, Illinois in the United States that opened on May 30, 1930. The aquarium contains over 25,000 fish, and was for some time the largest indoor aquarium in the world with of water. The Shedd Aquarium was the first inland aquarium with...
in Chicago
Chicago
Chicago is the largest city in the US state of Illinois. With nearly 2.7 million residents, it is the most populous city in the Midwestern United States and the third most populous in the US, after New York City and Los Angeles...
.
In the Caribbean, researchers are having some success in assisting a comeback. In September 2007, Corpus Christi, Texas
Corpus Christi, Texas
Corpus Christi is a coastal city in the South Texas region of the U.S. state of Texas. The county seat of Nueces County, it also extends into Aransas, Kleberg, and San Patricio counties. The MSA population in 2008 was 416,376. The population was 305,215 at the 2010 census making it the...
, wildlife
Wildlife
Wildlife includes all non-domesticated plants, animals and other organisms. Domesticating wild plant and animal species for human benefit has occurred many times all over the planet, and has a major impact on the environment, both positive and negative....
officials found 128 Kemp's ridley sea turtle nest
Nest
A nest is a place of refuge to hold an animal's eggs or provide a place to live or raise offspring. They are usually made of some organic material such as twigs, grass, and leaves; or may simply be a depression in the ground, or a hole in a tree, rock or building...
s on Texas beaches, a record number, including 81 on North Padre Island
Padre Island
Padre Island is part of the U.S. state of Texas. The island is located on Texas' southern coast of the Gulf of Mexico and is famous for its white sandy beaches at the south end...
(Padre Island National Seashore
Padre Island National Seashore
Padre Island National Seashore is a National Seashore located on Padre Island off the coast of South Texas. In contrast to South Padre Island , PINS is located on North Padre Island and consists of a long beach where nature is preserved...
) and four on Mustang Island
Mustang Island
Mustang Island is a barrier island on the Gulf Coast of Texas in the United States. The island is 18 miles long, stretching from Corpus Christi to Port Aransas. The island is oriented generally northeast-southwest, with the Gulf of Mexico on the east and south, and Corpus Christi Bay on the north...
. Wildlife officials released 10,594 Kemp's ridleys hatchlings along the Texas coast
Coast
A coastline or seashore is the area where land meets the sea or ocean. A precise line that can be called a coastline cannot be determined due to the dynamic nature of tides. The term "coastal zone" can be used instead, which is a spatial zone where interaction of the sea and land processes occurs...
this year.
Also in 2007, the U.S. Fish and Wildlife Service and the National Marine Fisheries Service
National Marine Fisheries Service
The National Marine Fisheries Service is a United States federal agency. A division of the National Oceanic and Atmospheric Administration and the Department of Commerce, NMFS is responsible for the stewardship and management of the nation's living marine resources and their habitat within the...
issued a determination that the leatherback, the hawksbill and the Kemp's Ridley populations were endangered while that of green sea turtles and olive ridleys were threatened.
In Southeast Asia
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
, the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
has had several initiatives dealing with the issue of sea turtle conservation. In 2007, the province of Batangas
Batangas
Batangas is a first class province of the Philippines located on the southwestern part of Luzon in the CALABARZON region. Its capital is Batangas City and it is bordered by the provinces of Cavite and Laguna to the north and Quezon to the east. Across the Verde Island Passages to the south is the...
in the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
declared the catching and eating of Pawikans illegal. However, the law seems to have had little effect as Pawikan eggs are still in demand in Batangan markets. In September 2007, several Chinese
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
poachers
Poaching
Poaching is the illegal taking of wild plants or animals contrary to local and international conservation and wildlife management laws. Violations of hunting laws and regulations are normally punishable by law and, collectively, such violations are known as poaching.It may be illegal and in...
were apprehended off the Turtle Islands
Turtle Islands, Tawi-Tawi
Turtle Islands, also known as Turtle Isles, is a 5th class municipality composed of a remote group of seven islands in the province of Tawi-Tawi in the Southern Philippines.-Location:...
in the country's southernmost province of Tawi-Tawi
Tawi-Tawi
Tawi-Tawi is an island province of the Philippines located in the Autonomous Region in Muslim Mindanao . The capital of Tawi-Tawi is Bongao. The province is the southernmost of the country sharing sea borders with the Malaysian State of Sabah and the Indonesian East Kalimantan province. To the...
. The poachers had collected more than a hundred sea turtles, along with 10,000 sea turtle eggs.
Evaluating the progress of conservation programs is difficult, because many sea turtle populations have not been assessed adequately. Most information on sea turtle populations comes from counting nests on beaches, but this doesn’t provide an accurate picture of the whole sea turtle population. A 2010 United States National Research Council report concluded that more detailed information on sea turtles’ life cycles, such as birth rates and mortality, is needed.
Sea turtles are very vulnerable to oil pollution, both because of their tendency to linger on the water's surface, and because oil can effect them at every stage of their life cycle. Oil can poison the sea turtles upon entering their digestive system.
Fragile ecosystems
Beaches and dunes form a fragile ecosystem that depends on vegetation to protect against erosion. Eggs, hatched or unhatched, and hatchlings that fail to make it into the ocean are nutrient sources for dune vegetation . Every year, sea turtles lay countless eggs on beaches. Along one twenty-mile (32 km) stretch of beach in Florida alone, for example, more than 150,000 pounds of eggs are laid each year.
Threats to sea turtles
Of the seven species of sea turtles, all are listed on the IUCN Red List of Endangered Species as either "endangered" or "critically endangered". Although sea turtles usually lay around one hundred eggs at a time, on average only one of the eggs from the nest will survive to adulthood. While many of the things that endanger these hatchlings are natural, such as predators including sharks, raccoons, foxes, and seagulls, many new threats to the sea turtle species have recently arrived and increased with the ever-growing presence of humans.Taxonomy and evolution
The seven living species of sea turtles are: flatback sea turtle, green sea turtle
Green Sea Turtle
The Green sea turtle or green turtle is a large sea turtle of the family Cheloniidae. It is the only species in the genus Chelonia. Its range extends throughout tropical and subtropical seas around the world, with two distinct populations in the Atlantic and Pacific Oceans...
, hawksbill sea turtle, Kemp's ridley sea turtle, leatherback sea turtle
Leatherback Sea Turtle
The leatherback sea turtle is the largest of all living sea turtles and the fourth largest modern reptile behind three crocodilians. It is the only living species in the genus Dermochelys. It can easily be differentiated from other modern sea turtles by its lack of a bony shell. Instead, its...
, loggerhead sea turtle
Loggerhead sea turtle
The loggerhead sea turtle , or loggerhead, is an oceanic turtle distributed throughout the world. It is a marine reptile, belonging to the family Cheloniidae. The average loggerhead measures around long when fully grown, although larger specimens of up to have been discovered...
and olive ridley sea turtle. All species except the leatherback are in the family Cheloniidae. The leatherback belongs to the family Dermochelyidae and is its only member.
The species are primarily distinguished by their anatomy: for instance, the prefrontal scales on the head, the number of and shape of scutes on the carapace
Carapace
A carapace is a dorsal section of the exoskeleton or shell in a number of animal groups, including arthropods such as crustaceans and arachnids, as well as vertebrates such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron.-Crustaceans:In crustaceans, the...
, and the type of inframarginal scutes on the plastron. The leatherback
Leatherback Sea Turtle
The leatherback sea turtle is the largest of all living sea turtles and the fourth largest modern reptile behind three crocodilians. It is the only living species in the genus Dermochelys. It can easily be differentiated from other modern sea turtles by its lack of a bony shell. Instead, its...
is the only sea turtle that does not have a hard shell; instead, it bears a mosaic of bony plates beneath its leathery skin. It is the largest sea turtle, measuring 6 to 7 ft (1.8 to 2.1 m) in length at maturity, and 3 to 5 ft (0.9144 to 1.5 m) in width, weighing up to 1300 pounds (589.7 kg). Other species are smaller, being mostly 2 to 4 ft (0.6096 to 1.2 m) and proportionally narrower.
Sea turtles constitute a single radiation that became distinct from all other turtles at least 110 million years ago.
From SWOT Report, vol. 1:
- Family Cheloniidae
- Chelonia mydas or green sea turtleGreen Sea TurtleThe Green sea turtle or green turtle is a large sea turtle of the family Cheloniidae. It is the only species in the genus Chelonia. Its range extends throughout tropical and subtropical seas around the world, with two distinct populations in the Atlantic and Pacific Oceans...
- Eretmochelys imbricata or hawksbill sea turtle
- Natator depressus or flatback sea turtle
- Caretta caretta or Loggerhead sea turtleLoggerhead sea turtleThe loggerhead sea turtle , or loggerhead, is an oceanic turtle distributed throughout the world. It is a marine reptile, belonging to the family Cheloniidae. The average loggerhead measures around long when fully grown, although larger specimens of up to have been discovered...
- Lepidochelys kempii or Kemp's ridley sea turtle
- Lepidochelys olivacea or olive ridley sea turtle
- Chelonia mydas or green sea turtle
- Family Dermochelyidae
- Dermochelys coriacea or leatherback sea turtleLeatherback Sea TurtleThe leatherback sea turtle is the largest of all living sea turtles and the fourth largest modern reptile behind three crocodilians. It is the only living species in the genus Dermochelys. It can easily be differentiated from other modern sea turtles by its lack of a bony shell. Instead, its...
- Dermochelys coriacea or leatherback sea turtle
Cladogram
Below is a cladogramCladogram
A cladogram is a diagram used in cladistics which shows ancestral relations between organisms, to represent the evolutionary tree of life. Although traditionally such cladograms were generated largely on the basis of morphological characters, DNA and RNA sequencing data and computational...
showing the phylogenetic relationships of living and extinct sea turtles in the family Cheloniidae based on Lynch and Parham (2003) and Parham and Pyenson (2010).
See also
- SandwatchSandwatchSandwatch is a grassroots network of schools and community groups working together to monitor and conserve local beach and nearshore environments and to build resilience to climate change...
- Sea Turtle Association of Japan, Kuroshima Research StationSea Turtle Association of Japan, Kuroshima Research StationKuroshima Research Station started in 1973, under the name of the UnderwaterPark Foundation, Yaeyama Underwater Park Research Institute, for the purpose of managing and utilizing the underwater area in Sekisei lagoon between Ishigaki Island and Iriomote Island including Kuroshima Island...
- Sea turtle threats
- Shrimp turtle caseShrimp turtle caseIn 1994, the WTO intervened to address member concerns regarding the import of shrimp and its impact on turtles. This became known as the Shrimp and Turtle case. The ruling was adopted on November 6, 1998. However, Malaysia persisted in their complaint and initiated DSU Article 21.5 proceedings...
- Caribbean Conservation CorporationCaribbean Conservation CorporationThe Sea Turtle Conservancy , formerly known as Caribbean Conservation Corporation is an American not-for-profit 501 membership organization based in Gainesville, Florida. STC was incorporated, based on an earlier informal organization known as The Brotherhood of the Green Turtle, in 1959 by Mr....
Additional reading
- Davidson, Osha Gray. (2001). Fire in the Turtle House: The Green Sea Turtle and the Fate of the Ocean. United States: United States of Public Affairs. ISBN 1-5864-8199-1.
- Spotila, James R. (2004). Sea Turtles: A Complete Guide to Their Biology, Behavior, and Conservation. Baltimore: Johns Hopkins University Press. ISBN 0-8018-8007-6.
- Witherington, Blair E. (2006). Sea Turtles: An Extraordinary Natural History of Some Uncommon Turtles. St. Paul: Voyageur Press. ISBN 0-7603-2644-4.
External links
- Here http://www.youtube.com/watch?v=Ip0fBjpN9F4 you can see the turtles of SipadanSipadanSipadan is the only oceanic island in Malaysia, rising from the seabed. It is located in the Celebes Sea off the east coast of Sabah, East Malaysia . It was formed by living corals growing on top of an extinct volcanic cone that took thousands of years to develop...
. It was filmed by Christoph BrüxChristoph BrüxChristoph Brüx is a German composer, pianist, keyboardist, arranger and music producer.He composed for interpreters such as No Angels, Matthias Reim, The Underdog Project, Brooklyn Bounce etc., and he also composed film scores.... - http://www.wildlifetrust.org/enter.cgi?p=news/2006/1001_3_turtle.shtml Wildlife Trust Sea Turtle protection and research
- Conserving Turtles on a Global Scale
- Underwater video of turtles in the Red Sea, Egypt
- Sea Turtle Research and Conservation - Center for Biodiversity and Conservation, American Museum of Natural History
- Sea Turtle conservation in Costa Rica
- Juara Turtle Project, Tioman, Malaysia