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SEA TURTLE
Introduction
Sea turtles are air-breathing reptiles with streamlined bodies and large flippers. They are
well adapted to life in the ocean and inhabit tropical and subtropical ocean waters around
the world. Although sea turtles live most of their lives in the ocean, adult females have to
return to beaches to lay their eggs. They often migrate long distances between feeding
areas and nesting beaches.
Systematic position of sea turtle
Kingdom: Animalia.
Phylum: Chordata.
Class: Reptilia.
Order: Testudines.
Suborder: Cryptodira.
Clade: Panchelonioidea.
Superfamily: Chelonioidea.
Families; Pancheloniidae, Cheloniidae,
Dermochelyidae, Protostegidae.
Behaviour and habitat
Sea turtles are generally found in the waters over continental shelves. After taking to the
water for the first time, males will not return to shore again. During the first three to five
years of life, sea turtles spend most time in the pelagic zone floating in seaweed beds.
Green sea turtles in particular are often found in Sargassum beds, a brown seaweed in
which they find shelter and food. Once the sea turtle has reached adulthood it moves
closer to the shore. Females will come ashore to lay their eggs on sandy beaches during
the nesting season.
Diet
Sea turtles feed on a wide range of animals and plants. They are mostly omnivorous in
their adult life.
Green sea turtles- commonly found in sea grass meadows closer inshore as herbivorous
grazers.
The flat back turtle -Sea grass, marine invertebrates including molluscs, jellyfish and
shrimp fishes. It also consumes of soft coral, sea cucumbers.
The loggerhead – Bottom dwelling invertebrates, such as gastropods, bivalves, and
decapods. Other food items include sponges, corals, sea pens, polychaete worms, sea

2. anemones, insects, sea urchins, sea cucumbers, starfish, fish, and hatchling turtles
(including members of its own species).
Kemp's ridley- molluscs, crustaceans, jellyfish, algae or seaweed and sea urchins.
The olive ridley- predominantly carnivorous, especially in immature stages of the life
cycle. Animal prey consists of invertebrates.
Adaptations: - Swimming: All species share features such as paddle-shaped limbs
and a streamlined shape with an enlarged shoulder girdle and well-developed pectoral
muscles which aid in swimming. Sea turtles are also excellent divers. Leatherbacks
routinely dive to depths exceeding 1000 feet in search of jellyfish. During long dives,
blood is shunted away from tissues tolerant of low oxygen levels toward the heart, brain,
and central nervous system.
Respiration
Sea turtles are almost always submerged, and therefore, have developed an anaerobic
system of energy metabolism. Although all sea turtles breathe air, under dire
circumstances they may divert to anaerobic metabolism 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.
Metabolism
Sea turtles are known to have a reduced metabolic rate which allows them to stay
underwater for long periods of time before needing to resurface to breathe. They are also
equipped with enlarged lacrimal or tear glands modified to remove excess salts from
body fluids. They are able to live in seawater without the need for a freshwater source as
they can obtain sufficient water from their diet and from metabolising seawater.
Thermoregulation
A sea turtle’s large size leads to a low surface area to volume ratio, so the heat exchange
rate is low compared to total size. The thermoregulatory adaptations of leatherback
turtles in particular, such as a counter-current heat exchange system, high oil content,
and large body size, allow them to maintain a core body temperature higher than that of
the surrounding water (up to 18◦C above their surroundings), thereby allowing them to
tolerate colder water temperatures.
Navigation
The ability of some sea turtles to migrate in the open ocean between feeding and nesting
grounds sometimes separated by thousands of kilometres. Commonly held among the
suggested theories is that when hatchlings emerge, they are “imprinted” on the earth’s
geomagnetic field. Using their ability to differentiate magnetic field intensities and
inclination angles, they are able to migrate back to their natal beaches as adults.
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Life history
Reproduction: - Males and females begin
the reproductive cycle by migrating from
their feeding grounds to breeding grounds
which may be separated by several thousand
kilometres. Courtship and mating occur
primarily in the offshore waters of the
breeding ground.
Nesting
Several weeks after mating, the females come
ashore to nest, mostly at night and dig out a
flask shaped nest with their hind flippers.
This may be two to three feet deep depending
on the size of the turtle. They lay about 100 –
150 eggs in the nest and fill it with sand and
return to the sea.
Hatching
Sea turtle eggs are incubated by metabolic
heat and the heat of the sun. The incubation
time for most species is between 45 and 70
days. The eggs then hatch simultaneously
over a period of a few days and hatchlings
then emerge from the nest together (to
swamp predators) usually at night and then
they orient themselves to wave direction and
start to swim against it.

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Development of hatchlings
Young turtles spend their lives in a variety of foraging
habitats. The hatchlings are usually carried on
transoceanic gyres and currents. The juveniles and sub
adults of some species spend many years in near shore
developmental habitats after the pelagic stage.
Adult migrations
Development to maturity may take 10 to 15 years in
most turtles and maybe 30 years. Once they have
reached sexual maturity, both males and females leave
their feeding grounds and migrate to the near shore
waters of the nesting beach. Once mating is completed,
males will return to their adult feeding grounds. Females
return to their feeding grounds once they have nested.
Life cycle of sea turtle
Distribution of sea turtle in world
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 flat back
sea turtle is found solely on the northern coast of Australia. Kemp's ridley sea turtle is
found solely in the Gulf of Mexico and along the East Coast of the United States.
Status of sea turtle in India
Scientists recognise seven living species of sea turtles, which are grouped into six genera.
These species include: the olive ridley (Lepidochelys olivacea), loggerhead (Caretta
caretta), green (Chelonia mydas), hawksbill (Eretmochelys imbricata), Kemp’s ridley

5. (Lepidochelys kempii), Australian flatback (Natator depressa) and leatherback
(Dermochelys coriacea) turtle. Of the seven species, the Australian flat back is the only
one that isn’t either endangered or critically endangered. All are found in coast of the
maritime state of India.
Green sea turtle
Green turtles are the largest of all the hard-shelled
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sea turtles, but have a comparatively
smaller head. They are large in size, attaining
about 120 cm in length and weighing about 136-
159 kg.
Hawksbill
One of the smaller sea turtle species, the
hawksbill turtle gets its name from its narrow,
elongated head which tapers sharply with a V-shaped
lower jaw. The carapace is orange,
brown or yellow in colouration. Adult
hawksbills measure about 76-91 cm in length
and weigh around 40-60 kg
Leatherback
Largest among all the sea turtle species,
leatherbacks get their name from the unique shell
composition that make it appear “leathery”.
Leatherbacks are known to travel great distances,
and dive the deepest, when compared to other sea
turtles. They growing up to 170 cm in length and
weighing up to 500 kg.
Loggerhead
Adult loggerheads measure between 75 and 100 cm in
length and typically weigh up to 159 kg. Loggerheads
are named after their exceptionally large heads. The
carapace is reddish-brown with a yellowish-brown in
colour

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Olive ridley
The olive ridley is the smallest of all the sea turtle
species. It gets its name from the olive green
colouration of its carapace (shell). An adult typically
measures between 62 and 70 cm in length and
weighs about 35-45 kg. Juveniles are charcoal grey
in colour, while adults are a dark greyish green.
Australian flat back
The Australian flat back (Natator depressa) is
endemic to the continental shelf of Australia and is
so called because of its flattened carapace. The
adults weigh about 200 kg.
The Kemp's ridley
The Kemp’s ridley (Lepidochelys kempii) turtle
is also known as the Atlantic ridley turtle and is
found in the Atlantic Ocean and the Gulf of
Mexico. Adults weigh about 50 kg and are about
60 – 90 cm in length and closely resemble olive
ridleys.
Distribution of sea turtle in India
Gujarat
Nesting species: olive ridley, green .Non-nesting species: leatherback, hawksbill.
Maharashtra
Nesting species: olive ridley, green (unconfirmed). Non-nesting species: leatherback
(rare), hawksbill (rare)
Goa
Nesting species: olive ridley, leatherback (rare) .Non-nesting species: green
Karnataka
Nesting species: olive ridley. Non-nesting species: green, leatherback. The three coastal
districts of the state are Dakshina Kannada, Udipi and Uttara Kannada.

7. Kerala
Nesting species: olive ridley. Non-nesting species: green, hawksbill, leatherback.
Tamilnadu
Nesting species: olive ridley. Non-nesting species: green, leatherback, loggerhead,
hawksbill.
Andhra Pradesh
Nesting species: olive ridley. Non-nesting species: leatherback, hawksbill, loggerhead,
green.
Orissa
Nesting species: olive ridley. Non-nesting species: green, hawksbill, leatherback. There
are three recorded mass-nesting beaches in Orissa; Gahirmatha, Rushikulya and Devi
River mouth, although mass nesting has not occurred at Devi mouth in the last decade.
West Bengal
Nesting species: olive ridley. Non-nesting species: green (rare), loggerhead (rare).
Current records indicate that the olive ridley is the most common and abundant marine
turtle along this coast and is reported to visit Digha, Shankarpur, Junput sand bar,
Nayachar and the sea-facing islands of the Sundarbans.
Andaman and microbar islands
Nesting species: olive ridley, green, hawksbill, and leatherback. The hawksbill and
leatherback populations in the Andaman's and Microbars are the largest in India and are
most important for the northern Indian Ocean. The green turtle is the most common and
extensive species throughout both island groups.
Lakshadweep
Nesting species: hawksbill, green, olive ridley. Non-nesting species: leatherback (rare).
Ecological importance
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.
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.
Economic importance
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 Sea turtle harvests worldwide are for food.
 Many parts of the world have long considered sea turtles to be fine dining.

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 Sea turtles as a source of protein.
 Turtle eggs is used for consumption.
 Tortoiseshell, a traditional decorative ornamental material used in japan and china.
 The skin of the flippers is prized for use as shoes and assorted leather goods.
Valuation
 Significant contribution to GDP
 Taxes paid to government
 Jobs and wages dependent on sea turtles.
 Jewellery, instruments, sunglasses or wall decorations.
 Recreation purpose.
Threats to sea turtles
Artificial lighting: When a sea turtle hatches, its evolutionary instincts push it to move
towards the brightest light in view, which naturally would be the sun or the moon, leading
them toward the ocean horizon and into their new ecosystem. With the invention of the
light bulb the hatchlings become easily confused and turned around, few of them making
successful treks to the ocean. Studies support artificial light as the leading cause for
hatchling disorientation, showing that in 1999, 51% of the nests studied showed signs of
confusion with one-fourth of all the hatchlings headed in the wrong direction.
Ocean plastic
Discarded plastic bags floating in the ocean resemble jellyfish, a common food of sea
turtles. If a turtle eats a plastic foil, it tends to clog the turtle's digestive system and results
in the animal dying. There have been many cases of dissection showing plastic foil and
other debris inside turtle’s stomachs and intestines.
Oil spills
Oil spills are particularly dangerous to sea turtles. Sea turtles are still at risk when they
surface for air, where oil can get in their eyes, skin, and lungs which can lead to significant
health problems. Oil is also a cause for the death of sea grass. Eggs is still at risk due to
either oil in the sand or contamination. If the eggs in the nest have contact with oil while
in the last half of their incubation phase, the rate of hatchling survival sharply decreases
and those that do survive have a greater chance of physical deformities.
Marine pollution
Most dangerous ocean pollutants include toxic metals, fertilizers, untreated waste,
chemicals and a variety of petroleum products. Breeding season is in particular a
dangerous time for sea turtles due to the pollution of beach nesting sites. Contamination
of their diet can lead to disruption of digestion as well as physical injury of the sea turtles’
digestive tracts. A study in 1994 at Atlantic coast, 63% of hatchlings surveyed had been

9. found to have ingested tar leading to oesophageal swelling that can dislocate the
intestines and liver leading to serious buoyancy issues as well as excessive swelling.
Magnetic interference
Ferrous metal wire mesh screens are commonly used to protect sea turtle nests from
predators' excavating and devouring the eggs and hatchlings. A new concern is that
nestlings' delicate magnetic sense may not develop normally in the presence of the
magnetic field interference from these steel mesh cages. Gravid turtles or their hatchlings
may also be affected by the presence of magnetic fields arising from power cables, iron
debris, steel seawalls or other human activities that locally modify earth's magnetic field.
Fishing
Long line, trawl, and gillnet fishing are three types of fishing with the most sea turtle
accidents. Deaths occur often because of drowning, where the sea turtle was ensnared
and could not come up for air. Another dangerous aspect of fishing that is common is
when sea turtles inadvertently swallow sharp hooks, which can get stuck within the soft
tissue of the throat and stomach, or damage vital organs and intestines. According to an
article in AAAS & Science, over 8 million sea turtles have died over the past twenty years
due to injuries caused by being accidentally caught by fishing boats.
Global warming
This rise in sea levels has been a factor in the loss of beach, which for sea turtles means
less nesting area. As the overall temperature of the earth rises, so does the temperature
of the sand, which diminishes the rate of hatchling survival. The temperature of the sand
also affects gender, as higher temperatures have been shown to yield more female
hatchlings. Changes in climate also influence currents and change the number and
location of prey species. Water that is too warm can also cause coral bleaching, which is
detrimental to reefs that are essential to certain species, such as the Hawksbill sea turtle.
Disease
A disease known as fibropapillomatosis manifests
itself in turtles through external tumours. These
tumours often grow to be so large that they
hinder a sea turtle’s ability to see, eat, and swim,
therefore rendering the sea turtle unable to
survive. the causes of this disease are not clear,
many believe the source to be viral. These tumours
are either smooth or contain pointed projections
and they are red, pink, grey, black, or purple in
colour.
Law & policy (international).
International union for the conservation of nature and natural resources as the first
international forum (1963) for sea turtle research and conservation. In 1973, the
endangered species act was passed, providing protection for all sea turtle species. NOAA
9

10. national marine fisheries service (NMFS) and the U.S. Fish and wildlife service (USFWS)
administer the endangered species act with respect to marine turtles. NOAA fisheries has
the lead for the conservation and recovery of sea turtles when turtles are at sea. The
USFWS has the lead when sea turtles are on nesting beaches.
Law & policy (India)
The Indian Wildlife Protection Act (1972) lists all species of marine turtles in Schedule I,
thereby offering them the highest degree of protection. Under international law, India is
a signatory to CITES (Convention on International Trade in Endangered Species) and the
Convention on the Conservation of Migratory Species of Wild Animals (CMS). CITES
regulates international trade on sea turtles and their products but does not protect
habitat or control other threats to sea turtles. And according to the CMS, all seven species
of sea turtles require international cooperation for their conservation. But here again,
conservationists feel that not enough provision has been made for effective protection
and conservation.
Turtle excluder device
Sea turtles can be caught when bottom
trawling is used by the commercial shrimp
fishing industry. This results in large amounts
of other marine organisms being also caught as
by catch. 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. Turtle Excluder Devices (TEDs) have
reduced sea turtle by catch in shrimp nets by
97percent.
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Last note
 Beach management and hatchery programmes.
 Education and Awareness.
 Rehabilitation.
 By catch reduction.
 Reducing Overharvesting and Illegal Trade.
 Protecting Marine Turtle Habitat.
 Minimizing Climate Change Impacts.
 Satellite Tracking.

11. Turtle or tortoise
There is some confusion about the usage of terms 'turtle' and 'tortoise'. Basically, the
usage of these terms differs in accordance to the language in question. In British English,
the term 'turtles' is used for those species which are found in the sea, and 'tortoises' for
those inhabiting the land. In American English, the term 'turtles' is used as a general term
to all the species belonging to this family; and the sea-dwelling species are specifically
referred to as 'sea turtles'.
Reference
• "Marine Turtles." Office of Protected Resources. NOAA Fisheries, 11 Nov 2010.
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Web. 8 Dec 2010.
• Hirayama, R., & Tong, H. (2003). "Osteopygis (Testiness: Cheloniidae) from the
Lower Tertiary of the Ouled Abdoun phosphate basin, Morocco.
• Roy D Silva Last Updated: January 19, 2012.
• NOAA Education Resources: Sea Turtles Collection.
• http://seaturtlesofindia.org/?page_id=462.
• Turtle excluder device From Wikipedia, the free encyclopaedia.
• http://seaturtlesofindia.org/?page_id=180.
"For in the end we will conserve only
What we love. We will love only what
We understand. We will understand
Only what we are taught." - Baba Dion
Thank you

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