Green Sea Turtle _Chelonia mydas_

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Green Sea Turtle _Chelonia mydas_ Powered By Docstoc
					                                               Sandy Beach Reptiles
140 million years ago, reptiles were the largest animals in the oceans. Their place has since been taken by mammals,
leaving few reptiles that are wholly marine. Of these, turtles are the most widespread, and sea snakes are the most diverse.
Almost all are confined to warm-water regions, with the largest numbers around coasts and on coral reefs. We will focus
on Sea Turtles for the sandy beach ecosystems.

        A. Anatomy-
        Marine reptiles have several adaptations for life in the sea. Turtles have a low, streamlined shell, or carapace, and
        broad, flattened forelimbs that beat up and down like wings. All reptiles breathe air, and marine species have
        valves or flaps that prevent water entering their nostrils when they dive. Marine reptiles all need to expel excess
        salt. Marine turtles lose salt in their tears. Crocodiles do this through salt glands in their mouths. The marine
        iguana has salt glands located on its nose.

        B. Habitat
        Most marine reptiles live close to the shore, or return to it to breed. Apart from the leatherback turtle, most marine
        reptiles depend on external warmth to remain active, which restricts them to tropical and subtropical waters.
        Thanks to their low metabolic rate, marine reptiles can remain underwater for long periods.
        C. Food and Feeding
        Most marine reptiles are carnivorous. Green turtles feed on seagrass when they become adult, while other marine
        turtles are carnivorous throughout their lives. The marine iguana is the only marine reptile herbivore for its entire
        life.
        D. Reproduction
        All marine reptiles, except for sea snakes, lay their eggs on land. Many of them breed on remote beaches and
        Islands, and the adults sometimes arrive simultaneously and in large numbers. The nest temperature during
        incubation determines the sex ratio of the hatchlings. Once the eggs have hatched, growth is fast, but mortality
        can be high. Parental care is rate in marine reptiles, with the exception of female crocodiles that guard their nests
        and carry their young to water after they have hatched.
                                             Sea Turtle Species:
                                      Green Sea Turtle (Chelonia mydas)
TEXAS STATUS
       Threatened
U.S. STATUS
       Threatened, Listed 7/28/1970
PROTECTION STATUS NOTES
       The Green sea turtle is currently designated as Endangered in
       the breeding colony populations in Florida and on the Pacific
       coast of Mexico. It is designated Threatened throughout the
       remainder of its range.
DESCRIPTION
       Green sea turtles have a yellowish green body with dark spots
       on their head and flippers. Their shell is dark brown or olive
       colored and up to 55 inches long. Green sea turtles can grow to
       weigh 850 pounds. They are the most common turtle in subtropical and tropical waters, where it is often seen in
       eelgrass beds and on coral reefs.
LIFE HISTORY
        Green sea turtles range throughout the Atlantic, Pacific, and Indian Oceans primarily in the tropical regions.
        During the day, green sea turtles feed in the seagrass beds that grow in shallow waters. At night, they sleep on the
        shallow bottom and sometimes out of the water on rocky ledges. Although sea turtles are subject to predation
        throughout their life cycle, predation is particularly high during the first two years of life. The eggs are eaten by
        raccoons, skunks, opossums, mongooses, coatis, and dogs. Hatchlings are preyed upon by mammals, sea birds,
        crabs, and carnivorous fishes. Predation continues to be high until the turtles are big enough to avoid being
        swallowed. Sharks are a formidable predator throughout the life cycle of the green sea turtle.
        Their diet consists of mostly seagrasses and algae, with small amounts of animal foods such as sponges,
        crustaceans, sea urchins, and mollusks. The turtles migrate from nesting areas to feeding grounds, which are
        sometimes several thousand miles away. Most turtles migrate along the coasts, but some populations are known to
        migrate across the ocean from nesting area to feeding grounds. As a species that migrates long distances, these
        turtles face special problems associated with differing attitudes toward conservation in different countries.
        Green sea turtles can live from 30 - 50 years. Adults reach sexual maturity between 8 and 13 years of age. Adults
        mate every 2 to 3 years during the nesting season just off the nesting beaches. Nesting occurs in numerous places
        in the tropics, including the beaches of the Gulf of Mexico, the Caribbean and Florida, Bermuda and the Cayman
        Islands. The turtles nest from March to October, with greatest activity along Gulf of Mexico beaches between
        June and August.
        The females may nest several times during a season, laying as many as 145 soft, round white eggs per nest. The
        eggs incubate in the sand for 48 to 70 days. The incubation period is longer when the weather is cool. Hatchlings
        emerge from the nest mostly at night, race quickly to the surf and swim hurriedly toward the open ocean. The
        color of the hatchlings, black above and white below, is probably an adaptation to life near the surface in the open
        ocean, making them less conspicuous to fish and bird predators.
HABITAT
       Green sea turtles feed in shallow water areas with abundant seagrasses or algae. The major nesting
       beaches are always found in places where the seawater temperature is greater than 77 degrees
       Fahrenheit.
DISTRIBUTION
       In Texas, green sea turtles are found in the Gulf of Mexico. They occasionally visit the Texas coast.
OTHER
        The meat and eggs of the green sea turtle have long been a source of food for people. Although international trade
        of wild green sea turtles is against the law, capturing turtles for local consumption still persists in many central
        Pacific Islands, Southeast Asia and Indonesia, Indian Ocean islands, east coasts of Africa and Arabian peninsula,
        in Central and South America, and in Mexico. Exploitation of the nesting grounds either by human interference or
        pollution poses the greatest threat to these turtles. In the past, green sea turtles were often killed in large shrimp
        trawl nets. Today, turtle excluder devices (TED's) pulled by shrimp boats help reduce mortality from net
        entanglement.
                              Hawksbill Sea Turtle (Eretmochelys imbricata)
TEXAS STATUS
       Endangered
U.S. STATUS
         Endangered,
         Listed
        6/02/1970
DESCRIPTION
        The hawksbill
        sea turtle is a
        small to medium
        sized turtle with
        shell lengths up to 36 inches. They are known for their beautiful brown shell, mottled with dark and light spots and streaks,
        which was once commonly used to make tortoiseshell jewelry. They are named after its conspicuous beaked snout.
LIFE HISTORY
        Hawksbill sea turtles are the most tropical of all sea turtles. Hawksbill turtles nest primarily at night, but there are reports of
        daytime nesting, usually on uninhabited beaches. Although sea turtles are subject to predation throughout their life cycle,
        predation is particularly high during the first two years of life. The eggs are eaten by ghost crabs, raccoons, skunks,
        opossums, mongooses, and dogs. Hatchlings are preyed upon by mammals, sea birds, crabs, and carnivorous fishes.
        Predation continues to be high until the turtles are big enough to avoid being swallowed. Sharks are a formidable predator
        throughout the life cycle of the hawksbill.
        This carnivorous turtle has a highly variable diet consisting mostly of invertebrates such as sponges, jellyfish, crustaceans,
        sea urchins, and mollusks. In captivity, adults reach sexual maturity between 3 and 5 years of age, although wild turtles may
        take much longer to reach maturity. They can live as long as 30 - 50 years. Adults mate off the nesting beaches every 2 to 3
        years during the nesting period, generally April through November. Female hawksbill turtles nest alone or sometimes in small
        groups. As with other sea turtles, females return to lay their eggs on or near the same beach where they hatched. Scientists
        believe that sea turtles navigate by using their own innate global positioning system. Hatchlings are born with the ability to
        navigate using the earth's magnetic field.
        The females may nest several times during a season, laying as many as 200 soft, round white eggs per nest. The eggs
        incubate in the sand for 47 to 75 days. The incubation period is longer when the weather is cool. Hatchlings emerge from the
        nest mostly at night, race quickly to the surf and swim hurriedly toward the open ocean. Nesting occurs in numerous places in
        the tropics. In the Americas, these include the beaches of the Yucatán Peninsula, southern Cuba, Costa Rica, islands of the
        Caribbean such as Virgin Islands, Jamaica, Dominican Republic, Turks and Caicos, and Grenada, northeastern Brazil, and
        Pacific coasts of Mexico and Panama.
HABITAT
        Hawksbill turtles live in clear offshore waters of mainland and island shelves. They are more common where coral reef
        formations are present. In fact, they rarely stray far from the shallows and coral reefs. They are less migratory than other
        marine turtles. Hawksbill turtles nest on sandy beaches, often in the proximity of coral reefs. On land, it has a distinctive gait
        (walking stride). They move their flippers in diagonally opposite pairs, whereas other marine turtles move their front flippers
        together…the same action they use when swimming.
DISTRIBUTION
        Hawksbill sea turtles are found primarily in warmer waters of the Atlantic, Pacific, and Indian Oceans from Japan to Australia
        and the British Isles to southern Brazil. They are also found in the southern waters of Florida, the Gulf of Mexico, and the
        Caribbean. In Texas, the hawksbill is found in the Gulf of Mexico and occasionally on the Texas coast.
OTHER
        The hawksbill's brightly colored, thick scutes covering the carapace (top of the shell) are the source of "tortoise-shell" which
        has been used for centuries to make jewelry. Handicrafts made of tortoise-shell appear in many ancient cultures, in places like
        China, Ceylon, India, Oceania, and Rome. With the CITES (Convention on International Trade in Endangered Species)
        restrictions, international trade in tortoise-shell has significantly decreased, but harvest of the turtle for its shell is still a threat
        to its survival in some areas of the world. Attempts at farming these turtles have been unsuccessful.

         The meat and eggs of the hawksbill have long been a source of food for people, although the meat is considered toxic in
         some areas due to the food items consumed. Human exploitation of the nesting grounds and pollution pose long term threats
         to its survival. In the past, hawksbill sea turtles were often killed in large shrimp trawl nets. Today, turtle excluder devices
         (TED's) pulled by shrimp boats help reduce mortality from net entanglement

                                  Leatherback Sea Turtle (Dermochelys coriacea)
TEXAS STATUS
Endangered
U.S. STATUS
Endangered, Listed
6/02/1970
DESCRIPTION
        The
        Leatherback is
        the largest of all
        sea turtles, with
        weights of 1,300 lbs. and a carapace length of up to 8 feet.
        This turtle is unique because of the smooth leathery skin
        covering its carapace. Their head cannot retract into its
        shell. It is also different from most other turtles in that it can
        keep its body warmer than its surroundings, thanks partly to the thick layer of insulating fat beneath its skin. This allows it to
        wander much more widely than other turtles, reaching as far north as Iceland and almost as far south as Cape Horn.
        The leatherback’s throat contains dozens of backward-pointing spines that prevent jellyfish from escaping before they are
        completely swallowed. These endangered turtles often die after eating discarded plastic bags, which they mistake for jellyfish.
LIFE HISTORY
        The leatherback is one of the largest living reptiles, surpassed in size only by some species of crocodiles. Adults can be
        distinguished from all other species of sea turtles by their large size, spindle-shaped bodies, and leathery, unscaled carapaces.
        Research on captive turtles indicates that leatherbacks grow faster than any other marine turtle. Leatherbacks feed mainly on
        pelagic (open ocean) soft-bodied invertebrates such as jellyfish and tunicates. Their diet may also include squid, fish, crustaceans,
        algae, and floating seaweed. Highest concentrations of these prey animals are often found in areas where deep water comes to the
        surface (upwelling areas) and where ocean currents converge.
                 These giant turtles live at least 30 years and up to 50 years or more. Adults are believed to reach sexual maturity between 3
        and 4 years of age, although the age at which wild turtles reach maturity may be greater. Unlike most sea turtles, which nest in the
        spring and summer, leatherbacks usually nest in fall and winter. They arrive at the nesting beaches in large groups, forming
        "arribazones", where groups of females move onto the beach to lay their eggs over a period of a few days. The eggs incubate in the
        sand for 50 to 78 days. The incubation period is longer when the weather is cool. Hatchlings emerge from the nest mostly at night,
        race quickly to the surf and swim hurriedly toward the open ocean. Predation is high during the first two years of life. The eggs are
        eaten by raccoons, skunks, opossums, mongooses, coatis, and dogs. Hatchlings are preyed upon by mammals, sea birds, crabs,
        and carnivorous fishes. Predation continues until the turtles are big enough to avoid being swallowed. Sharks are a formidable
        predator throughout the life-cycle of the leatherback.
HABITAT
        The leatherback prefers the open ocean and moves into coastal waters only during the reproductive season. Although small groups
        may move into coastal waters following concentrations of jellyfish, these turtles seldom travel in large groups. Leatherbacks inhabit
        primarily the upper reaches of the open ocean, but they also frequently descend into deep waters from 650 to 1650 feet in depth.
        They roam huge distances…one leatherback tagged off the coast of South America was later found on the other side of the Atlantic,
        4200 miles away!
DISTRIBUTION
        In Texas, the leatherback sea turtle occurs in the Gulf of Mexico. It is a rare visitor to the Texas Gulf Coast.
OTHER
        Disturbance of the nesting grounds is the most serious threat to the leatherback. Although the flesh of this sea turtle is not eaten, the
        population has been threatened by egg- harvesting in countries such as Malaysia, Surinam, the Guianas, the west coast of Mexico,
        Costa Rica, and in several Caribbean islands. leatherbacks were killed in the past for the abundant oil they yield, which was used for
        oil lamps and for caulking wooden boats. Ingesting plastic bags and other plastic wastes are another cause of death for
        leatherbacks. The turtles confuse plastic wastes with one of their favorite foods - jellyfish. When swallowed, plastics can clog a
        turtle's throat, esophagus, and intestines.

        The leatherback sea turtle is considered an endangered species throughout its worldwide range. It is listed in Appendix 1 of the
        CITES (Convention on International Trade in Endangered Species), a list of the most highly endangered animals worldwide. In the
        majority of countries, this turtle is fully protected by law, however, enforcement of this protection is difficult in many areas.
        Indiscriminate poaching of eggs and capture of adults at sea or in nesting areas is still widespread. Although captive breeding has
        been attempted, it has been largely unsuccessful.
  Loggerhead Sea Turtle
     (Caretta caretta)
TEXAS STATUS
       Threatened
U.S. STATUS
       Threatened, Listed
       7/28/1978
DESCRIPTION
       After the leatherback, the
       loggerhead is the second-
       largest marine turtle. Loggerhead sea turtles have characteristically large, blunt
       heads with powerful jaws and a steeply domed carapace. Adults weigh 170 to
       500 lbs. and have a shell up to 45 inches in length.
LIFE HISTORY
         Although sea turtles are subject to predation throughout their life cycle, predation is particularly high during the first two years
         of life. Highest predation occurs during incubation and during the hatchlings' race to the sea. The eggs are eaten by ghost
         crabs, raccoons, skunks, foxes, and dogs. Hatchlings are preyed upon by mammals, sea birds, crabs, and carnivorous fishes.
         Predation continues to be high until the turtles are big enough to avoid being swallowed by large carnivorous fishes such as
         groupers, snappers, and jacks. Sharks are a formidable predator throughout the life cycle of sea turtles, although larger turtles
         can often avoid a shark attack by presenting the flat side of the plastron or carapace to prevent biting. Loggerhead sea turtles
         can live at least 30 years and up to 50 years or more.

         Although feeding behavior may change with age, this species is carnivorous throughout its life. Hatchlings eat small animals
         living in seagrass mats which are often distributed along drift lines and eddies. Juveniles and adults show a wide variety of
         prey, mostly such as conchs, clams, crabs, horseshoe crabs, shrimps, sea urchins, sponges, fishes, squids, and octopuses.
         During migration through the open sea, loggerheads eat jellyfishes, pteropods, floating molluscs, floating egg clusters, squids,
         and flying fishes.

         This is the only sea turtle that can nest successfully outside of the tropics, but the summer surface water temperature must be
         over 68 degrees Fahrenheit. As with other sea turtles, females return to lay their eggs on or near the same beach where they
         hatched. Unlike other sea turtles, courtship and mating usually do not take place near the nesting beach, but rather along the
         migration routes between feeding and breeding grounds. Females may nest several times during a breeding season (April -
         September), laying as many as 190 soft, round white eggs per nest. The eggs incubate in the sand for 55 to 62 days. The
         incubation period is longer when the weather is cool, and there is evidence that cooler incubation temperatures produce more
         male hatchlings. Hatchlings emerge from the nest mostly at night. After the majority of the hatchlings appear at the surface of
         the nest, they start a frenzied race toward the surf and out to sea.

         Loggerhead hatchlings and juveniles are frequently associated with sea fronts (areas where ocean currents converge),
         downwellings, and eddies, where floating open ocean animals gather. The time that young turtles remain in these places
         feeding and growing is called the "lost year". During this period, young turtles float on rafts of seaweed with the currents,
         feeding on organisms associated with sargassum mats.
HABITAT
         Loggerheads are capable of living in a variety of environments, such as in brackish waters of coastal lagoons, river mouths,
         and tropical and temperate waters above 50 degrees Fahrenheit.
DISTRIBUTION
         They are found worldwide. The major nesting beaches are located in the southeastern United States, primarily along the
         Atlantic coast of Florida, North Carolina, South Carolina, and Georgia. In Texas, they are found in the Gulf of Mexico and are
         occasional visitors to the Texas coast. Only minor and solitary nesting has been recorded along the coasts of the Gulf of
         Mexico.
OTHER
         Until the 1970's, loggerhead turtles were commercially harvested for their meat, eggs, leather, and fat. Its meat and leather
         are not as valuable as the green sea turtle, and its shell is of less value than the hawksbill. However, in places where
         regulations are not enforced, the harvest of turtle meat and eggs remains a problem. Because of their feeding behavior and
         their habit of wintering in shallow waters, loggerheads, along with Kemp's Ridley sea turtles, are more likely to be caught and
         drowned in large shrimp trawl nets. Today, turtle excluder devices (TEDs) pulled by shrimp boats help reduce mortality from
         net entanglement by allowing turtles to escape from the nets.
                               Kemp's Ridley Sea Turtle (Lepidochelys kempii)
TEXAS STATUS
       Endangered
U.S. STATUS
       Endangered,
       Listed
       12/02/1970
DESCRIPTION
        Kemp's Ridley sea
        turtles are the
        smallest marine
        turtle, growing to 27-32 inches (68 to 82 cm) long and weigh on average 75-100 pounds (33 to 45 kg). They are also the most
        threatened. Distinguishing characteristics include a dark gray to gray-green carapace (upper shell), cream to tan plasteron
        (lower shell), streamlined shells, and appendages shaped like flippers. The turtle's dark, spotted head and flippers contrast
        sharply with its pale body.
LIFE HISTORY
        The male Kemp's Ridley spends its entire life in the water while the female only comes ashore to nest, sometimes joining
        large groups of nesting females called arribazones. The Kemp Ridley is different from other turtles in that the females crawl
        out of the sea at the same time as other females, and they lay their eggs in mass nestings. A female will only lay eggs during
        the day. She will come back to the same beach to nest year after year. About 125,000 hatchlings leave nests on North
        American shores, but only one percent of those will survive to sexual maturity. Sexual maturity is reached at about 10-15
        years for females. Little is known about the males. Each one will lay as many as 100 soft, white eggs during nesting season.
        Each turtle digs a hole in the sand, deposits her eggs, and returns to the sea. In 50-55 days, the eggs hatch and the baby
        turtles (hatchlings) rush to the water and out to sea. As hatchlings, Ridleys weigh about 0.5 ounces (14 g) with a shell the size
        of a half-dollar.
                   Their diet consists mostly of crabs; also shrimp, snails, clams, jellyfish, sea stars, and fish. Predators of the Kemp's
        Ridley sea turtle include humans (hunting, boat propellers, nets, and refuse), followed by natural predation by shore birds,
        sharks and other sea animals. Individuals surviving to adulthood may live 30 years and possibly up to 50 years. After at least
        10 years at sea, adult females return to nest at the same beach where they hatched. Some scientists believe that baby sea
        turtles may remember, or "imprint" on, the particular smell, chemical make-up, or magnetic location of the beach where they
        hatched. Others point out that sea turtles have magnetite, an iron ore, in their brains that they may use to navigate along the
        Earth's magnetic fields.
                   If the water grows cold, these sea turtles can adjust their metabolic rate and can remain underwater for hours. Turtles
        can go two to three months without food. Sea turtle "tears" are their way of ridding their body of saltwater through special
        glands. Eggs placed in a warm incubator tend to hatch as female turtles. Eggs kept at cooler temperatures hatch as males.
        The Kemp's Ridley is the smallest of all the sea turtles. It is also known as the tortuga lora in Mexico, which means "parrot
        turtle" in reference to the beak-like shape of its head.
HABITAT
        They prefer open ocean and gulf waters with the females only coming ashore to lay eggs in beach sand. Young Kemp's Ridley
        sea turtles float on large mats of sargassum (a type of brown algae) in the Gulf of Mexico and Atlantic Ocean.
DISTRIBUTION
        Kemp's ridley sea turtles are found in the coastal waters and bays of the Gulf of Mexico and Atlantic Ocean.
OTHER
        For more than 150 million years, sea turtles have roamed the earth. Although many sea turtle species are in danger, the
        Kemp's Ridley sea turtle is the most endangered species worldwide. The Kemp's Ridley sea turtle was placed on the
        Endangered Species List in 1970. Over the centuries, people have harvested the eggs and killed the turtles for their meat and
        leather-like skin. Between the 1940s and 1960s, the population crashed as people harvested truckloads of eggs and sold
        them in small towns in Texas and Mexico. More recent threats include suffocation in shrimpers' large nets and ingesting
        floating trash that they mistake for food. Governments of the Mexican states of Tamaulipas, Colima and Jalisco were the very
        first to become involved in the protection of sea turtle eggs. The nesting beach at Rancho Nuevo, Tamaulipas, Mexico is the
        primary nesting site for these turtles. It is the only known major nesting beach for this species in the world. Thanks to the work
        of a large team of scientists, a secondary nesting population has been established on Padre Island National Seashore. To
        continue the success of this secondary site, citizens are asked to leave the animals alone, but report any sightings to a park
        ranger or local game warden.

				
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