Sandy Beach Reptiles

Sandy Beach Reptiles

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.

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.

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.

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

T

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

Distribution

In Texas, green sea turtles are found in the Gulf of Mexico. They occasionally visit the Texas coast.

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