This means they swim offshore, since close to the shore, wave crests run parallel to the beach. Loggerhead and green turtles can detect the orbital movement of waves and use this information to swim perpendicular to the waves crests. Hence, the use of moonlight by turtle hatchings as a navigational cue can be considered an ' evolutionary trap'. This navigational mechanism becomes a handicap if nesting sites are affected by artificial lighting since this can mean that hatchlings head towards the artificial lights rather than offshore towards the moonlit sea. Studies of loggerhead and leatherback hatchlings have shown that moonlight reflected from the sea is an important visual cue in guiding movement from the beach to the sea. The first part of the hatchling migration is called the 'frenzy period' which involves almost continuous swimming for the first 24–36 hours. Therefore, sea turtle hatchlings move offshore as an innate behaviour. Hatchling migration Įfficient movement of hatchlings away from the beach and shallow coastal waters is important in reducing the length of time that they are vulnerable to predators, which target the hatchlings on the beach or in shallow waters. There is evidence for this ability in juvenile green sea turtles. Some have suggested that juvenile and adult turtles might use the Earth's magnetic field to determine their position. The ability of adult sea turtles to travel to precise targets has led many to wonder about the navigational mechanisms used. Although the foraging movements of leatherbacks seem to be determined to a large part by passive drift with the currents, they are still able to return to specific sites to breed. Instead, they forage in the open sea in complex movements apparently not towards any goal. Others such as the leatherback sea turtle and olive ridley sea turtle do not show fidelity to any specific coastal foraging site. The loggerhead sea turtle uses a series of foraging sites. Some such as the green sea turtle shuttle between nesting sites and coastal foraging areas. Several main patterns of adult migration have been identified. The feeding and nesting sites of adult sea turtles are often distantly separated meaning some must migrate hundreds or even thousands of kilometres. They then maintain an offshore heading until they reach the open sea. Sea turtle hatchings emerge from underground nests and crawl across the beach towards the sea. Sea turtle migration is the long-distance movements of sea turtles (superfamily Chelonioidea) notably the long-distance movement of adults to their breeding beaches, but also the offshore migration of hatchings. Newly hatched sea turtles are also at risk of being hunted by animals such as birds, crabs, and raccoons as they move from their nests out to the sea.The green sea turtle migrates between its nesting sites and its coastal foraging areas. As they grow older, the turtles move to shallow waters along the coast, such as bays and lagoons, where they find sea grass to eat.Īdult green sea turtles face many threats, primarily from humans, including injuries from boat propellers, being caught in fishing nets, pollution, and poaching. The first few years of a green sea turtle’s life are spent floating at sea, where they feed on plankton. After about two months, the babies will use a special “egg tooth” to break their shells and hatch from their eggs. Then she’ll cover the eggs with sand and return to the sea. A female will dig out a nest with her flippers and lay a clutch of about 115 eggs. They have strong paddlelike flippers that help propel them through the water.įemale green sea turtles leave the water in order to lay eggs on the beach and will choose the same nesting spot as where they were born. Similar to other sea turtles, green sea turtles migrate long distances between their feeding grounds and their nesting sites, with recorded distances longer than 1,615 miles (2,600 kilometers). Jack dives into the Great Barrier Reef to wrangle Green Sea Turtles for wildlife conservation and study.
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