Sea Turtles

Sea turtles are air-breathing reptiles with streamlined shells and powerful flippers adapted for ocean swimming. Unlike land tortoises, sea turtles cannot retract their heads into their shells. Their front flippers function like wings, providing lift and propulsion through the water. Sea turtles have specialised salt glands near their eyes that excrete excess salt — the 'tears' often seen on nesting females are not emotional but functional. They are ectothermic (cold-blooded) but the leatherback turtle has some capacity for thermoregulation, allowing it to survive in cold northern waters.

Sea turtles possess one of the most remarkable navigation systems in the animal kingdom. They detect the Earth's magnetic field using magnetite crystals in their brains, effectively reading a magnetic map of the ocean. This allows them to navigate thousands of kilometres of open ocean with extraordinary precision, returning to the exact beach where they hatched — sometimes decades later. Loggerhead turtles nesting in Florida have been tracked crossing the Atlantic to feeding grounds off the coast of Africa and back. The mechanisms by which hatchlings imprint on their birth beach's magnetic signature remain an active area of research.

Female sea turtles return to their natal beaches to nest, typically every two to five years. Nesting occurs at night, when females haul themselves up the beach, excavate a nest chamber with their rear flippers, and deposit 80–120 eggs before covering the nest and returning to the sea. The temperature of the sand determines the sex of the hatchlings — warmer temperatures produce more females. After 45–70 days, hatchlings emerge and make their way to the sea, guided by the natural light horizon over the ocean. This journey is one of nature's most perilous — predators take a heavy toll, and artificial lighting from coastal development disorients hatchlings.

All seven sea turtle species are threatened with extinction. Threats include egg collection, hunting for meat and shells, bycatch in fishing gear, plastic ingestion, coastal development destroying nesting beaches, boat strikes and climate change. Rising sand temperatures due to climate change are skewing sex ratios towards females, threatening future reproductive success. Conservation efforts include beach protection programmes, bycatch reduction devices in fishing gear, satellite tracking to identify critical habitats, and community engagement with coastal communities. International cooperation is essential as sea turtles cross multiple national jurisdictions during their migrations.