With the fascination surrounding marine life, we've curated an exciting and captivating series of the most intriguing facts about these magnificent creatures. Every week, we'll delve into the captivating world of one of our favourite sea dwellers, revealing their secrets and unique characteristics.
Sea turtles are fascinating creatures that have been around for more than 100 million years, coexisting with dinosaurs. Today, scientists recognize seven species of marine turtles: Hawksbill, Loggerhead, Leatherback, Olive ridley, Green, Flatback, and Kemp's ridley. Unfortunately, six of these species are in danger of extinction, and the flatbacks are listed as vulnerable.
Diverse Sizes and Record-Breaking Discoveries
Marine turtle species vary in size, with the Kemp's ridley measuring around 70 cm long and weighing up to 40 kg, while the leatherback can reach lengths of up to 180 cm and weigh a staggering 500 kg, over ten times heavier! Wales holds the world record for the largest marine turtle ever found. In 1988, a leatherback washed ashore, measuring 2.5 metres long, with a wingspan of 2.5 metres, and weighing over 900 kg. It was estimated to be around 100 years old at the time of its death.
Nurturing Life: Nesting and Hatchlings
Sea turtles show astonishing nesting behaviour. They dig nests in the sand using their rear flippers and lay a group of eggs called a clutch. Typically, they lay 100-125 eggs per nest and engage in multiple nesting events, occurring approximately two weeks apart over several months. About two months later, the hatchlings emerge from the sand, leaving the nest behind. Once out, these tiny turtles quickly start their risky journey to the ocean. While many threats jeopardise their survival, those that reach adulthood have overcome decades of challenges.
Temperature Determines Gender
Sand temperature affects the sex of sea turtle hatchlings. Cooler incubation temperatures produce male hatchlings, while warmer temperatures produce female hatchlings. Moderate temperatures result in a mix of both genders. This unique biological phenomenon emphasises the sensitivity of sea turtles to their environment and the importance of temperature in their survival.
Sea turtles have remarkable navigation skills, relying on Earth's magnetic field. Studies conducted in laboratories have confirmed that sea turtles can detect and use Earth's magnetic field for navigation. When it's time for a female sea turtle to lay her eggs, she returns to the beach where she once hatched. Some species undertake extensive journeys over 10 to 20 years before nesting, travelling vast distances.
Both male and female sea turtles undertake long-distance migrations in their lifetimes. Leatherback turtles can travel over 16,000 kilometres across the Pacific Ocean each year. Loggerheads have been observed migrating from Japan to Baja, covering a distance of approximately 13,000 kilometres. While some species exhibit extensive migrations, others like green turtles or olive ridleys prefer to stay within their local habitats.
Guardians of the Ecosystem
Sea turtles play a crucial role in maintaining the balance of the world's oceans. By grazing on seagrass beds and feeding on sea sponges, they prevent overgrowth, improve current flows, and enhance nitrogen production, promoting the healthy cultivation of flora and fauna. Sea turtles eat jellyfish and crustaceans, regulating their population numbers. Additionally, their shells provide a habitat for algae, barnacles, and small organisms, supporting a robust food web and nutrient recycling within marine ecosystems.
Anatomy and Adaptations
Sea turtles have both internal and external skeletons. The external skeleton, including the shell, protects and supports their internal organs. Comprising over 50 bones fused to the spine (except in leatherback turtles), it ensures their survival in harsh marine environments. Sea turtles cannot retract their heads and legs into their shells. Instead, their streamlined bodies with flipper-shaped legs help them with propulsion through the water. With beak-like mouths, they grasp and tear food, primarily jellyfish and other prey found in the ocean.
Desperate Journeys and Survival Struggles
The journey from the nest to the ocean is dangerous for sea turtle hatchlings. Many are preyed upon by birds and other predators before they even reach the water. Even those that make it to the ocean face many challenges, such as storms, pollution, plastics, and predators. Shockingly, less than 0.1% of all hatchlings survive their first two decades of life, with only one in a thousand reaching adulthood.
Survival Skills: Breathing and Diving
Sea turtles cannot breathe underwater and rely on visits to the surface for air. During hunting, they resurface more frequently, but while resting, they can hold their breath for an astonishing 4-7 hours. Their heart rate slows, beating only once every nine minutes to conserve oxygen. These adaptations allow them to dive deep into the ocean when searching for food, with some species reaching depths around 300 metres. The leatherbacks, with their collapsible lungs and unique physiological features, can venture even deeper, surpassing 900 metres.
Sea turtles are extraordinary creatures that have captivated humans for centuries. Their ancient origins, diverse species, nesting habits, migratory journeys, ecological contributions, and unique anatomy make them a subject of wonder and concern. Protecting these magnificent creatures and their fragile habitats is crucial for preserving the balance and biodiversity of our oceans for generations to come.
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