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Unlock This CourseThe leatherback turtle (Dermochelys coriacea) is the largest marine turtle species and has one of the most fascinating life cycles in the ocean. These ancient mariners have been swimming our seas for over 100 million years, surviving since the time of the dinosaurs. Understanding their life cycle is crucial for marine conservation efforts, as leatherbacks face numerous threats throughout their long journey from tiny hatchling to massive adult.
Leatherbacks are truly remarkable creatures. Unlike other sea turtles, they don't have a hard shell but instead have a leathery carapace made of skin and flesh. They can grow up to 2 metres long and weigh as much as 900 kilograms - that's heavier than a grand piano!
Key Definitions:
Leatherbacks are the deepest diving turtles, reaching depths of over 1,200 metres. They're also the fastest swimming reptiles, reaching speeds of 35 km/h. Their body temperature can be up to 18°C warmer than the surrounding water!
The leatherback life cycle begins on tropical beaches around the world. Female leatherbacks return to the same beaches where they were born - a behaviour called natal homing. This incredible navigation ability allows them to find their way back across thousands of kilometres of ocean.
Mating occurs in the water near nesting beaches. Males never leave the ocean once they enter it as hatchlings, so all mating happens at sea. Females may mate with multiple males during the breeding season, which helps ensure genetic diversity in their offspring.
Female leatherbacks come ashore at night to nest, usually during high tide. The nesting process is exhausting and can take 1-3 hours. Here's what happens:
Females choose sandy beaches with the right temperature and minimal obstacles. They prefer beaches with coarse sand that drains well.
Using their rear flippers, females dig a flask-shaped hole about 75cm deep. This protects eggs from predators and temperature changes.
Females lay 80-120 eggs per nest. Not all eggs are fertile - some are smaller "yolkless" eggs that may help with nest structure.
Trinidad hosts one of the world's largest leatherback nesting populations. Grande Riviere beach sees over 500 nesting females each season. Local communities have transformed from egg collectors to turtle protectors, showing how conservation can benefit both wildlife and people. The beach now generates income through eco-tourism whilst protecting these ancient mariners.
Once eggs are laid and covered with sand, the incubation period begins. This stage typically lasts 55-75 days, depending on sand temperature. The incubation period is crucial because it determines not only whether the eggs will hatch successfully, but also the sex of the baby turtles.
One of the most fascinating aspects of turtle biology is that the temperature during incubation determines whether hatchlings will be male or female. This is called Temperature-Dependent Sex Determination (TSD).
Cooler temperatures (below 29.5°C): Produce mostly males
Warmer temperatures (above 29.5°C): Produce mostly females
Around 29.5°C: Produces a mix of both sexes
Developing turtle eggs face numerous challenges during their time buried in the sand:
After about two months of development, baby leatherbacks are ready to hatch. The hatching process is synchronised - most eggs in a nest hatch within a few days of each other. This group hatching behaviour, called emergence, helps improve survival chances.
Baby turtles use a special temporary tooth called a caruncle to break through their eggshell. Once hatched, they work together to dig their way up through the sand. This can take several days of coordinated effort.
Hatchlings usually emerge at night when it's cooler and there are fewer predators. They instinctively head towards the brightest horizon, which naturally would be the moon reflecting on the ocean.
Once on the surface, hatchlings must quickly reach the ocean. This "frenzy period" lasts 24-48 hours and gives them energy to swim continuously offshore.
Only about 1 in 1,000 hatchlings will survive to adulthood. Birds, crabs, fish and other predators take most hatchlings during their vulnerable early days.
Leatherback hatchlings are only about 6cm long and weigh just 45 grams when they hatch - small enough to fit in your palm! Despite their tiny size, they're born with an incredible ability to navigate using Earth's magnetic field. They can also dive to depths of 200 metres within their first few days of life.
Once hatchlings reach the ocean, they enter what scientists call "the lost years" - a period where young turtles are rarely seen and their behaviour is poorly understood. Recent research suggests that juvenile leatherbacks spend their early years in the open ocean, far from shore.
Young leatherbacks are believed to drift with ocean currents, feeding on small jellyfish and other soft-bodied creatures. Unlike adults who specialise in eating large jellyfish, juveniles have a more varied diet that may include small fish and crustaceans.
Leatherback turtles grow slowly compared to other reptiles. It takes 15-30 years for them to reach sexual maturity. During this time, they gradually increase in size and develop the specialised features that make them such effective jellyfish hunters.
Climate change is warming beach sand temperatures, which could lead to more female hatchlings being produced. This sex ratio imbalance could threaten future leatherback populations. Scientists are working with local communities to create shaded nesting areas and relocate nests to cooler locations.
Throughout their early life stages, leatherback turtles face numerous challenges that affect their survival rates. Understanding these factors is crucial for conservation efforts.
The leatherback turtle's life cycle is a remarkable journey of survival against incredible odds. From the moment a female digs her nest on a moonlit beach to the day a tiny hatchling takes its first swim in the vast ocean, each stage presents unique challenges and adaptations. Understanding this complex life cycle helps us appreciate why these ancient mariners need our protection and why every conservation effort matters in ensuring their survival for future generations.