Classroom lesson · Wildlife · 🇬🇶 Equatorial Guinea

Leatherback Turtle

The world's largest turtle nests on Bioko's beaches

A large leatherback sea turtle on a dark sandy beach at night

Photo · Wikimedia Commons

What is it?

The leatherback is the largest turtle in the world, and some of the most important beaches for this magnificent creature are on the southern coast of Bioko Island. Unlike other sea turtles, leatherbacks have a soft, rubbery shell rather than a hard one. Every year, females return to the same beaches where they were born to lay their own eggs.

Tell me more

A fully grown leatherback turtle can measure over two metres from head to tail and weigh as much as 900 kilograms — heavier than a small car. Despite this size, they are graceful swimmers and can dive deeper than 1,000 metres. They feed almost entirely on jellyfish, and can eat over 100 kilograms of jellyfish in a single day.

Female leatherbacks come ashore at night to lay their eggs, usually returning to the exact beach where they were born many years earlier. Scientists believe they use the Earth's magnetic field — a bit like a built-in compass — to navigate thousands of kilometres across the ocean and find the right beach. The journey from feeding grounds in the Atlantic back to Bioko can be over 7,000 kilometres.

On Bioko's beaches, a female leatherback digs a deep hole in the sand with her back flippers, lays around 80 to 100 eggs the size of billiard balls, covers them carefully, then returns to the sea. The eggs hatch after about two months, and tiny hatchlings no bigger than a matchbox scramble toward the ocean. The beach is one of the most magical places in Equatorial Guinea on a hatching night.

Leatherbacks have lived on Earth for over 90 million years — they swam in the same oceans as the dinosaurs. Protecting nesting beaches like those on Bioko is vital because these turtles need undisturbed sand and dark skies to find their way. Local communities and conservation teams on Bioko work together each season to keep the beaches safe.

In the classroom

Walk your class through this in 15 minutes.

Talk together

Discussion prompts

  1. 01How do you think leatherback turtles navigate thousands of kilometres across the ocean using Earth's magnetic field?
  2. 02Female turtles return to the beach where they were born. Why might this instinct be helpful?
  3. 03What might happen to the turtle population if the nesting beaches on Bioko were disturbed?
  4. 04Leatherbacks have survived for 90 million years. What does that tell us about how well they are adapted to their environment?
Try this

Classroom activity

Map the leatherback's journey. On a simple map of the Atlantic Ocean, draw Bioko Island and label it as the nesting beach. Then draw a possible route of over 7,000 kilometres that a turtle might swim to its feeding grounds and back. Add three interesting facts along the route.