Sea turtle: The traveller that crosses oceans by magnetic map

The sea turtle is the ocean's "traveller": it spends almost its whole life roaming the sea, and only the females come ashore to breed. It also has an astonishing ability — crossing entire oceans to return to the very beach where it hatched. Let's meet it.

Its body

The sea turtle is a reptile adapted to life in the sea. Its limbs have evolved into paddle-like flippers for swimming, and its body is flat and streamlined, ideal for moving through water. Unlike a land tortoise, a sea turtle cannot pull its head into its shell — its shell is flatter and harder, "redesigned" for swimming. It breathes with lungs, so it must surface regularly for air.

How it navigates

The sea turtle's most amazing skill is its sense of direction. Research shows it can sense the Earth's magnetic field, as if carrying a built-in "magnetic map". With that map, it can swim the open ocean for decades and still find the very beach where it hatched, climb ashore and nest. The journey often crosses an entire ocean — a remarkable feat.

Its breeding and its sex

A female digs a pit in the sand and lays her eggs there. Curiously, a hatchling's sex is not decided by genes but by the sand's temperature: warmer sand produces more females, cooler sand more males. So a warming climate affects the sex balance of the turtle family.

The threats it faces

Sea turtles live a long time — some reach decades or even a century. But today plastic waste (turtles often mistake bags for jellyfish) and entanglement in fishing nets put them in danger. Protecting the ocean is protecting sea turtles.

A note for grown-ups

You could talk with a child about how using one less plastic bag might save a sea turtle. Linking small everyday actions to animal protection turns environmental care from an abstract slogan into something a child can actually do.