Ocean Facts for Kids
Deep-sea facts and ocean wonders
At the bottom of the Mariana Trench, the water pressure is more than 1,000 times greater than at the surface — enough to crush a human instantly. Special deep-sea vehicles use thick metal walls to withstand this force.
Coral reefs are sometimes called the rainforests of the sea because they are home to about 25% of all marine species, even though they cover less than 1% of the ocean floor. They are made up of tiny living animals called coral polyps.
Australia's Great Barrier Reef is the world's largest coral reef system, stretching over 2,300 kilometres. It is so enormous it can be seen from space.
An octopus has three hearts — two pump blood to its gills, and one pumps it to the rest of its body. Its blood is blue because it contains copper instead of iron.
Sharks have been swimming in the oceans for more than 450 million years, making them older than trees on land. They survived all five of Earth's major mass extinction events.
More than 80% of the ocean has never been explored or mapped in detail. Scientists believe there could be millions of undiscovered species living in its dark depths.
Dolphins sleep with one eye open and keep half their brain awake so they can continue breathing and watch for danger. This is called unihemispheric sleep.
Sea turtles can sense Earth's magnetic field and use it like a compass to navigate across thousands of kilometres of open ocean. They often return to the very beach where they were born to lay their own eggs.
Jellyfish have no brain, no heart, and no blood, yet they have survived in the oceans for more than 500 million years. Their bodies are made up of about 95% water.
Clownfish can change their sex during their lifetime — all are born male, and the dominant fish in a group can become female if needed. They live among the stinging tentacles of sea anemones, which do not harm them.