SECRETS OF THE SEAS

Take a deep dive beneath the waves as Melissa Hobson reveals the incredible animals that live in our seas.

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Our seas are full of secrets. Although the ocean covers more than 70% of Earth's surface, only around a quarter of the seafloor has been mapped.

Learning about marine ecosystems (living things and their environment) is important because what happens underwater also affects life on land. A healthy ocean provides oxygen, food and jobs for people all around the world. Plus, there are many wonderful marine animals living in these awe-inspiring habitats. Are you ready to meet some of the strangest and most spectacular marine creatures? Let's plunge into this amazing underwater world.

Meet the giants

Let's start with the largest animal in the world: the blue whale. Growing to around 30 metres in length - longer than a basketball court. With some of its blood vessels big enough for a small child to crawl through, the size of this marine mammal makes it easy for us to spot. Or does it?

Even the largest ocean animals can be hard for scientists to find. That's because they live far away from shore, travel huge distances, dive into deep waters, and can be nervous of boats. Scientists are still trying to learn how far blue whales travel and how long they live - the oldest recorded individual is thought to be around 110 years old.

Around half the size of a blue whale, at 17 metres long, humpback whales are still one of the biggest animals in the sea. They are known for their epic migrations, swimming thousands of miles each year between the chilly polar regions where they feed and the warm tropical waters where they breed.