Blue whales can live for up to ninety years. They travel all over the world, usually in pairs or small groups. As they swim, they talk to each other by singing. Their songs can be heard 1,200 kilometres away! In the summer they live in the sea near the North and South Poles. In the winter they swim to warmer water. Their babies are born in the warmer water in the winter. When the babies are born, they are already 8 metres long! But although these large animals are so big, not many people see them. There is a lot of sea to hide in!