They were already present on our planet long before the appearance of the dinosaurs. There are 480 different species in all the world’s oceans except Antarctica. They live for a very long time: some adult specimens reach the age of 400 years. This is much more than the bowhead whale (210 years old) or the giant tortoise (255 years old).
They are not the oldest living things on Earth: jellyfish have been there for at least 500 million years. Sponges, generally considered the oldest animals in the world, since 760 million years.
Due to overfishing, some shark populations have dropped by more than 95% in just 30 years.