Oceans and seas cover 70% of the whole of our planet. Under all that water there is an amazing hidden world where lots of amazing creatures live. Scientists believe there are about one million different species living in the oceans and seas. Some we know quite a lot about, some are quite mysterious and some sea creatures have incredibly never even been seen by humans as they are hiding from us in all that water, but they are out there somewhere!

There are so many creatures living on Earth, some are very similar to each other and some couldn’t be more different, so because of this we sort them into different groups.

All creatures are sorted into two main groups, vertebrates and invertebrates. Vertebrates are creatures that have a backbone. This means they have a skeleton, including a spine inside supporting their body (like we do.) While invertebrates don’t have a backbone, which means they don’t have a skeleton inside their body at all. This means they might be all squishy or they might have protection, such as a shell on the outside of their body.

Vertebrates and invertebrates are then split into further groups, depending on their similarities and differences to other creatures. Vertebrates living in the sea include fish and mammals. Invertebrates that can be found living in the sea include crustaceans and mollusks.

In this topic we are going to learn about these different types of creatures.

Scroll through the pictures to learn about the different creatures that live in the oceans and seas of the world, or you can use the links below….