Vertebrates are animals that have spinal columns. They include jawless fish (such as lampreys), cartilaginous fish (such as sharks), bony fish, reptiles, amphibians, mammals and birds.

Vertebrates make up only about 5% of animal species. The other 95% are invertebrates - animals that do not have spinal columns.

The first vertebrates lived about 530 million years ago, during the Cambrian explosion, when many different types of organisms appeared on Earth for the first time. These earliest vertebrates were jawless fish.

Bottlenose dolphinThe spinal column is a stiff rod that runs along the length of a vertebrate's body.

It is sometimes called a backbone.

Spinal columns allow large vertebrates to support their own weight.

Vertebrates can grow to be very large.

The largest animals on land and in the oceans are vertebrates.

The spinal column is divided into segments known as vertebrae. This gives it flexibility.

A bundle of nerve tissue, known as the spinal cord, is contained within the spinal column.

The brain, which is the control center of the nervous system, bulges out from the front of the spinal cord.