Animal Groups

This site tells the story of the history of the universe. Click Earlier and Later to follow the story.
Note: Many facts have been simplified to make them easier to understand.
Our new free weekly podcast Time Crystal tells this story as sci-fi fantasy

It seems that the evolution of all successful animals began with ancestors similar to modern flatworms. Around 570 million years ago more advanced animals appeared.

Three types of animals were so successful that they are still the commonest animals today. All three types had hard outer coverings on their bodies. We call them

Molluscs
Arthropods
Vertebrates

All animals which do not have backbones (everything except the vertebrates) are called invertebrates.

The molluscs and arthropods belong to a group of animals called the protostomia, while the vertebrates are deuterostomia.