This book is part of a book series called What On Earth? .

This book has been graded for interest at 7-9 years.

There are 32 pages in this book. This book was published 2005 by Children's Press(CT) .

Kathryn Senior is a former biomedical research scientist who studied at Cambridge University for a degree and doctorate in microbiology. After four years in research she joined the world of publishing as an editor of children's science books. She has now been a full-time science writer for 8 years.