The famous naturalist looks at why underground animals evolved in a very different way from those on the surface. From 2009.
Underground animals are very different to the animals that spend their life on the surface. They are a different shape, their senses are tuned in a very different way and they manifestly come from a different world.
Does this explain the stare of the snake?
Series of talks by Sir David Attenborough on the natural histories of creatures and plants from around the world.
First broadcast on BBC Radio 4 in August 2009.