It is slippery, soft and slimy, burrows in the moist soil and many just find it disgusting – the earthworm. Most of us know it when it comes to the surface in heavy rain and ends in puddles or, possibly, as fish bait; but earthworms are true natural wonders and extremely useful. Only a very small percentage of all animals are vertebrates. These animals, such as mammals, birds, reptiles, amphibians and fish, all have a vertebral column. Over 90% of our fauna are invertebrate animals.