Michael Chinery
The invertebrates are the ‘creepy-crawlies’ of the garden. They are totally lacking in bone and what skeletons they have are on the outside of the body, in the form of a shell or a tough, horny coat. They far outnumber the backboned animals, the vertebrates, and there are literally millions of individuals in your garden, belonging to hundreds or even thousands of different species. It has been estimated that there are 20 million microscopic roundworms to a square metre of soil in some areas, and 90,000 individuals have been found in a single rotting apple.
This teeming assortment of mini-beasts plays a major role in the ecology of the garden, as food for larger creatures and also as re-cycling agents, but only three major groups are likely to be noticed by the gardener. These are the annelids or earthworms, the molluscs (slugs and snails), and the arthropods. The latter are by far the largest of all animal groups, containing insects, spiders, centipedes, millipedes and woodlice. Most of these small animals will find their way into your garden unaided.