In this month’s Manx Wildlife Trust article about the biodiversity of the little critters in the island we are moving away from insects to look at earth worms.

Earthworms are incredibly beneficial to the environment improving soil structure by dragging down organic matter, mixing soil and creating tunnels that improve drainage.

Worm casts are so rich in nutrients that they can contain up to 40 per cent more beneficial humus than the top 23cm of soil.

Earthworms belong to the group Oligochaetes, meaning ‘few bristles’ and there are 31 species of earthworm in the UK, of which a typical garden contains about 16 species.

Earthworms are land based and their skin is permeable meaning that they need a moist environment to prevent drying out.

Different species of earthworms have different needs, some earthworm species live in compost, some live in permanent burrows deep down in the soil, while others live in the middle ground making a complex network of tunnels.

An earthworm is basically a muscular tube wrapped around a digestive system, its body is divided into segments, the first segment contains the mouth with a fleshy, muscular lobe on the top.

All the other segments have eight retractable bristles which the earthworm uses to grip surfaces as it moves along.

Have you heard about the fact that earthworms have five pairs of hearts?

These are more like a thickening of the blood vessels in its body and not chambered like human hearts.

Earthworms also have a crop like birds! It’s a sack-like structure in their digestive systems followed by a gizzard which is hard and capable of grinding down their food.

The life cycle of an earthworm starts with an egg in which a young earthworm develops until it is ready to hatch.

The eggs are wrapped in a cocoon like structure and the number of eggs in each cocoon varies between species with 20 eggs maximum.

Juvenile worms can be easily spotted as they are missing the saddle part, the broader lighter coloured ring on the body. One of the ways to classify earthworms is where they live in the soil: is it deep (anecic) or does it even live in leaf litter (epigeic)?

Here are some clues as to the type you are looking at. Anecic species are large and dark coloured at the head end (red or brown) with paler tails. Epigeic earthworms are often bright red or reddy-brown in colour, but they are not stripy.

If you have a compost heap then a different sort of worm will inhabit it, tending to be bright red in colour and stripy. They are often called ‘tiger worms’.

Given how good worms are for your garden, how can you attract more?

Try providing rotting organic material like manure or compost which is the ideal food for worms.

Collect fallen leaves from your garden and bury them into the soil.

Add a layer of grass clippings on top of the soil, it provides a protective layer against natural predators like birds and protects worms from the sun. Finally, don’t use pesticides. Worms’ permeable skin makes them very sensitive to changes in soil. Pesticides can be absorbed via their delicate skin, burning them, and even killing them.

• If you have enjoyed these articles on our invertebrates why not come along to one of our Invertebrate group meetings and join like minded people?

Details of the dates and events can be found on the Manx Wildlife Trust website mwt.im