British earthworms
Earthworms are great for soil. They speed up decomposition by consuming lots of dead plant material, and their burrows help aerate the soil and let water through easily. Worm casts (faeces) are rich in recycled plant nutrients that help to maintain soil fertility.
At least 25 native species of earthworm live in the British Isles. While many exotic species have been accidentally introduced, these are generally restricted to botanical gardens and commercial greenhouses.
View some of the more common British earthworms below. Would you be able to tell them apart?
The lob worm, Lumbricus terrestris, is Britain's largest earthworm. The biggest individuals can be up to 35 centimetres in length when moving. They live in deep vertical burrows in the soil and can anchor themselves by broadening their tail to grip the sides of the burrow. Lob worms emerge at night to feed on fallen leaves and other decaying plant material. They can reach populations of 20 to 40 worms per square metre in an average garden lawn.
The black-headed worm, Aporrectodea longa, is another large species, extending up to 17 centimetres in length when moving. This species lives in permanent burrows, unlike some species which don't maintain their tunnels. They can produce piles of worm casts or faeces, sometimes more than 5 centimetres tall, around the entrance of their burrows. Black-headed worms can be moderately common (5 to 20 worms per square metre) in alkaline soils in open areas such as gardens, grassland and cultivated soils.
The green worm, Allolobophora chlorotica, occurs in two different colour morphs, a muddy greenish yellowy colour, and a pale grey colour. This small to medium-sized species can be 8 centimetres in length when moving, and can produce copious amounts of yellow fluid from pores along its body when disturbed. The green worm is widely distributed and is often the most numerous earthworm in all but the most acid of habitats.
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