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Slugs
The slugs are in the class Gastropoda in the phylum Mollusca, for more pages in the phylum click below left.
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Most slugs do not have a shell, but some have a small shell or just a few grains of shell located under the mantle. |
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There are around 30 species of slug un the U.K. On the right is Arion sp. The slug body consists almost entirely of the foot. They breathe through the pneumostome, which can be clearly seen below left, and in the drawing above. Probably the most common British slug is Agriolimax reticulatus, the netted slug or grey field slug. It is a pale buff or cream colour with brown blotches, and has milky-white mucus. It is the slug which does the most damage in the garden. When it is contracted its body is almost dome-shaped. It usually mates on the soil surface early in the morning or late in the evening. Then between 5 & 20 days later the eggs are laid. There are 10 - 50 pearly-white eggs in a batch, and they are laid in the soil, under a stone or under some other suitable surface. The eggs laying nearly always takes place at night. Eggs can be laid throughout the year, but tend to be rarer and fewer in number during the winter. Several batches of eggs can be laid from one mating, but the first batch contains the most eggs, and the number decreases with each following batch. The time taken before the eggs hatch depends largely on |
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temperature - around a month being the average. The young slugs are just smaller versions of the parent, and reach maturity after 3 months to a year. The average life span is around 18 months. And as gardeners will know, it feed on healthy and decaying plants. On the left is Arion ater, in this species the young are straw coloured, not black. The adults can reach over 20 cm. There is great colour variation in these slugs with the red morph (below left) tending to be found in the south, and some authorities now say that the red slug is a different species and have given it the name of Arion rufus. The photograph on the left was taken in north-east Scotland, whereas the one below that was taken in north-east France. Studies have shown that the dark morph is more common in higher altitudes, lower temperatures and in higher humidity.
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Gardeners may want to read this sitting down. One keen Hertfordshire gardener spent 30 minutes every week removing slugs from his garden. In one year he removed over 16 000 of them. The next year they were just as abundant. However although there are 30 species in the U. K., only 4 species do any real damage to living plants. |
On the right and below is Limax maximus, the great grey slug. The colouring is variable. It can be as long as 20 cm. On the left the pneumostome can be clearly seen. Below the keel that runs up around a third of the body from the tail end can be seen. It has a curious mating ritual. Two slugs circle each other then climb a tree, shrub or some structure where they can crawl out. Then they attach a thread of mucus to the branch or overhang and descend on this thread |
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of mucus to mate in mid air. Once mating has finished both slugs descend to the ground on the mucus thread. Mating tends to take place at night. |
![[]](http://m3.moostik.net/img/?pseudo=bumblebeepages&cpt=ISlugs&option=invisible)