Slug is a common name for a terrestrial gastropod mollusc that usually has no shell (or a very small one). Slugs live both on land as well as in sea, and there is even one specie that lives in freshwater. The term slug is usually used to describe the land slugs, whereas the slugs living in sea or fresh water are usually referred to as sea and freshwater slugs respectively. Slugs are detritusvores i.e. they eat fungus and dead leaves.
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Snails are highly diversified shelled gastropods, with more than 25000 species in the world. The snails typically have coiled bodies covered with a similarly coiled shell. However the size, colour and shape of snails vary drastically among species. The snails use this coiled shell to hide in when they are alarmed. Snails mostly live in sea but some species have been located on land as well in freshwater.
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