Whelks are sea animals that look rather like land snails, as they move about on a broad fleshy foot a large shell on their backs . Unlike land snails and other sea snails such as periwinkles they have a siphon or tube running out from the part of the body known as the mantle cavity to draw in water for breathing.
As a result they are able to bury themselves partly in sand and plough through it, keeping the mouth of the siphon above the surface in order to breathe. There are several kinds of whelks round the coasts of great Britain . The dog whelk with a shell an inch or more long eats acorn , barnacles , mussels and other molluscs , boring through the shell with its rasp like tongue and sucking out the soft body inside. The large common whelk which has a rough , grey shell , preys on oysters . Its flesh is used as bait by fishermen and it is also sold from stalls for eating .Each capsule contains many eggs which hatch out before the capsule is opened. Inside the capsule, the bigger and stronger young dog whelks eat many of there brothers and sisters so that very few finally reach the open sea.
