Whelks are snails that live in sea water. Their spiral shell is pale brown, though it's usually covered in algae or small barnacles. Like Periwinkles, a Whelk has a scale called an "operculum" that it closes to seal itself up inside its shell.
They have a single, large foot. They will live about 10 to 15 years.
Those Whelk who are born first in the egg bunches will often eat the unborn or just born ones.
Whelks have a good sense of smell to detect their prey. When they smell dinner, they can move about 4 inches (10 cm) a minute. To attack mussels, a Whelk will sit by a mussel, until a mussel is forced to open its shell to breathe or eat. Then, the Whelk forces its snout rapidly in, so that the shell can't be closed any, and the teeth start eating the mussel's flesh inside.
Larger Whelks, such as the Lightning Whelk, Busycon contrarium, found in warmer waters, are larger and so have a large and powerful enough foot that they can force clam shells open.
The North Atlantic Whelk (aka Buccinum undatumis) lives in the North Atlantic from Florida to Newfoundland and grows to be 3 to 6 inches (7 1/2 to 15 cm) long. It eats other shellfish, and has teeth on its tongue that it uses to bore a hole through shells.
Whelks are eaten in England, Italy and Japan; they are not eaten much in North America.
They can be gathered on shores when the tide is low, or caught by putting bait for them in traps.
They are easy to extract from their shells. Commercially, they are processed by crushing the shells, then washing the shells away. Because some shell may be stuck into the meat during crushing, a powerful "turbo washer" is used to blast that away.
Whelks can be bought pickled in jars, tinned in brine, or frozen.
To cook, boil fresh ones in shell in salted water for 10 minutes. Overcooking will toughen the meat and make it harder to extract from the shells.
Kept cool, Whelks will live for 5 to 6 days. To freeze, boil shucked whelk meat first for 7 minutes, then freeze.
"Whelk sellers also began their preparations early: the whelks were boiled, drained, then covered with more boiling water and stirred with a broom handle to clean out the mud and dirt, and also make it easier to 'worm' them -- remove the digestive tract -- without damaging the shell. Having been shaken up in cold water, they were ready to set out in little saucers, for between two and eight whelks for a penny." -- Flanders, Judith. The Victorian City. London: Atlantic Books. 2012. Page 282, talking about London in the 1850s to 1860s.