whelk, large marine gastropod snail found in temperate waters. The whelk is sometimes eaten, but when food is plentiful, fishermen frequently use it for bait. Whelks are scavengers and carnivores, equipped with an extensible proboscis, tipped with a filelike radula, with which they bore holes through the shells of crabs and lobsters, and a large, muscular foot with which they hold their victims. The thick-lipped, spiral shell has an uneven surface with many protuberances. The knobbed whelk, the largest species, ranging up to 16 in. (40.6 cm), and the channeled whelk, slightly smaller, are both found south of Cape Cod, Mass. In summer the strings of pale, disk-shaped egg cases are common along the shore. The whelk is sometimes mistakenly called conch. Whelks are classified in the phylum Mollusca, class Gastropoda, order Neogastropoda.