Native to the North Atlantic coast of North America from Cape Cod, Massachusetts to northern Florida. The knobbed whelk lives subtidally and is migratory, alternating between deep and shallow water, depending on the time of year. During the weather extremes of the summer and winter months, these sea snails live in deep water, at depths of up to 48 m. In the milder weather of the spring and fall they live in shallow water, on near-shore or intertidal mud flats and sand flats. On the shallow-water mud flats whelks prey on oysters, clams, and other marine bivalves.