Neptunea antiqua, common name the red whelk, is a species of Northeast Atlantic sea snail, a marine gastropod mollusk in the family Buccinidae, the true whelks.
N. antiqua resembles Buccinum undatum (common whelk). It can grow to a length of 20cm (10inches),[1] although most specimens only reach half that size.[2] It is the largest marine snail in parts of its range.[1]
N. antiqua is found in the Northeast Atlantic along cold-temperate European coasts, ranging from the low water mark[3] to a depth of 1200m (3,900feet).[2]
N. antiqua is primarily a scavenger, although it has been recorded attacking and eating some living polychaete species.[3] Unlike several of its more predatory relatives, experiments have shown that even hungry N. antiqua are not attracted to living undamaged mussels.[3]
N. antiqua contains tetramethylammonium salts (most likely the chloride) in its tissues, and has been the source of non-lethal human poisoning.[4]