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Northern whelk (Buccinum undatum)
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In North America, the common name whelk refers to several species of large, usually edible Busycon snails, marine gastropod mollusks in the family Melongenidae.
For information about the common European and northern Atlantic edible whelk, please see Buccinum undatum.
For information on various other marine snails which are sometimes known as whelks, please see articles on the taxonomic family to which they belong, see below.
In the British Isles and the Netherlands, where the word "whelk" seems to have originated, the word means Buccinum undatum and several related species in the family Buccinidae.
In some islands in the Caribbean, such as Saint Kitts and Nevis, the name whelks or "wilks" is used for a large edible top shell, Cittarium pica, also known as the magpie, or West Indian top shell, which is in the family Trochidae.
In the USA, a problematic introduced species is known as "Veined rapa whelk" or "Asian rapa whelk" (Rapana venosa). This species is in the family Muricidae, the murexes.
In Australia and New Zealand, species of the genus Cabestana in the family Ranellidae are called predatory whelks.
Busycon whelk shells are generally cream, light grey or tan, and in one species the shell has brown and white streaks. The shells have a long siphonal canal, and most species coil dextrally (right-handed, or in a clockwise direction).
The lightning whelk, Busycon perversum, native to the waters of the southeastern United States and the Gulf of Mexico, is unusual among gastropods in that it normally produces a sinistral (left-handed) shell. The shell shape of individual specimens varies widely in both coloration and sculpture.
The knobbed whelk, Busycon carica, is the second-largest species, ranging up to 12 in. (40.6 cm). They have tubercles (or spines) along the shoulder. Knobbed whelks eat clams. They open the clam with their hard shellstrong muscular foot and insert their long proboscis. The knobbed whelk is a common predator of the intertidal mudflats and as far offshore as 26 fathoms (48 m). The channeled whelk, Busycotypus canaliculatus, is slightly smaller than the knobbed whelk and has a smooth shell with a deep square channel which is continuous on all the whorls, just below the suture of the shell.