Knobbed whelk
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| Busycon carica (Gmelin, 1791) |
The knobbed whelk, Busycon carica, is the second largest species of whelk, ranging up to 12 in (305 mm). The knobbed whelk is a marine invertebrate univalve. Additionally, the knobbed whelk is simultaneously a mollusk, a gastropod, and a marine snail. Knobbed whelks are native to the North Atlantic coast of North America from Cape Cod, Massachusetts to northern Florida. The knobbed whelk is common along the Georgia coast and is the state sea shell.
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[edit] Anatomy
The knobbed whelk has a soft body encased in a hard shell.
Body
The soft body is comprised of the head, the visceral mass, and the foot (which is small). The knobbed whelk has two pairs of tentacles on the head. The larger pair each have a light-sensitive eyespot. The smaller pair of tentacles is used for the sense of smell and the sense of touch.
Shell The shell of the knobbed whelk is dextral, meaning that it is right-handed. If you hold the shell in front of you, with the spiral end up and the opening facing you, the opening will be on the right side. The aperture of the shell (the inside of the opening) is orange. It is the state shell of New Jersey.
[edit] Lifestyle
The knobbed whelk is subtidal (living underwater) and is migratory, alternating between deep or shallow water, depending on the time of year. The yearly migration pattern of the knobbed whelk involves two cycles. The knobbed whelk alternates between deep water of up to 26 fathoms (48 m), in the weather extremes of both the summer and winter months, and shallow water, in the intervening months. During the shallow water phase, Knobbed whelks live on near-shore or inter-tidal mud flats. It is here on these shallow-water mud flats that whelk prey on oysters, clams, and other marine bivalves found in the diet of these omnivorous marine snails. They eat bivalves by separating the shells with their own hard shell and inserting their long proboscis to retrieve the flesh of their victim. They eat using a radula, a rough tongue-like organ that has thousands of tiny denticles (tooth-like protrusions).
[edit] Reproduction
Mating and egg laying also occur during the spring and fall migration. Internally fertilized eggs are surrounded by a transparent mass of albumen, a gel like material, and are laid in protective flat, rounded egg capsules joined to form a paper-like chain of egg cases, commonly called a "Mermaid's Necklace". On average each capsule contains 0-99 eggs, with most strings having 40-160 capsules. After laying their egg cases, female knobbed whelk will bury one end of the egg case into the substrate, thus providing an anchor for the developing fertilized eggs and preventing them from washing ashore where they would dehydrate. Fertilized eggs will emerge as juvenile knobbed whelk approximately 4 mm in length.
[edit] Human action
As with conchs, the knobbed whelk is used by humans in many ways including as food in such dishes as salads (raw), burgers, fritters, and chowders. Also as with conchs, the shells can be made into a natural bugle by cutting off the tip of the spiral end to form a mouthpiece. The shell of the knobbed whelk is the state shell of Georgia and New Jersey.
