Channeled whelks and Knobbed whelks both inhabit Barnegat Bay

Whelks

Whelks

Whelks are large marine snails (gastropods) with spiral shells. They are both are scavengers and carnivores and travel along (or just under) the bay bottom in search of clams and other shellfish.   

Whelks grow by using their mantle to produce calcium carbonate to extend their shell around a central axis or columella, producing turns, or whorls, as they grow. A whorl is each spiral of the shell.

The final whorl, and usually the largest, is the body whorl that terminates, providing the aperture into which the snail can withdraw.

<click on any image to enlarge>

Whelks also have a separate hard, horny plate, called an operculum, which acts like a trap door when the snail withdraws into the shell. Sometimes called a “shoe,” the operculum is attached to the top of the living animal’s foot. <see lower right image>

Whelks are subtidal animals, meaning they lives only below the low tide mark. because their operculum does not tightly seal the opening of the shell it cannot survive being exposed to the air as some intertidal animals (like mussels) can.

When hunting prey, they travel along the bay bottom using their strong foot and use their nose (or proboscis) to find these buried animals by sensing the stream of water flowing out of the clam’s feeding tubes.

Once its prey is located the whelk digs down into the bay bottom to capture it.

Feeding

Method 1 - Whelks use their shell’s lip to chip and pry the valves of bivalves (i.e. clams) apart by holding it with its foot so that the ventral edges of the prey’s valves are under the outer lip of the whelk’s shell.  This is similar to using a clam knife to shuck (open) a hard clam.

Slow chipping continues until an opening occurs to allow the whelk to wedge its shell between the clam’s valves. When there is sufficient room, it extends its proboscis (with mouth at the end) to begin feeding.  

Method 2 - Another method of getting at a food source (especially if the victim is not a bivalve) is that once the prey is immobilized, the whelk extends its proboscis which is equipped with a mouth and a tooth-like radula at the end.   <click here for more radula details>

The whelk has a gland that secretes a chemical that softens calcium carbonate so the radula can efficiently be used to bore a hole in the shell of the prey. 

When the drilling process is completed, the whelk extends its proboscis into the prey and begins feeding.

Fun Fact - Whelks are often confused with Conchs - both are large marine snails similar in appearance.

Conchs live in warmer tropical waters and are herbivores feeding on vegetation.

Whelks live in more temperate (cooler) waters and are carnivores whose diet is mostly meat.

Fun Fact - Scungilli is the meat of whelks and conchs.  

The name is an Italian-American modification of the Neapolitan word, sconciglio which means the meat of a (usually edible) sea snail.

Fun Fact -  Most whelks (as well as most snails) are right handed or dextral. If the shell is held upright, with the spire up and the aperture facing the observer, then the aperture is on the right side.  The opposite, much less common, condition is sinistral, in which the aperture is on the left of the central axis. 

Knobbed whelk          Busycon carica

The knobbed whelk is an inhabitant of Barnegat Bay with the characteristics of whelks described above.

 The shell of the knobbed whelk is heavy and ornamented with strong, blunt knobs or spines around the shoulders of the larger whorls.  They can grow to about 8 to 9 inches.

Fun Fact - The knobbed whelk is the official State Shell of New Jersey. In addition, it is also the  State Shell of Georgia.

Channeled whelk          Busycotypus canaliculatus

Channeled whelks typically reach 5 to 8 inches in length. The shell is smooth and generally pear-shaped, with a large body whorl and a straight siphonal canal. Between the whorls there is a wide, deep channel at the suture, and there are often weak knobs at the shoulders of the whorls. Finely sculpted lines begin at the siphonal canal and revolve around the shell surface.

The color of the shell is typically a buff gray to light tan. The shell aperture is located on the right side, i.e. the shell of this species is almost always dextral in coiling. Left-handed or sinistral specimens occur rarely.

Channeled whelks prefer sandy, shallow, intertidal or subtidal areas, and can be common in these habitats. They tend to be nocturnal and are known to eat clams.