Mistaken Identities: Whelks vs. Conchs

What's in a name? When it comes to marine snails, things can get a bit confusing. If you've ever looked at the shells of the snails in our Living Seashore touchpool and thought they were conchs, you're not alone. But the snails we find in the mid-Atlantic region are busycon whelks and belong to a different branch of the snail family tree. Busycon whelks, like the channeled whelk or knobbed whelk, differ in a lot of ways from the true conchs (pronounced "conks") you might encounter in Florida or the Caribbean. Let's take a closer look!

Other Differences

Differences in shell and aperture shape, siphonal canals and eyes are some of the easiest ways to tell whelks and conchs apart. There are a few more, too.

Range

While busycon whelks and true conchs are both found in Florida and the Gulf of Mexico, whelks can tolerate cooler waters; hence, we find them along the Atlantic coast as far north as Cape Cod. True conchs require warmer water, so they are found in sub-tropical and tropical areas in the Atlantic and Indo-Pacific. Aside from an invasive population of channeled whelk in San Francisco Bay, no other busycon whelks are found in the Pacific.

Diet

Whelks are predators and scavengers. When they bring water over their gills, the water first hits the whelk's "nose," which helps it track animals' scents. They typically prey on other mollusks, mainly bivalves. A whelk will either chip open the shells of its prey or use its muscular foot to pry them apart. Then, it uses its radula, a tooth-lined ribbon similar to a tongue, to scrape out its meal.

Conchs, on the other hand, are herbivorous. They scrape their radulas over algae attached to hard surfaces until the algae comes free.

Egg Cases vs. Egg Mats

Whelks hatch from protective egg cases. The cases look like strings lined with small leathery pouches. Each pouch can hold dozens of whelk babies that look like miniature versions of their adult forms when hatched.

Unlike whelks, conchs will lay egg masses on the sea floor made up of strands of eggs smaller than sand grains. They'll hatch after a few days and must fend for themselves among all the other plankton.