Text Size: A  A  A

Knobbed Whelk

Busycon carica

Knobbed whelks measure 5 to 9 inches in length. Their shell color varies over geographic locations: their outer shell ranges from grayish white to tan, while their inner shell ranges from pale yellow to orange. (sandy richard/Flickr)
{photos} {photo} {title} - {description} {/photo} {/photos}
Knobbed whelks measure 5 to 9 inches in length. Their shell color varies over geographic locations: their outer shell ranges from grayish white to tan, while their inner shell ranges from pale yellow to orange. (sandy richard/Flickr)

Knobbed whelks are marine gastropods that live in tidal estuaries along the Atlantic coast. Their spiral shells can range in color from grayish white to tan.

Appearance:

  • Adults measure five to nine inches in length
  • Females grow larger than males
  • Whorled or spiral shell has low knobs or spines on shoulder
  • Shell opening is located on the right side
  • Shell color varies over geographic locations: outer shell ranges from grayish white to tan, while inner shell ranges from pale yellow to orange
  • Hard plate called the operculum acts like a trap door when the snail retracts into its shell
  • Body of snail is divided into head, abdomen and foot
  • Two pairs of tentacles are located on its head: one senses light, while the other is used for touch and smell

Habitat:

  • Lives in tidal estuaries
  • Commonly found in shallow waters, but can be found offshore in depths up to 150 feet
  • Often congregate on oyster reefs and clam beds to feed on the bivalves

Range:

  • Can be found along the Atlantic coast from Massachusetts to Florida

Feeding:

  • Feeds on clams, oysters, mussels and other bivalves
  • Uses foot to hold prey while lip of shell chips and pries at the bivalve. Once a big enough hole has opened, the snail inserts its foot and begins to feed

Predators:

  • Predators include crabs, sea stars and urchins

Reproduction and Life Cycle:

  • Grows by producing turns and whorls in its shell around a central axis
  • Female lays a string of eggs in deep water twice a year, usually from September to October and April to May
  • Strings of eggs are anchored on one end to the sand and consist of up to 40 capsules, with each capsule containing up to 100 fertilized eggs
  • Eggs develop slowly and hatch in three to 13 months
  • Adults are thought to start out as males and change into females as they age, which could explain why females are almost always larger than males

Other Facts:

  • Knobbed whelks have been in existence for more than 30 million years.
  • Knobbed whelks are the state shell of both New Jersey and Georgia.
  • Knobbed whelks are fished for their meat and sold in the tourist trade as ornamentals.

Sources and Additional Information:




Click tabs to swap between type and habitat.

410 Severn Avenue / Suite 112
Annapolis, Maryland 21403
Tel: (800) YOUR-BAY / Fax: (410) 267-5777
Directions to the Bay Program Office
Terms of Use | Privacy Policy
©2012 Chesapeake Bay Program | All Rights Reserved