Animal Diversity Web

Geographic Range

The waved whelk, or common northern whelk, can be found in the North Atlantic along the coastline of North America from New Jersey northward, the coastline of Greenland, the coastline of Europe from France northward, the coastlines of Norway, the British Isles, Iceland, and the coastlines of some islands in the Arctic Ocean (George and George 1979, Grzimek 1972, Ghiselin 2000).

• Biogeographic Regions
• arctic ocean
  • native
• atlantic ocean
  • native

Habitat

Waved whelks occupy coastlines within the range described above from the tide level to 180 meters depth. They live in the mud and sand of these areas on the ocean floor (Ghiselin 2000, George-George 1979, Grzimek 1972, Anderson 1988).

• Aquatic Biomes
• coastal

Physical Description

The marbled body of the whelk is encased in a calcified shell, which ranges from 6-10 cm in length. The shell is spiraled, and lacks the nacreous surface layer of some other gastropods. The body is composed of three basic parts: the foot, the head, and a visceral mass. The foot extends from the shell next to the head and is used for locomotion and grasping prey or a substrate when feeding on algae. The head includes a mouth, from which the radula, an elongated tongue-like apparatus bearing three central teeth and two rows of transverse teeth, is extended for feeding. There are also two cephalic tentacles which have some tactile sensation. These tentacles and the osphradia, a structure that does not emerge from the shell but is positioned at the end of a siphon pointing in the direction of the current, have chemoreceptors which aid in scavenging. Whelks are either male or female, with gonads positioned deep within the shell behind the body because of the torsion of the spiral shell. Males of the species have a penis for sperm transfer (George and George 1979, Grzimek 1972, Brusca 1990).

• Other Physical Features
• ectothermic
• bilateral symmetry

Reproduction

Sexes are separate, and the male has a penis which transfers sperm to the female, where internal fertilization occurs. There are two types of sperm produced by the male whelk. The first is the viable euspermatozoa, which are the functional gametes that will unite with the egg in the reproductive tract of the female. Accompanying these are paraspermatozoa, which have multiple external tails and help to control and assist in the movement of the viable sperm, as well as provide them with nutrients. After fertilized eggs emerge from the oviduct, they are coated in mucus and approximately 1000 are contained in a flexible capsule. These capsules are then released into piles. Of the 1000 eggs in a capsule, only about 10 undergo full development, the rest providing nutrition. Snails hatch from these capsules fully developed (Anderson 1988, Grzimek 1972).

Behavior

This species actively seeks out is living prey and carrion, using chemoreceptors for sensing and the foot for locomotion. When disturbed it may withdraw into its shell and use the foot's hard surface, called the operculum, to seal the shells aperture (Ghiselin 2000).

Food Habits

The waved whelk is a carnivore, and feeds on crabs, polychaete worms, bivalves, and dead organisms. Water enters the siphon which is pointed in the direction of the current and the osphridia's chemoreceptors detect for prey. The whelk moves to the prey using its foot, and uses it to grasp the shell in the case of a crab or bivalve. The radula is extended from the mouth and if the prey has a shell, the radula's teeth are used to drill a beveled hole through which the radula can extract the body matter. Radular teeth of whelks are solid and do not contain poison as in the case of cones, but the tongue may confer a secreted acidic mucus to the shell that is being bored. Digestion is primarily extracellular and takes place within a digestive gland at the end of a long esophagus that empties into a stomach (Anderson 1988, Alexander 1979, Brusca 1990, Ghiselin 2000).

Economic Importance for Humans: Positive

On the coast of North America fishermen often use the body of the whelk without the shell as bait for cod. In the past fishermen have been known to use the egg capsule of the whelk as "sea soap" to clean their hands. In Europe and Scandinavia the waved whelk serves as a food source for humans. We also receive the indirect benefit of the scavenging habits of the whelk in the disposal of carrion on the ocean floor (Grzinek 1972, Brusca 1990).

Economic Importance for Humans: Negative

N/A

Conservation Status

The northern whelk is found readily in along the coasts of its geographic range in large numbers, especially in North America, probably due in part to its excellent and complex reproductive adaptations (Anderson 1988, Ghiselin 2000, U.S. Fish and Wildlife 2000, Sea World Education Dep. 2000).

• IUCN Red List

  No special status

• US Federal List

  No special status

• CITES

  No special status

Other Comments

One interesting note is that hermit crabs frequently use the empty shells of whelks (Grzinek 1972).

Contributors

Zech Carter (author), Southwestern University, Stephanie Fabritius (editor), Southwestern University.

References

2000. "Endangered Species" (On-line). Accessed April 16, 2000 at http://www.seaworld.org/endangered_species/escont.html.

2000. "U.S. Listed (Endangered) Invertebrate Animal Species Indexed by Land Region and Status" (On-line). Accessed April 16, 2000 at http://endangered.fws.gov/Isppinfo.html.

Alexander, R. 1979. The Invertebrates. Great Britain: Cambridge University Press.

Anderson, D. 1988. Phylum Mollusca. Pp. 123-139 in Invertebrate Zoology. Australia: Oxford University Press.

Brusca, R. 1990. Invertebrates. USA: Sinauer Associates.

George, D., J. George. 1979. Marine Life. New York: John Wiley and Sons.

Ghiselin, D. 2000. "Gastropod and Whelk" (On-line). Accessed April 15, 2000 at http://encarta.msn.com.

Grzimek, B. 1972. The Gastropods. Pp. 87-88 in B Grzimek, ed. Grzimek's Animal Life Encyclopedia. London: Litton World Trade Corporation.