Species Description: Busycon contrarium is a large gastropod in the family Melongidae. The shell of the lightning whelk is usually very recognizable because it spirals toward the left instead of the right like other gastropod shells. Juvenile shells have lightning bolt-shaped stripes on the shell, hence the common name. The interior of juvenile shells can be white, yellow or pale blue. Adults, on the other hand, are gray with a few vertical violet-brown streaks (Magalhaes 1948). The aperature of the adult shells can vary from white, pale yellow to orange or bright red.
Regional Occurrence: Busycon contrarium occurs along the North American coastline from New Jersey to Texas. They are commonly encountered in estuaries, creeks and around oyster bars.
IRL Distribution: The lightning whelk has been reported from the Indian River Lagoon (Boudreaux et al. 2006).
Age, Size, Lifespan: Busycon contrarium grow up to 41 cm in length (Magalhaes 1948).
Abundance: The lightning whelk is less common than other members in the genus Busycon. In Beaufort, North Carolina, only one individual of B. contrarium was collected for every 33 individuals of its congener B. carica (Magalhaes 1948). Similar numbers are reported from other regions of the Atlantic coast of the United States.
Migration: Busycon spp. migrate from deep to shallow waters in times of reproduction and low food supply (Magalhaes 1948).
Reproduction: Busycon contrarium has separate sexes. Reproduction is internal and copulation occurs in late autumn to early winter. Females lay long strings of disc-shaped egg capsules that measure up to 86 cm in length and 3 cm wide in early spring (Kent 1983, Ruppert and Fox 1988). The string of eggs is anchored to the sand and the capsules break loose when the eggs hatch at the beginning of May.
Embryology: Fertilized eggs of Busycon spp. develop slowly and hatch in approximately 3 to 13 months. They emerge as juveniles, measuring nearly 4 mm in length, that crawl along the bottom (Magalhaes 1948).
Temperature: Feeding rates and crawling speeds of Busycon contrarium decrease as seawater temperatures increase or decrease above or below the intermediate temperatures of 25-28°C (Kent 1983). Growth ceases when temperatures fall below 20°C.
Salinity: There are no specific studies addressing the salinity tolerance of Busycon contrarium.
Trophic Mode: Lightning whelks are carnivorous and prey on bivalves such as clams, usually eating one a month. They force open the shells of the bivalve with their large foot and hold it open by the edge of their own shell. Once the bivalve is open, the whelk inserts its radula and proboscis inside the clam to scrape and eat the clam meat (Ruppert and Fox 1988). Members of this genus are considered a nuisance in regions of open water fisheries because they prey upon edible molluscs.
Associated Species: The dead shells of Busycons are host to several species of Crepidula and are also often inhabited by hermit crabs and serve as substrata for oyster spat (Magalhaes 1948).
Fishery: Members in the genus Busycon are used for food and ornaments. The muscular feet of these snails are used in chowders and served as steaks (Magalhaes 1948).
Boudreax ML, Stiner JL and LJ Walters. 2006. Biodiversity of sessile and motile macrofauna on intertidal oyster reefs in Mosquito Lagoon, Florida. Journal of Shellfish Research 25:1079-1089.
ITIS Integrated Taxonomic Information System. Available online.
Kent BW 1983. Natural history observations on the busyconine whelks Busycon contrarium (Conrad) and Busycon spiratum (Lamarck). Journal of Molluscan Studies 49:37-47.
Magalhaes H 1948. An ecological study of snails of the genus Busycon at Beaufort, North Carolina. Ecological Monographs 18 (3): 379-409.
Ruppert E and R Fox. 1988. Seashore Animals of the Southeast. University of South Carolina Press 429 pp.
The Whitney Laboratory for Marine Bioscience Left Handed Whelk, Lighting Whelk (Busycon contrarium).