Knobbed Whelk
Busycon carica (Gmelin, 1791)
Georgia And New Jersey State Shell
The Knobbed Whelk is fairly common on S. Hutchinson Island beaches. It's not as common as the Lihgtning and Pear whelks but I've found some small/medium sized shells. Knobby Whelks usually open on the right similar to Pear Whelks.
Knobbed Whelk (about 2.5") S. Hutchinson Island December 2020
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Indian River Lagoon Species Inventory
Species Name: Busycon carica Gmelin, 1791
Common Name: Knobbed Whelk
Synonymy: Fusus lamellosus Emmons, E., 1858
TAXONOMY
Kingdom Phylum/Division Class: Order: Family: Genus:
Animalia Mollusca Gastropoda Neogatropoda Melongenidae Busycon
Species Description
Busycon caricais a member of the family Melongenidae and one of roughly fourteen known species of the subfamily Bucyconinae. Members of the genus Busycon are the largest marine gastropods along the eastern coast of the United States (Ram 1977). Juvenile whelks have small beads on their shells, while adult whelk shells are thick with spines on the shoulder. Knobbed whelk shells are right-handed and have a long siphonal canal. The outer shell is grayish white to tan and may have some dark brown streaks. The brown streaks are more prominent in juvenile shells. The inner shell ranges in colors from pale yellow to orange and even dark red.
HABITAT AND DISTRIBUTION
Regional Occurrence
Busycon caricaoccur on the coast of the Atlantic from Cape Cod, Massachusetts to Cape Canaveral, Florida. Knobbed whelks are mainly found in estuaries, bays and shallow shelf waters (Magalhaes 1948). They occur at depths of 1 to 50 meters.
IRL Distribution
The knobbed whelk occurs in the Indian River Lagoon, but is not common.
LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan
Knobbed whelks reach maturity in about three to five years. Whelks are considered to be protandric hermaphrodites initially functioning as males and changing into females as they age (Castagna and Kraeuter 1994, Anderson 2005). Adult females are generally larger than adult males of the same age. Adult whelks may be as long as 30.5 cm (Magalhaes 1948).
Abundance
Busycon caricais a common species of the shallow shelf ecosystem and estuaries especially in South Carolina and Georgia. The density of the knobbed whelk in Beaufort, North Carolina was estimated to be 1 individual per 79 2 during non-reproductive seasons (Magalhaes 1948).
Migration
Busycon spp. migrate from deep to shallow waters in times of reproduction and low food supply (Magalhaes 1948).
Locomotion
Knobbed whelks glide along or just beneath the sand on the ocean floor (Magalhaes 1948).
Reproduction
Male and female Busycon caricamate by coupling. The reproductive season for the knobbed whelk in Beaufort, North Carolina is reported to begin in March and lasts through September (Magalhaes 1948). In South Carolina, B. carica reproduces during the fall and spring (Anderson 2005). After fertilization occurs the female lays a string of eggs in deep water and anchors the string to the sand by one end. The capsules of B. carica are wide with two smooth surfaces resembling book covers (Magalhaes 1948, Ram 1977). These strings of eggs consist of up to 40 pouches, with each pouch containing up to 100 fertilized eggs. Field studies have shown that egg strings are laid in the fall on tidal and intertidal flats and over winter to hatch in the spring (Castagna and Kraeuter 1994).
Embryology
The fertilized eggs of the knobbed whelk develop slowly and hatch in approximately 3 to 13 months (Anderson 2005). The larva emerge as juveniles and measure approximately 4 mm in length. Under laboratory conditions, the shells of the hatchling were observed to grow 1.5 mm in 22 days (Magalhaes 1948).
PHYSICAL TOLERANCES
Temperature
There are no specific studies addressing the temperature tolerance of Busycon carica.
Salinity
There are no specific studies addressing the salinity tolerance of Busycon carica.
COMMUNITY ECOLOGY
Trophic Mode
Busycon caricais a carnivorous gastropod that feeds on bivalves. They use the lip of their shell to break off and force open the valves of their prey by holding it with its foot. Slow chipping continues until there is an opening that allows the whelk to lodge its shell between the bivalves's valves and then enter its foot to begin feeding. The feeding process generally results in damage to the whelks shell which causes limited growth in adults since a lot of energy is used to repair their shell. Some bay men from estuaries along the New Jersey and New York coasts suggest that B. carica cause severe predation of oysters (Carriker 1951).
Associated Species
The deal shells of Busycons are host to several species of Crepidula and oyster spats and often inhabited by hermit crabs (Magalhaes 1948).
ADDITIONAL INFORMATION
Fishery
Knobbed whelks are mainly used for their meat. The whelk trawl fishery off the South Carolina coast became an important fishery during 1977 and the spring of 1978 during periodic closure of the shrimp season (Anderson et al. 1985). In Delaware, the whelk dredge landings were 18.5 million tons of meat from 1994-2000 and increased to 241.6 million tons from 2001-2004 (Bruce 2006). Members in this genus are also sold in the tourist trade as ornamentals (Magalhaes 1948).
REFERENCES
Anderson WD. 2005 Busycon carica. Comprehensive Wildlife Conservation Strategy; SC Department of Natural Resources. Available online as a pdf file.
Anderson WD, Eversole AG, Anderson BA and KB Van Sant. 1985. A biological evaluation of the knobbed whelk fishery in South Carolina. National Marine Fisheries Service Publication. 2-392-R 76 pp.
Bruce DG. 2006. The whelk dredge fishery of Delaware. Journal of Shellfish Research 25:1-13.
Carriker MR. 1951. Observations on the penetration of tightly closing bivalves by Busycon and other predators. Ecology. 32(1):73-83.
Castagna M and JN Kraeuter. 1994. Age, growth rate, sexual dimorphism and fecundity of knobbed whelk Busycon carica(Gmelin,1791) in a western Mid-Atlantic lagoon system, Virginia. Journal of Shellfish Research. 2(2): 581-585.
The Georgia Shell Club Whelk Page.
Hardy's Internet Guide to Marine Gastropods. Available online.
Magalhaes H. 1948. An ecological study of the genus Busycon at Beaufort, North Carolina. Ecological Monographs. 18(3): 377-409.
Ram JL. 1977. Hormonal control of reproduction in Busycon: Laying of egg capsules caused by nervous system extracts. Marine Biological Laboratory. Biol. Bull., 152: 221-232.
Report by: Melany P. Puglisi, Smithsonian Marine Station
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Knobbed whelk
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Knobbed whelk
Busycon carica.jpg
A live individual of Busycon carica at low tide at Bethany Beach, Delaware
Scientific classification edit
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Subclass: Caenogastropoda
Order: Neogastropoda
Family: Buccinidae
Genus: Busycon
Species: B. carica
Binomial name
Busycon carica
(Gmelin, 1791) [1]
The knobbed whelk (Busycon carica) is a species of very large predatory sea snail, or in the US, a whelk, a marine gastropod mollusk in the family Busyconidae, the busycon whelks.
The knobbed whelk is the second largest species of busycon whelk, ranging in size up to 12 in (305 mm).[2]
Contents
1 Distribution
2 Shell description
3 Life habits
4 Reproduction
5 Human use
6 References
Distribution
Knobbed whelks are native to the North Atlantic coast of North America from Cape Cod, Massachusetts to northern Florida. This species is common along the Georgia coast. It is the state shell of New Jersey and Georgia.
Shell description
Knobbed whelk shells
Busycon carica ssp. eliceans
The shell of most knobbed whelks is dextral, meaning that it is right-handed. If the shell is held in front of the viewer, with the spiral end up and the opening facing the viewer, the opening will be on the animal's right side. The shell is thick and strong and has six clockwise coils. The surface is sculpted with fine striations and there is a ring of knob-like projections protruding from the widest part of the coil. The color is ivory or pale gray, and the large aperture (the inside of the opening) is orange. The canal inside is wide and the entrance can be closed by a horny oval operculum.[3][4]
Life habits
The knobbed whelk lives subtidally and is migratory, alternating between deep and shallow water, depending on the time of year.
During the weather extremes of the summer and winter months, these sea snails live in deep water, at depths of up to 48 m. In the milder weather of the spring and fall they live in shallow water, on near-shore or intertidal mud flats and sand flats.
On the shallow-water mud flats whelks prey on oysters, clams, and other marine bivalves. They wedge a bivalve open using the edge of their shell, and insert their long proboscis to eat the flesh of their victim. They rasp at the flesh using their radula, a rough tongue-like organ that has thousands of tiny denticles (tooth-like protrusions).
Reproduction
Whelk egg case
Mating and egg laying occur during the spring and fall migration. Internally fertilized eggs are surrounded by a transparent mass of albumen, a gel-like material, and are laid in protective flat, rounded egg capsules joined to form a paper-like chain of egg cases, commonly called a "Mermaid's Necklace". On average each capsule contains 0-99 eggs, with most strings having 40-160 capsules. After laying their egg cases, female knobbed whelk will bury one end of the egg case into the substrate, thus providing an anchor for the developing fertilized eggs and preventing the string of egg cases from washing ashore where it would dehydrate. Fertilized eggs develop in the capsules. Young emerge with a shell approximately 2–4 mm in length.
Young are preyed upon by crustaceans, horseshoe crabs, and fish, primarily drum species. Adult whelks are eaten by loggerhead sea turtles.
Human use
As with conchs, the knobbed whelk is used by humans as food in such dishes as salads (raw), burgers, fritters, and chowders.
As is also true of conch shells, the shell of the knobbed whelk can be made into a natural bugle by cutting off the tip of the spire in order to form a mouthpiece.
Historically, American Indians used the knobbed whelk as a component in wampum, the shell beads exchanged in North America for trade.[5]
References
Busycon carica (Gmelin, 1791) World Register of Marine Species. Retrieved 2011-11-28.
Busycon carica Gmelin, 1791 Smithsonian Marine Station at Fort Pierce. Retrieved 2018-12-01.
Knobbed Whelk: Shell Money Retrieved 2011-11-28.
"Anatomy of the knobbed whelk". Archived from the original on 2005-04-02. Retrieved 2020-02-18.
White, Richard (1991). The Middle Ground. New York: Cambridge University Press. p. 97. ISBN 9781139495684.
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Looks similar to the Plio-Pleistocene Nashua Formation species (Brachysycon amoenum (Conrad, 1875). It is also known from the Waccamaw Formation and elsewhere. See Gardner (1948) USGS professional paper 199, page 292.