is found along the Eastern shore of the United States from the coast of Florida to Massachusetts Bay. can also be found along the coast of Great Britain. (Pratt, 1916 ; Nichols & Cooke, 1979 ; JNCC, 1998)
usually dwell on rocks or in the sand along the coast and in bays. (Nichols & Cooke, 1979) is found anywhere oysters flourish. They are most abundent in intertidal zones and shallow water areas including estuaries, marshes, and bays. especially enjoys these waters when there is a relatively high salinity content. Usually, the greater the salinity content the more this species will thrive at a specific location. (Beal, 1993 ; NOAA, 2000)
- Aquatic Biomes
is about 25mm long and 15mm wide. Its flesh is of a gray or yellowish color with brown spiral stripes. Its shell resembles that of the common Ocenebra but is smaller, darker, and less ridged. Its shell is fusiform and has a rough texture created by an average of 12 ridges running longitudinal along the shell. The shell is also characterized by 5 to 6 raised whorls. The lip of the shell typically has between 2 and 6 teeth and is scalloped along with a short aperture with a canal. The species seems to be monomorphic and there is no difference in appearance depending upon the season. There also seems to be no reported or observed polymorphisms. Young members of the species seem to only differ from adults in relative size including length and mass. (Pratt, 1916 ; Nichols & Cooke, 1979)
The breeding season begins once the water temperature drops down into the 20s C and remains there for a week. The eggs are fertilized and deposited between rocks or on the floor of the ocean. The eggs are usually 240 microns in diameter. When the eggs are deposited with an albuminus substance that provides nourishment for the development of embryos. The cleavage of the egg is unequal and spiral with large polar lobes. The hatching embryo produces an enzyme that dissolves the protective sack. The average time it takes for an embryo to develop from fertilization to hatching is 40 days. The embryonic development itself is related to that of other gastropods. The veliger is formed at an early stage of development. Next, the foot appears and is formed before the blastopore closes. At this point, both the velum and the shell are well developed. The anus and intestinal track are late in forming. The velum is lost and the young snail emerges as a well-formed snail. (Costello & Henley, 2000)
Food usually consists of oysters and other mollusks. This makesa carnivore. It prefers to prey upon smaller softer shelled oysters, which are much easier to penetrate and eat. They are usually stationary or somewhat mobile filter feeders that remain in set stationary breeding or living beds located on the floor of the shoreline. crawls over the beds finding small oysters. It then grips the shell with its foot, which secretes a softening agent and uses its drill, called a radula, in a mechanical process to break through the prey's shell. Once this occurs inserts its proboscis into the oyster, which then secretes a muscle relaxer into the prey causing the oyster to open exposing the animal inside. (Morton, 1958 ; Buchsbaum & Pearse, 1987 ; Nichols & Cooke, 1979)
After drilled, a total of one fourth of the oyster's tissue remains inside. This tissue consists of the adductor muscle, various soft parts, and the gills. The muscle destruction of the oysters caused by the drill was found to range from none to total destruction. However, it was found that in 90% of the oysters studied, at least half of the adductor muscle was destroyed. The oyster drills exhibited a clear preference when eating consisting of various soft tissues, the gills, and the adductor muscle allowing the oyster drills to eat as long as possible on one oyster before it gapes allowing other predators to feed upon it.drills the oysters through the central portion of the valve and not at the margin of the valves. (Chapman, 1955)
Economic Importance for Humans: Negative
is a natural predator for Eastern Oysters as well as other mollusks. It especially prefers soft-shelled young oysters and tends to eat numerous small meals instead of one larger one. Therefore, the species can become a real pest in commercial oyster areas killing off large numbers of young oysters reducing the amount of harvestable oysters in the succeeding years. This carnivore kills on average 60% or more of the seed crop annually. (Nichols & Cooke, 1979 ; Buchsbaum & Pearse, 1987 ; Gosner, 1979)
Global warming is having a negative affect on numerous estuaries and wetlands located around the world. Global warming is causing the sea level to rise, which is causing a number of wetlands to be immersed in salt water causing a rapid decline in the number of estuaries. Not only are the wetlands being immersed in water causing the plant life to die but also it is carrying the salt water further and further inland raising the salinity content of the neighboring waters. Furthermore, increased drought frequencies caused by global warming will also cause the salinity content to rise. This is advantageous toand other predatory gastropods who enjoy water with a high salinity content. As global warming increases, their populations are expected to increase while the number of oysters, clams, and other bivalves is expected to decrease in the near future. ( EPA, 2001)
Bradley Williams (author), Western Maryland College, Louise a. Paquin (editor), Western Maryland College.
- Atlantic Ocean
the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.
- bilateral symmetry
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
the nearshore aquatic habitats near a coast, or shoreline.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
- native range
the area in which the animal is naturally found, the region in which it is endemic.
Beal, B. 1993. Major Predators of Cultured Shellfish. Northeastern Regional Aquaculture Center, 180: 4.
Buchsbaum, R., M. Buchsbaum, J. Pearse, V. Pearse. 1987. Animals Without Backbones Third Edition. Chicago: The University of Chicago Press.
Chapman, C. 1955. Feeding Habits of Southern Oyster Drill. Proc. National Shellfish Association, 47: 169-176.
Costello, D., C. Henley. "Methods For Obtaining And Handling Marine Eggs And Embryos" (On-line). Accessed February 24, 2001 at http://database.mbl.edu/Costello/find.taf?function=BB&ID=67.
EPA, April 6, 2001. "Global Warming Coastal Fisheries" (On-line). Accessed May 4, 2001 at http://www.epa.gov/globalwarming/impacts/fisheries/coastal.html.
Gosner, K. 1978. A Field Guide to the Atlantic Seashore. Boston: Houghton Mifflin Company.
JNCC, 1998. "Urosalpinx cinerea" (On-line). Accessed May 4, 2001 at http://jncc.gov.uk/marine/dns/d2_2_6_2.htm.
NOAA, C. September 31, 2000. "The American Oyster" (On-line). Accessed May 4, 2001 at http://www.csc.noaa.gov/acebasin/specgal/oyster.htm.
Nichols, D., J. Cooke. 1971. The Oxford Book Of Invertebrates. New York: Oxford University Press.
Pearse, V., J. Pearse, M. Buchsbaum, R. Buchsbaum. 1987. Living Invertebrates. Pacific Grove, California: The Boxwood Press.
Pratt, H. 1916. A Manual Of The Common Invertebrate Animals. Chicago: A.C. McClurg & CO..