Species Description: The shell of Urosalpinx cinerea is knobby, having rugged whorls (turns of the shell) with rounded shoulders, usually numbering 5. Each complete turn of the Atlantic oyster drill has 9-12 vertical, rounded ribs crossed with 15 rows of thinner spiral ridges. The aperture (opening through which the snail moves in and out of the shell) of U. cinerea is oval with an open canal at the base. Shells are usually yellow sometimes orange, grey or white and occasionally bearing brown streaks. The interior of the shell can be purple, red-brown or yellow. The operculum (the plate that closes to protect the snail when it is inside its shell) can be orange or yellow-brown.
U. cinerea, a mollusk in the family Muricidae, is considered a major pest among the world's bivalve fisheries (Robinson and Dillon 2008). In colder waters, this species will be dormant throughout the winter and emerge in April to feed (Franz 1971).
Regional Occurrence: The natural range of Urosalpinx cinerea is northwestern Atlantic to southeastern Florida. The mode of development of U. cinerea naturally limits its population range (Minchin 1996). Human transport in ballast water of ships and in seed beds of its bivalve prey have introduced this voracious muricid gastropod to the Gulf of Mexico, the Pacific coast of the United States, and the eastern north Atlantic (Robinson and Dillon 2008). The Atlantic oyster drill occurs in intertidal and shallow subtidal waters in estuaries and bays to a maximum depth of approximately 15 m and is common on rocks and oyster reefs (Franz 1971).
IRL Distribution: Urosalpinx cinerea inhabits oyster reefs (Crassostrea virginica) of the Indian River Lagoon.
Age, Size, Lifespan: Urosalpinx cinerea live 5-8 years and reach sexual maturity in 2 years, when they reach approximately 16mm in length. The shell size of the Atlantic oyster drill is reported to vary among populations (Franz 1971). Populations in England are reported to be larger than the eastern Atlantic. On the Pacific coast, this gastropod is recorded to grow to 30-35 mm in length. In this same population, female specimens were recorded at larger sizes than their male counterparts. Variation in growth rate, span of time during growth, and diet may account for these observations (Franz 1971).
Abundance: Populations of the Atlantic oyster drill can be very dense, ranging between 10 - 100 individuals per square meter (Ritchoff et al. 1983).
Reproduction: Urosalpinx cinerea spawns in spring and summer. Each female attaches approximately 20-40 leathery vase-shaped egg capsules to a hard surface. The capsule is transparent and half a centimeter in height (Franz 1971, Robinson and Dillon 2008).
Embryology: Atlantic oyster drill eggs develop directly into benthic juveniles, skipping a pelagic stage (Robinson and Dillon 2008). Newly emerged juveniles migrate to their food source. In a mid-Atlantic population, first season specimens were reported to associate closely with ectoprocts (Franz 1971). Most shell growth in Urosalpinx cinerea occurs in the first two seasons before the snail matures.
Temperature: The optimal temperature for the development of the Atlantic oyster drill is reported to be 20°C (Ganaros 1958). In laboratory experiments, Urosalpinx cinerea were shown to feed optimally at 25°C, and exhibited significant decreases as the temperature increased or decreased (Hanks 1957). In addition, temperature fluctuation has a profound effect on development. When temperatures are decreased below 25°C , an increase in the number of days it takes early larvae to attain the shelled veliger stage is observed (Ganaros 1958). However, temperature fluctuations did not inhibit the ability of the larvae to attain the protoconch stage.
Salinity: Urosalpinx cinerea can live in salinities as low as 13 - 15‰. In populations of the Atlantic oyster drill collected from the James River, Virginia, mortality was observed when the salinity decreased to 9‰ (Zachary and Haven 1973). When the salinity was increased the activity of the oyster drills also increased. In laboratory experiments examining the combined effects of temperature and salinity, increased temperatures resulted in increased feeding and reproduction even at very low salinities (Manzi 1970).
Trophic Mode: The Atlantic oyster drill preys upon oysters, barnacles and other bivalves, including mussels. Young snails feed on bryozoans, ectoprocts, small snails and barnacles. In San Francisco Bay, the preferred prey is reported to be young barnacles and clams. In the mid-Atlantic, the barnacle Balanus balanoides and the mussel Mytilis edulis are the preferred prey (Franz 1971). Adults are reported to use a chemical cue released from the prey to locate suitable feeding habitats (Ritchoff et al. 1983). In laboratory experiments with newly hatched juveniles that were not previously exposed to prey species, Urosalpinx cinerea preferentially migrated upstream toward "odors" from living barnacles.
The gastropod bores a hole through the shell of its prey with a file-like rasping organ, called a radula, and produces acidic chemical secretions from a boring gland that soften the shell. U. cinerea then inserts its proboscis to get to the prey's soft tissue (Brusca and Brusca 1990). The Atlantic oyster drill is a voracious predator, and has the potential to be one of the most destructive predators of young oysters (Ganaros 1958).
Competitors: Competitors of the ornate blue crab are other crustaceans, in particular C. sapidus and C. similis.
Invasion History: Urosalpinx cinerea is an invasive species in many parts of the world, and has been introduced to several new regions by human transport by ship and other means. It was first found on the Pacific coast of the United States and Canada in the late 1800's introduced in shipments of imported Crassostrea virginica. The Atlantic oyster drill was introduced to the United Kingdom in shipments of C. virginica at the turn of the century. In this region, it has been reported from Essex and Kent in southeast Britain (Faasse and Ligthart 2007). Tributyltin (TBT) has been an effective control in the southeast Britain populations causing imposex in the females, a maculizing syndrome inhibiting reproductive processes (Gibbs et al. 1991). More recently following the ban of TNT in 1993, U. cinerea was reported from the Netherlands. It is suspected that U. cinerea may have been introduced in seed mussels imported from Sussex and Kent.
Urosalpinx cinerea poses a major concern because it usually thrives in its new habitat without specialized predators and parasites (Faasse and Ligthart 2007).
Damage to the oyster bed fisheries around the world has been estimated to be in the millions of dollars per year (Manzi 1970).
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Franz DR 1971. Population age structure, growth and longevity of the marine gastropod Urosalpinx cinerea Say. Biological Bulletin 140:63-72.
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Zachary A and DS Haven. 2004. Survival and activity of the oyster drill Urosalpinx cinerea under conditions of fluctuating salinity. Marine Biology 22:45-52.