Species Description: The true tulip snail, Fasciolaria tulipa, is one of the larger subtidal gastropods found in the Indian River Lagoon (IRL). It belongs to the family Fasciolariidae, which is characterized by: large, elongate, spindle-shaped shells with elevated spires, or points; columellar folds in the shell on the left side of the aperture; long, well-developed siphonal canals at the base of the shell; and thick, horny opercula (Leal 2002).
The true tulip is a dextral snail, meaning that the aperture (opening) of the shell is located on the right side when viewing the organism from underneath with the spire pointed upward. Approximately 9 convex whorls make up the whole of the shell, which is smooth except for fine growth lines (e.g. Leal 2002). The background color of the shell varies among individuals from cream to brown to reddish orange, often overlaid with irregular blotches. Numerous interrupted black spiral lines appear across the shell surface, ranging from 25 to 39 in adult snails (Wells 1969). The lines extend onto the lip of the shell, giving it a notched appearance. In living snails, the body is bright orange to red, including the muscular foot that extends out of the shell when the snail is active. The thick operculum is attached to the end of the foot, is brown to black in color, and bears visible concentric growth rings (e.g. Wells 1969).
Potentially Misidentified Species: The true tulip is often confused with its close relative, the banded tulip, Fasciolaria hunteria. The ranges and preferred habitats of these two species can overlap, and juveniles may be difficult to distinguish from one another. As they grow larger, the identifying characteristics of each species become more evident. Unlike the true tulip, the shell color of the banded tulip is usually grayish and is overlaid with 4-8 distinct and unbroken black spiral lines (e.g. Wells 1969). Also distinguishing it from F. tulipa is the color of the foot, which is black with white spots; and the smaller size of the shell in fully grown adults, which only reaches about 8 to 10 cm (Kaplan 1988; Ruppert & Fox 1988).
Regional Occurrence: The range of F. tulipa extends on the Atlantic coast of the United States from North Carolina to Florida, throughout the Gulf of Mexico from Florida to Texas, and south through the Caribbean to Brazil (Kaplan 1988; Abbott & Morris 1995; Leal 2002). Most populations are found subtidally in warm, shallow estuarine or coastal marine environments such as seagrass beds, sand flats and coral reefs (e.g. Humfrey 1975; Andrews 1994).
IRL Distribution: The tulip snail can be found throughout the IRL in seagrass beds and on tidal flats. They are active in shallow water during high tide and often burrow under the sediments when exposed during low tide.
Age, Size, Lifespan: The true tulip is a large snail, surpassing the length of its relative, F. hunteria, as an adult. Total shell lengths have been documented to equal or exceed 20 cm (e.g. Kaplan 1988; Leal 2002), although the average length of surveyed adult specimens is approximately 13 cm (Wells 1969). The width of the shell is about one half the length, and the length and width of the operculum in adult snails averages approximately 62 cm and 28 cm, respectively (Wells 1969). In terms of size, some sexual dimorphism has been observed for F. tulipa, with the average length of females surpassing that of males (Wells 1969).
As with most marine invertebrates, little is known about the lifespan or maximum age of wild populations, which varies substantially with food availability, predator abundance and environmental conditions.
Abundance: Information regarding the abundance of F. tulipa is scarce, and populations in the IRL are poorly documented. However, studies conducted by Wells in 1969 on snails within Alligator Harbor off the northwest coast of Florida found densities of one individual per 917 m-2.
Although quite low, these measurements were taken at the start of the breeding season in March and it was estimated that densities likely reached as many as 3-4 times this amount in the summer months.
Reproduction: Aside from the probable smaller shell size when compared to females, male F. tulipa can be identified by the presence of a penis located on the right side of the body directly behind the head (Wells 1969). As with other snails of its family, the tulip snail reproduces sexually via copulation. During mating, the female remains in the usual upright position on the sand while the male flips over, aligning the apertures of both shells before inserting the penis into the female. Once joined, snail pairs have been known to remain attached for up to 2 hours, usually undisturbed by tidal cycles or during relocation to laboratory aquaria (Wells 1969). Mating may occur several times in one season, and some individuals have been observed to mate up to 3 times in a single week. In warm waters, F. tulipa reproduces year-round. Although peak spawning times for populations in the IRL are not documented, studies on snails in Campeche Bay, Mexico have found that spawning peaks from October to December (Aranda et al.2003).
Embryology: Most marine invertebrates have planktonic developmental stages that appear quite different in form from the adults. Parental involvement in the reproductive process culminates in the releasing of either eggs and sperm or larvae into the water column. From there, minute larvae grow and metamorphose into juveniles. However, a few species like the tulip snail are known as direct developers. Instead of developing as plankton, the offspring of these species are contained in eggs or eggs cases, often attached to a hard surface during development, before finally emerging as miniature versions of the adult.
Following a successful mating event, females will produce clusters of egg capsules comprised of a flexible but rugged translucent protein (Ruppert & Fox 1988). Each capsule is approximately 1.8 cm long and shaped like a laterally flattened cone. The cluster is attached to a hard surface such as a vacant shell or rock. Only a small portion of the 600-800 eggs laid in a cluster develop normally, and the remainder are fed upon by the healthy larvae (Burger & Thornton 1935; Miloslavich 1996). Once the snails are fully developed, the hatchlings crawl from holes formed in the tops of the capsules. These egg capsules and those of similar species often become dislodged from the benthos and wash up on nearby beaches, usually after they have hatched.
Temperature & Salinity: Little information is available concerning the physical tolerances of F. tulipa. However, its natural range encompasses marine and estuarine habitats in tropical and subtropical climate zones. This pattern of distribution suggests that tulip snail populations prefer and/or require warm, saline waters in order to thrive.
Predators & Escape Responses: Aside from being cannibalized, F. tulipa is also preyed on by the horse conch, Pleuroploca gigantea, sting rays, and crabs of the genus Calappa (Wells 1969). Although little information is available concerning other predators of F. tulipa, it is likely that both juvenile and adult tulip snails are consumed by a variety of other carnivorous snails, crabs and other crustaceans, sea stars, and bony fishes.
Like many other snails, the tulip snail reacts to threats by retracting its body into the shell and using its hard operculum to completely seal the aperture, protecting the soft tissue from predators and other environmental dangers. In addition, snails often retreat away from potential hazards or thrash their muscular foot to escape a predators grasp (Wells 1969).
Economic Importance: Although tulip snails are not commonly found in seafood markets or restaurants, small and localized recreational fisheries exists for the species (Leal 2002). In addition, cleaned shells and opercula of F. tulipa are commonly found for purchase in shell shops and online.
Abbott, RT & PA Morris. 1995. A Field Guide to Shells: Atlantic and Gulf coasts and the West Indies. Houghton Mifflin. Boston, MA. USA. 512 pp.
Andrews, J. 1994. A Field Guide to Shells of the Florida Coast. Gulf Publishing. Houston, TX. USA. 182 pp.
Aranda, DA, Cárdenas, EB, Morales, IM, Zárate, AZ & T Brulé. 2003. A review of the reproductive patterns of gastropod mollusks from Mexico. Bull. Mar. Sci. 73: 629-641.
Burger, JW & CS Thornton. 1935. A correlation between the food eggs of Fasciolaria tulipa and the apyrene spermatozoa of prosobranch mollusks. Biol. Bull. 68: 253-257.
Humfrey, M. 1975. Sea Shells of the West Indies: A guide to the marine molluscs of the Caribbean. Taplinger Publishing. New York, NY. USA. 351 pp.
Kaplan, EH. A Field Guide to Southeastern and Caribbean Seashores: Cape Hatteras to the Gulf Coast, Florida, and the Caribbean. Houghton Mifflin. Boston, MA. USA. 1988.
Leal, JH. 2002. Fasciolariidae. pp. 117-118. In: Carpenter, KE (Ed.), The living resources of the Western Central Atlantic. Volume 1: Introduction, molluscs, crustaceans, hagfishes, sharks, batoid fishes and chimaeras. FAO species identification guide for fishery purposes and American Society of Ichthyologists and Herpetologists special publication no. 5. FAO, Rome. pp. 1-600.
Miloslavich, P. 1996. Biochemical composition of prosobranch egg capsules. J. Moll. Stud. 62: 133-135.
Ruppert, EE & RS Fox. 1988. Seashore Animals of the Southeast: A guide to common shallow-water invertebrates of the southeastern Atlantic coast. Univ. South Carolina Press. Columbia, SC. 429 pp.
Wells Jr., FE. 1969. An ecological study of two sympatric species of Fasciolaria (Mollusca: Gastropoda) in Alligator Harbor, Florida. Veliger 13: 95-108.