West Indian Top Shell, Cittarium pica
West Indian Top, Cittarium pica. Shell collected off the beach of Cozumel Island, Quintana Roo, March 2021. Size: 5.1 cm (2.0 inches) x 4.3 cm (1.7 inches) x 4.0 cm (1.6 inches). Photographs and identification courtesy of Marina Sutormina, Stockholm, Sweden.
West Indian Top, Cittarium pica. Underwater photograph taken in coastal waters off Cozumel Island, Quintana Roo, March 2021. Photograph and identification courtesy of Marina Sutormina, Stockholm, Sweden.
West Indian Top Shell, Cittarium pica Collected offshore Cancun, Yucatan, may 5, 1990. Diameter 5 cm (1.9 inches) Height 3.5 cm (1.3 inches). Collection, identification, and photo by Bob Hillis, Ivins UT.
Phylogeny: The West Indian Top Shell, Cittarium pica (Linnaeus, 1758) is a gastropod member of the Tegulidae Family of Top Shells. The Cittarium Genus is one of eight genera in the Tegulidae Family, and this is the only species in the Cittarium Genus. They are also known as the Magpie Shell and the Caribbean as the Bulago Shell and Wilk Shell.
Description: Indian Top Shells are thick, heavy snail shells, made up of six convex whorls. The shoulders are rounded. The body whorl is globose and marked by low spiral ridges, though in larger specimens the ridges are often not present. The spire is fairly low and moderately pointed. The aperture is round and the umbilicus is very pronounced. The parietal callus is glossy, with a node that projects towards the umbilicus. The exterior of the shell is gray, with heavy, wavy, darker gray or black, diagonal lines. The bottom of the shell has a spiral pattern of black blotches, on a whitish background. The interior is whitish and iridescent. Older specimens can be completely black, and are often eroded. West Indian Top Shells reach a maximum of 13.7 cm (5.3 inches) in height.
Habitat and Distribution: West Indian Top are found on rocks and other hard substrates, in areas protected from strong wave action. They are often found in close proximity to Littorinidae, Nerita and Tegula species. They live intertidally, and to depths of 7 m (23 feet). They are a tropical Western Atlantic species that are found in Mexican waters of the Atlantic Ocean along the south facing coastline of the Yucatán Peninsula, in Caribbean waters. Some sources extend this range to Mexico’s entire east coast, including Gulf of Mexico waters.
Ecology and Behavior: West Indian Top are nocturnal, herbivorous grazers, feeding on algae and detritus. In turn they are preyed upon by shorebirds, crabs, fish, gastropods, lobsters, octopuses and sea stars. They are gonochoric and reproduce sexually, through broadcast spawning, with external fertilization. The eggs are laid as a mass, in jelly-like ribbons. They have life spans of thirty years. West Indian Top Snails engage in a commensal relationship with the Rathbunae Pea Crab, Nepinnotheres rathbunae, with the crab living within the mantle. The Black-rib Limpet, Lottia leucopleura, the Ringed Wormsnail, Dendropoma corrodens, tube dwelling polychaetes, and several species of algae are epibionts on West Indian Top Shells. Where the Land Hermit Crab, Coenobita clypeatus, exists, they frequently use the shells of West Indian Top Shells for housing and are dependent on healthy top shell population numbers.
Conservation: The West Indian Top has not been formally evaluated from a conservation perspective. However, while they are fairly common in some areas and have a relatively wide distribution, they are clearly vulnerable, and should be consider to be a species of Concern. This species is collected as a food source and as a decorative item. They are the third most economically important species in the Caribbean, after spiny lobsters and Queen Conch. Over-collecting of this species has led to them being extirpated in some regions. Efforts to repopulate this species over the past 100 years have met with limited success.
Synonyms: Livona pica, Trochus (Livona) picoides, Trochus picoides, and Turbo pica.