Scotch bonnet (sea snail)
The Scotch bonnet (Semicassis granulata) is a medium-sized to large species of sea snail, a marine gastropod mollusk in the subfamily Cassinae, the helmet shells and bonnet shells. The common name "Scotch bonnet" alludes to the general outline and color pattern of the shell, which vaguely resemble a tam o' shanter, a traditional Scottish bonnet or cap. The shell is egg-shaped and fairly large, 2 to 4 inches (5 to 10 cm) in maximum dimension, with a regular pattern of yellow, orange or brown squarish spots. The surface sculpture of the shell is highly variable: the surface can be smooth and polished, have grooves, be granulated, or even be nodulose on the shoulder of the whorls.
This species lives intertidally and subtidally on sandy substrates, and is found primarily in the tropical and subtropical Western Atlantic Ocean, from North Carolina to Uruguay. It is the most common species in this subfamily in North America. A similar-appearing sea snail in the Mediterranean Sea and Northern Atlantic Ocean, Semicassis undulata, is currently considered to be a separate species. The exact taxonomy of Semicassis granulata has been unclear in the past: as well as the current combination, 38 other combinations and synonyms exist.
In the spring, the adult females of this species lay eggs in tower-shaped structures. The eggs hatch as veliger larvae, which can float in the plankton for up to 14 weeks before settling onto the seabed as tiny snails. Crabs are a predator of this sea snail. After the death of the snails, if the shells are still intact they are often used by hermit crabs.
In 1965, in the US, the Scotch bonnet shell was named as a state symbol of North Carolina, the first designation of a US state shell.
Distribution[edit]
There are published records of the nominate subspecies Semicassis granulata granulata from several warm-water and tropical areas of the Western Atlantic Ocean.[12] It is considered the most common species of Cassinae in North America.[30] Regions and countries where this species occurs include the East Coast of the US, in North Carolina, South Carolina, Georgia and Florida (East Florida, West Florida, and the Florida Keys). It has also been recorded on the Gulf Coast of the US, including Louisiana and Texas. The species is known to occur in the Caribbean Coast of Central America, including Mexico (Quintana Roo), Nicaragua, Costa Rica, Panama and Colombia, as well as Venezuela (Gulf of Venezuela, Carabobo, Sucre, Isla Margarita and Los Testigos Islands). It is also found in Bermuda, the Greater Antilles, Cuba, Jamaica and Puerto Rico, and further south in the Atlantic coast of South America, Suriname, Brazil (Amapá, Maranhão, Ceará, Rio Grande do Norte, Pernambuco, Alagoas, Bahia, Espírito Santo, Rio de Janeiro, São Paulo, Paraná and Santa Catarina), and also in Uruguay. As of 2009, this species had apparently not been reported in the literature as occurring in the Lesser Antilles.[12]
In contrast, the species Semicassis undulata occurs in the Mediterranean Sea, and parts of the North Atlantic Ocean, including Portugal and the Azores.[31]
Human use[edit]
In 1965, the US state of North Carolina named the Scotch bonnet as its official state shell, in honor of the abundance of Scottish settlers that founded the state.[37][40] With this designation, North Carolina became the first state in the US to have a state shell.[37]
Populations of S. granulata have been suffering a decline due to increased collection and accidental harvesting by commercial fishermen.[16]
Media related to Semicassis granulata at Wikimedia Commons