Scotch Bonnet (also known as the Banded Bonnet)
Phylum: Mollusca, Class: Gastropoda, Order: Littorinimorpha, Family: Cassidae, Genus: Semicassis, Species: Semicassis granulata · Cassidae (Helmet and Bonnet family) · Gastropod (snail/univalve), whole shell, inflated subglobose spiral shape
Species
Semicassis granulata
Shell Type
Gastropod (snail/univalve), whole shell, inflated subglobose spiral shape
Family
Cassidae (Helmet and Bonnet family)
Size
Approximately 3.5 inches in length, which is slightly above average for this species. Adults typically range from 2 to 4 inches.
Color & Pattern
Creamy-white base color with subtle, faint yellowish-brown spiral bands of rectangular spots. The surface appears somewhat sun-bleached, presenting a uniform pale off-white tone with delicate texture coloration.
Rarity
Common, frequently encountered by divers and occasionally washed up on beaches after storms.
Habitat
Found in shallow subtidal waters, offshore sandy bottoms, and near coral reef margins, typically at depths ranging from low tide to 150 feet. It is a marine species.
Geographic Range
Western Atlantic Ocean, ranging from North Carolina through the Gulf of Mexico, the Caribbean, and down to Brazil.
Description
An attractive, sturdy, and inflated bonnet shell featuring a finely textured exterior composed of numerous intersecting radial and spiral ribs creating a beaded or cancellated grid pattern. It has a short spire, a large rounded body whorl, and a slightly flaring outer lip that is gently thickened and toothed on the inner margin.
Key Features
Distinguished by its inflated, rounded body whorl, prominent cancellated grid-like sculpture of tiny beads formed by intersecting cords, and a thick, slightly reflected outer lip with weak denticles.
Collector Value
Moderately desirable for regional and family collections, though common specimens hold modest market value, usually ranging from $5 to $15 depending on exact size and color preservation.
Condition Notes
Good condition. The shell is structurally intact with no major fractures, though the original bright color patterns are faded due to sun-bleaching or age. Collectibility grade is Good.
Interesting Facts
Living Scotch Bonnet snails are active carnivores that specialize in preying upon sea urchins and sand dollars. They immobilize their prey using specialized secretions before feeding.
Ecological Role
Acts as an important marine predator helping to control populations of benthic echinoderms like sea urchins, maintaining balance in sandy bottom and seagrass ecosystems.
Similar Species
Semicassisayla (Yellow Bonnet) and other Cassidae species, which can be distinguished by differences in nodule arrangement, overall coloration, and geographic distribution.
Beach Finding Tips
Look along sandy beaches of the southeastern United States and the Gulf of Mexico after heavy offshore storms or strong seasonal winds.