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 |  José H. Leal

Shell of the Week: The Scotch Bonnet, Redux

When checking past segments of the “Shell of the Week”, I realized that it has been a long time since we chatted about the unforgettable Scotch Bonnet (Semicassis granulata)! Normally reaching around 40–55 mm (approximately 1.6–2.2 inches), but with a maximum recorded length of 121 mm (4.76 inches), Scotch Bonnets are easily recognizable by their egg-shaped shells with engraved net-like lines and a regular pattern of squarish orange, or brown spots.

Semicassis granulata. From off Cartagena, Colombia. Illustration: Patricia A. Starkey.   

The early growth of Scotch Bonnets includes pelagic (open-water) larval stages, which can be passively carried by ocean currents. Adults feed on echinoderms such as sand dollars, sea biscuits, and sea urchins, by drilling into their tests (“shells”) using a sulfuric acid secretion. The species lives offshore from North Carolina to Brazil, including the Gulf of Mexico. And it is the State Shell of North Carolina! 

Semicassis granulata. From Lower Matecumbe Key, Florida Keys. Illustration: Patricia A. Starkey.  

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