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Central and South Florida Gastropod Seashell Identification Guide: Helmets

This guide should serve to teach the public how to identify local Central and South Florida gastropod seashells.

Helmets

(Family) Cassidae

Distinguishing Characteristics: The Helmet and Bonnet snails have large, thick body whorls which often have "teeth" on the inner lip of the aperture.  They also have a "parietal shield"- the very flat, smooth area next to the inner lip of the aperture.  This helps them glide over and burrow into sand.

Habitat:  These snails prefer to live on sandy bottoms in water up to 330 feet.  They burrow under the sand during the day and hunt at night.

Diet:  All members of this family hunt echinoderms such as sea urchins.

Interesting Facts:  The larger helmets have large, heavy shells that can be carved into beautiful works of art called cameos.  Read more about cameos here.

Scientific Name:  Cassis madagascariensis

Common Name:  Emperor Helmet

Distinguishing Characteristics:  Large, heavy shell with rounded knobs on the whorls.  The parietal shield is rounded.  Brown or black markings between the teeth of the aperture.  Maximum size 16 inches.

Interesting Facts:  The species was accidentally thought to come from Madagascar, leading to the odd scientific name.

Scientific Name:  Cassis tuberosa

Common Name:  King Helmet

Distinguishing Characteristics:  The parietal shield is triangular.  There is black coloration between the teeth of the aperture and between 7-8 dark stripes on the outer lip of the shell.  Maximum size 14 inches.

Scientific Name:  Cassis flammea

Common Name:  Flame Helmet

Distinguishing Characteristics:  The parietal shield is oval or rounded.  This species has no brown or black markings between the teeth of the aperture.  The wavy pattern on the shell gives the species its common name.  Maximum size 5 inches.

Scientific Name:  Semicassis granulata

Common Name:  Scotch Bonnet

Distinguishing Characteristics:  The shell is pale yellow to white, checkered with pale brown spots that resemble plaid, giving the species its common name.  The body whorl is large and inflated, somewhat resembling an egg.  Maximum size 3.5 inches.

Interesting Facts:  This species is the official shell of North Carolina, adopted in 1965.  Read more about it here.

Cassis madagascariensis

Emperor Helmet

Cassis tuberosa

King Helmet

Cassis flammea

Flame Helmet

Semicassis granulata

Scotch Bonnet