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Central and South Florida Gastropod Seashell Identification Guide: Moon Snails and Purple Sea Snails

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

Moon Snails

(Family) Naticidae

Distinguishing Characteristics: The Moon Snails have oval, almost perfectly spherical shells with a D-shaped aperture.  They have a reduced spire.  They have a hollow area within the columella called the umbilicus; this umbilicus is visible and open.  They lack a siphonal canal.

Habitat:  These snails live mostly burrowed in sand in shallow waters.

Diet:  Members of this family are very active carnivores that feed exclusively on buried bivalves.

Interesting Facts:  Also called Necklace Shells.

Scientific Name:  Neverita duplicata

Common Name:  Atlantic Moon Snail

Distinguishing Characteristics:  Large, grey shell with darker or lighter streaking.  Shell usually wider than high.  Umbilicus deep, but often covered by brown shell growth.  Maximum size 2 inches.

Interesting Facts:  Also called a Shark Eye.

Scientific Name:  Polinices lacteus

Common Name:  Milk Moon Snail

Distinguishing Characteristics: Solid, shiny and smooth white shell, which gives the species its common name.  Aperture and umbilicus surrounded by a thickened shell layer.  Maximum size around 1.5 inches.

Neverita duplicata

Atlantic Moon Snail

Polinices lacteus

Milk Moon Snail

Janthina janthina

Common Janthina

Purple Sea Snails

(Family) Janthinidae

Distinguishing Characteristics: The Purple Sea Snails have thin, fragile white and purple shells.  The shell is wider than it is tall, and has no siphonal canal.  The different species are difficult to tell apart.

Habitat:  These snails float on the ocean surface by attaching themselves to rafts of bubbles.

Diet:  This family primarily feeds upon surface-floating jellyfish such as the Portuguese Man o' War.

Interesting Facts:  Also known as the Purple Storm Snails or the Violet Snails.

Scientific Name:  Janthina janthina

Common Name:  Common Janthina

Distinguishing Characteristics:  Shell a striking purple on the underside, with a paler violet or white top.  Shell is much wider than it is tall.  Aperture very large, almost half the width of the shell.  Maximum size around 1.5 inches wide.