Mollusca
Pleuroploca gigantea
(Florida Horse Conch)
Size
Length: reaching 48cm ( 19")
Recognition Characters
Spindle-shaped, large with an elongate conical spire. Spire whorls angled by 8-10 strong axial ribs that form triangular knobs. Columella has 2 strong spiral ridges near base. Aperture is oval. Canal is long, open, and slightly twisted. Operculum is thick, horny, oval, and pointed at 1 end.
Color
Exterior whitish-yellow, orange, or brown.
Habitat & Depth
On sand and rubble. Shallow intertidal to 20m.
Distribution at GRNMS
Rare on reef. May be more common on sandy and muddy substrates around reef.
Geographic Range
North Carolina south to the Florida Keys, Gulf of Mexico
Behavior & Notes
This species is not common at GRNMS but may occasionally visit to lay egg masses on reef. Egg capsules have been observed by divers. This is the largest gastropod in the U.S. range and one of the largest in the world. It preys primarily on other smaller gastropods such as the Tulip Shell, Lightning Whelk, and Lace Murex, and the bivalve pen shells. The egg masses are found on sand and consist of clusters of flattened, vase-shaped capsules that have horizontal ridges on the outside.
Synonyms
Rehder 1981