Purple Sea Snail, Violet Snail
Phylum: Mollusca, Class: Gastropoda, Order: Littorinimorpha, Family: Epitoniidae, Genus: Janthina, Species: Janthina janthina · Epitoniidae (Wentletrap family) / formerly Janthinidae · Gastropod, whole shell, spiral shape
Species
Janthina janthina
Shell Type
Gastropod, whole shell, spiral shape
Family
Epitoniidae (Wentletrap family) / formerly Janthinidae
Size
Approximately 15 to 20 mm in diameter, which is average for this species. Adult shells typically range from 15 to 38 mm.
Color & Pattern
Striking bicolored pattern with a deep violet-purple base fading to a lighter, translucent lavender or whitish shade near the apex. The colors are entirely natural and create a countershading effect.
Rarity
Uncommon to Rare as a whole, intact beach find, because the fragile shells frequently break before washing ashore.
Habitat
Pelagic (open ocean), drifting at the surface of warm and temperate seas using a self-made bubble raft.
Geographic Range
Cosmopolitan in tropical and warm temperate oceans worldwide, including the Atlantic, Pacific, and Indian Oceans, as well as the Mediterranean Sea.
Description
A delicate, fragile, globose to conical univalve shell with a low spire and a wide, angled body whorl. The surface is smooth with fine growth lines, featuring a sharp outer lip and an open aperture. The countershaded purple coloration serves as camouflage in the open pelagic environment.
Key Features
Thin, fragile translucent shell structure, deep violet-purple coloration, low spire, globose body whorl, and complete lack of an operculum in adults.
Collector Value
Moderately high desirability among specialized marine shell collectors due to its pelagic lifestyle and fragile nature, making pristine whole specimens prized additions.
Condition Notes
The specimen appears to be in remarkably good, intact condition with its delicate structure preserved and vibrant natural purple pigmentation retained. Collectibility grade is Fine to Good.
Interesting Facts
Janthina janthina is a pelagic gastropod that never touches the sea floor. It builds a raft of mucus-coated air bubbles to stay afloat upside down at the surface, where it actively hunts and feeds on by-the-wind-sailors (Velella) and Portuguese man o' wars.
Ecological Role
Acts as a specialized surface predator controlling populations of pelagic cnidarians. It serves as prey for seabirds and pelagic fish, though its purple coloration provides camouflage against predators looking both up and down.
Similar Species
Other species within the genus Janthina, such as Janthina exigua and Janthina pallida, which can be distinguished by smaller sizes, differing spire heights, and variations in the shade of purple.
Beach Finding Tips
Best found on ocean-facing sandy beaches following strong onshore winds and storms that drive pelagic organisms and floating debris toward the coastline.