Mollusca
Janthina janthina
(Common Janthina)
Size
Height: To 2.5cm (1")
Recognition Characters
Shell is round, smooth, and thin with a low spire. Body whorl is large and slightly angled at periphery.
Color
Whitish purple with deep purple base.
Habitat & Depth
Float on surface of ocean.
Distribution at GRNMS
Rare at GRNMS. Empty shells may occasionally be encountered while diving.
Geographic Range
Atlantic Coast, Caribbean
Behavior & Notes
Janthina animals are specialized for life at the surface of the open ocean. The snails are heavier than water and construct a raft of air bubbles entrapped in mucus to keep themselves afloat. They feed on floating cnidarians such as Physalia (Portuguese man-o-war) or Velella (by-the-wind-sailor). They are often found on the beach washed up after storms. They are a tropical snail but are carried northward by the Gulf Stream.
Synonyms
Abbott 2001, Rehder 1981