Janthina exigua Lamarck, 1816.
Description: Shell lightweight, globose, aperture more than half shell length. Spire whorls and last whorl rounded. Whorls sculptured with strong, crisp, dense V-shaped growth lines following curves of outer lip; spiral groove or ridge at periphery of last whorl; a few weak spiral grooves on base. Outer lip (when unbroken) with deep sinus at periphery. Umbilicus closed or partly open. Colour purple, with diffuse pale violet band below suture.
Size: Up to 17 mm in length.
Distribution: Worldwide, in tropical and temperate seas; available Australian specimens are from temperate waters; northern NSW, around southern Australia to south-western WA, including Tasmania.
Habitat: Pelagic: found washed up on ocean beaches; uncommon in NSW.
Comparison: See J. umbilicata.
Synonymy: A synonym, Janthina capreolata Montrouzier, 1860, was used by Iredale & McMichael (1962) for this species.
Remarks: This is a pelagic species as described in the introduction to this family. It floats on the surface of the sea utilizing a float secreted by the foot. Egg capsules are attached to the float.
Figs. 1,2: North Curl Curl Beach, NSW (C.362634)
Copyright Des Beechey 2008