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Phylum Mollusca > Class Gastropoda > Family Naticidae
Ball moon snail
Neverita didyma
Family Naticidae
updated Oct 2016

Where seen? This pearly white moon snail is commonly seen on our sandy Northern shores. Especially at night or on a cool day, usually busy ploughing through the sand in search of prey, near seagrass areas. Elsewhere, it is found in sandy to muddy bottoms. It was previously known as Polinices didyma.

Features: 3-5cm. Shell thick, spherical, the spiral tip not sticking out so that the overall shape resembles a ball (Didyma means 'testicles'). Shell smooth usually plain white sometimes with pearly pastel shades, with narrow white spiral at the spire, sometimes with irregular blotches of darker colours.On the underside near the shell opening there is a brown blotch and a small depression. Operculum made of a thin horn-like material, smooth and yellow. Body plain white with more opaque white bands on the tentacles.

Sometimes mistaken for the Oval moon snail (Polinices mammilla) that is easily distinguished by its oval shell which on the underside is completely white (no brown patch) and has a bump instead of a depression.

What does it eat? This snail is often seen actively hunting button snails (Umbonium vestiarum).

Human uses: It is collected as food and for the shell trade. In Thailand it is commonly collected using fishing nets at depths of 2-10m.

Body much larger than its shell.
Changi, Jun 05


Siphon the left of the banded tentacles.

Changi East, Oct 11

Tanah Merah, Feb 07

Changi, May 11

Siphon and tentcles

Ball moon snails on Singapore shores

Photos of Ball moon snails for free download from wildsingapore flickr

Distribution in Singapore on this wildsingapore flickr map

Links

References

  • Tan Siong Kiat and Henrietta P. M. Woo, 2010 Preliminary Checklist of The Molluscs of Singapore (pdf), Raffles Museum of Biodiversity Research, National University of Singapore.
  • Tan, K. S. & L. M. Chou, 2000. A Guide to the Common Seashells of Singapore. Singapore Science Centre. 160 pp.
  • Abbott, R. Tucker, 1991. Seashells of South East Asia. Graham Brash, Singapore. 145 pp.
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