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
the left of the banded tentacles.
Siphon and tentcles
moon snails on Singapore shores
- 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.