seen? This almost spherical moon snail is commonly seen on
a few of 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 smooth glossy, thick heavy,
spherical, the spiral tip not sticking out so that the overall shape
resembles a ball (Didyma means 'testicles'). Shell pattern 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, a brown blotch and a
small depression. Operculum smooth, made of a thin horn-like material, yellow. Body huge, plain white. Tentacles with more opaque white bands.
Sometimes mistaken for the Oval
moon snail that is easily distinguished
by its more tear-drop shaped shell which on the underside is completely white (no brown
patch) and has a bump instead of a depression. The Ball moon snail is less shy and doesn't immediately retract completely into its shell the way the Oval moon snail does.
Siphon (upper left) and tentcles
|What does it eat? This snail is
often seen actively hunting Button
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.
moon snails on Singapore shores
|Other sightings 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.