shelled snails text index | photo index
Phylum Mollusca > Class Gastropoda
Planaxis snail
Planaxis sulcatus
Family Planaxidae
updated Sep 2020
Where seen? This large 'groovy' snail is commonly seen, usually in clustered together in large numbers, on rocky shores and seawalls on our Southern shores. Elsewhere, it is called clusterwink for this grouping habit. It is not active at low tide but disperses to feed at high tide.

Features: 2-2.5cm. Shell thick with strong squarish spiralling cords (Sulcus means 'grooved'). Colour blackish to cream sometimes with white or yellowish spots. Shell opening wide, inner surface white sometimes with dark purple grooves. Operculum thin, horn-like material and dark coloured. Body pale, small foot with a pale underside dark mottled pattern above, long tentacles with dark bands.

Sometimes confused with Periwinkle snails which are found in similar habitats. But Periwinkles are much smaller, have thinner shells and don't have strong spiralling cords like the Planaxis snail.

Sisters Islands, Feb 06

Pulau Semakau, May 08

Pulau Jong, Jul 12
Baby planaxis: The female broods her young. Fertilisation is internal and the mother snail has a special brood pouch in the foot where the embryos are reared before they are released into the water as free-swimming larvae.

What does it eat? It grazes on microalgae growing on the rocks.

Status and threats: Planaxis snails are not listed among the threatened animals of Singapore. However, like other creatures of the intertidal zone, they are affected by human activities such as reclamation and pollution. Trampling by careless visitors can also have an impact on local populations.

Planaxis snails on Singapore shores
On wildsingapore flickr

Other sightings on Singapore shores

Pulau Jong, Nov 08

Photo shared by Chim Chee Kong on his flickr.

Family Planaxidae recorded for Singapore
from Tan Siong Kiat and Henrietta P. M. Woo, 2010 Preliminary Checklist of The Molluscs of Singapore.

  Family Planaxidae
  Couthouyia styliferinus

Fissilabia decollata

Planaxis sulcatus
(Planaxis snail)



  • Tan SK & Low MEY (2014) Singapore Mollusca: 5. The subfamily Planaxinae (Gastropoda: Caenogastropoda: Cerithioidea: Planaxidae). Nature in Singapore, 7: 15–23.
  • 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.
  • Wee Y.C. and Peter K. L. Ng. 1994. A First Look at Biodiversity in Singapore. National Council on the Environment. 163pp.
  • Ng, P. K. L. & Y. C. Wee, 1994. The Singapore Red Data Book: Threatened Plants and Animals of Singapore. The Nature Society (Singapore), Singapore. 343 pp.
  • Abbott, R. Tucker, 1991. Seashells of South East Asia. Graham Brash, Singapore. 145 pp.
links | references | about | email Ria
Spot errors? Have a question? Want to share your sightings? email Ria I'll be glad to hear from you!
wildfactsheets website©ria tan 2008