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Phylum Mollusca > Class Gastropoda > Family Neritidae
Dubious nerite snail
Clithon oualaniensis
Family Neritidae
updated Jul 2020

Where seen? This tiny snail is sometimes seen in large numbers on sandy shores near monsoon drains and other sources of freshwater on some of our shores, sometimes among seagrasses and seaweeds. It seems to prefer the upper reaches of monsoon drains leading to the sea or slow-moving, sheltered, shallow waters. Also seen in silty lagoons. The study by Tan & Clements (2008) found this snail on sandy banks of mangrove streams, on sand in drains and canals, intertidal muddy sand banks, and on mud in mangroves. Sites included: Sarimbun, Punggol, Pulau Ubin, Pasir Ris, Sungei Changi, Changi, Tanah Merah, Sungei Bedok, Marina East, Kallang and Tuas.

Features: 0.3-0.5cm. Shell thin spherical with a large semi-circular shell opening. Shell smooth glossy. Shell pattern yellow or olive background with delicate black lines in various designs; from simple lines to more complex patterns. It is said no two shells are identical. Operculum thin smooth horn-like material usually greyish. Body pale with fine black stripes, and long slender tentacles.

Tuas, Nov 06

East Coast, Nov 08

Thin greyish operculum.
Tanah Merah, May 09

Striped body with long tentacles.
Tanah Merah, Oct 10

Striped body with long tentacles.
Tanah Merah, Dec 11
Dubious babies: The Dubious nerite lays white circular egg capsules that are miniature versions of other Nerite egg capsules. Each egg capsule contains many eggs. These hatch into free-swimming larvae that only later settle down to develop into snails.

Egg cases laid on seagrass.
East Coast, Dec 08

Egg cases laid on seagrass.
Tanah Merah, Oct 10

Egg cases laid on one another!
Sentosa, Apr 09
What does it eat? This tiny snail grazes on algae.

Status and threats: This beautiful snail is listed as 'Vulnerable' on the Red List of threatened animals of Singapore. According to the Singapore Red Data Book: "Populations along the original shores have been wiped out by reclamation."

Dubious nerite snails on Singapore shores
On wildsingapore flickr

Other sightings on Singapore shores

East Coast-Marina East, Jul 20

Photo shared by Vincent Choo on facebook.

Lazarus, Dec 08
Photo shared by Loh Kok Sheng on his blog.

Seringat-Kias, Nov 20

Photo shared by Marcus Ng on facebook.

Pulau Sudong, Dec 09

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, S.K. & Clements, R. (2008) Taxonomy and distribution of the Neritidae (Mollusca: Gastropoda) on Singapore. Zoological Studies 47(4): 481-494.
  • Tan, K. S. & L. M. Chou, 2000. A Guide to the Common Seashells of Singapore. Singapore Science Centre. 160 pp.
  • Davison, G.W. H. and P. K. L. Ng and Ho Hua Chew, 2008. The Singapore Red Data Book: Threatened plants and animals of Singapore. Nature Society (Singapore). 285 pp.
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