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Phylum Mollusca > Class Gastropoda
Top shell snails
Family Trochidae
updated Sep 2020
Where seen? These snails with top-shaped shells are commonly seen on many of our rocky shores including man-made sea walls. Top shell snails are not as well adapted to dry conditions as the Nerites and Periwinkles, and are thus generally found closer to the low water mark.

Features: 3-15cm. Shell thick. Some are shaped like a conical top, the spinning toy. The operculum is circular with concentric rings usually clearly visible. It is made of a thin, horn-like material and is flexible. This allows the snail to withdraw deep into the coils of the shell, hopefully out of the reach of crab pincers. The shell is sometimes covered in encrusting lifeforms. In some species, the body mantle of the living animal is fringed with long tentacles.

Sometimes confused with the Turban snail (Family Turbinidae) which has a shell with more distinct whorls and a thick, chalky operculum. While many Top snails have a more conical shell and a thin operculum made of a horn-like material. Here's more on how to tell apart turban and top shell snails.

The Spotted top shell snail has a large foot with tentacles fringing the body mantle.
Labrador, May 05

The Toothed top shell snail also has a large foot with tentacles fringing the body mantle.
St. John's Island, Aug 05

Tiny button snails have a long mobile foot and tentacles fringing the body mantle.
East Coast, Aug 12
What do they eat? Top shells graze the algae that thrive on the rocks, scraping this off with their radula.

Human uses:
The shell is lined with mother-of-pearl. Larger species are collected for food and their shells that are made into ornaments and pearl buttons. This is still a significant industry in some Pacific Islands and effort is being made to establish a susbtainable method of farming these snails.

Status and threats: Button snails are listed as 'Vulnerable' on the Red List of threatened animals of Singapore.

Some Top shell snails on Singapore shores



Family Trochidae recorded for Singapore
from Tan Siong Kiat and Henrietta P. M. Woo, 2010 Preliminary Checklist of The Molluscs of Singapore.
in red are those listed among the threatened animals of Singapore from 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.
^from WORMS.
+Other additions (Singapore BIodiversity Records, etc)

  Top shells seen awaiting identification
Species are difficult to positively identify without close examination.
On this website, they are grouped by external features for convenience of display.

  Family Trochidae
  Chrysostoma paradoxum (Orange-mouth top shell snail)

Clanculus granosus=^Clanculus bronni
Clanculus margaritarius

Ethminolia vitiliginea

Monilea callifera
Monilea lentiginosa
Monilea solanderi

Monodonta labio
(Toothed top shell snail)

Pseudominolia musiva

+Stomatella impertusa

Thalotia zebuensis

Trochus maculatus
(Spotted top shell snail)
Trochus radiatus
Trochus tricatenatus

Umbonium vestiarium
(Button snail) (VU: Vulnerable)

  ^Family Solariellidae
  Minolia biangulosa
Minolia holdsworthana=^Pseudominolia musiva
Minolia singaporensis

Links

References

  • Toh Chay Hoon, Tan Siong Kiat & Martyn E. Y. Low. 10 January 2014. A record of Stomatella impertusa in Singapore. Singapore Biodiversity Records 2014: 19
  • 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.
  • 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.
  • Abbott, R. Tucker, 1991. Seashells of South East Asia. Graham Brash, Singapore. 145 pp.
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