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Phylum Mollusca > Class Gastropoda > Family Naticidae
Sand collars of moon snails
Family Naticidae
updated Aug 2020
if you learn only 3 things about them ...
Although it feels plasticky and dead, the sand collar is full of living baby snails!
The size of the collar depends on the size of the mother moon snail.
When the baby snails hatch, the sand collar disintegrates.

Where seen? These frilly edged flat spirals are sometimes numerous on sandy shores, as well as seagrass areas.

What is a sand collar?
The sand collar is the egg mass of a moon snail. A moon snail lays her eggs at night. The eggs are laid singly in capsules which are embedded in a matrix of sand grains - a combination of mucus and sand which forms a gelatinous sheet that hardens. She lies at the center of the collar as she creates it, so the hole in centre of the collar may give an indication of the size of the mother snail.

It's alive! Although the collar feels hard, plasticky and appears dead, each collar can contain thousands of living eggs. When the eggs hatch, the collar disintegrates. Thus, an intact collar has living snails in it! Please don't damage the sand collars.

Unique collars: Can we tell which kind of moon snail laid the sand collar? One study suggests that each species of moon snail lays a consistently distinctive sand collar. With differences in the overall shape and size, number of coils, capsule size and packing density in different species.

Pulau Sekudu, Jul 03

Chek Jawa, Nov 04

Pulau Sekudu, Jul 08

Sand collars on Singapore shores
On wildsingapore flickr

Links References
  • Dun-Ru Kang et al. Egg-collar morphology and identity of nine species of Naticidae (Gastropoda) in Taiwan, with an assessment of their phylogenetic relationships. November 2018. Journal of Molluscan Studies 84:354-378 DOI: 10.1093/mollus/eyy041
  • Tan, K. S. & L. M. Chou, 2000. A Guide to the Common Seashells of Singapore. Singapore Science Centre. 160 pp.
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