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| shelled snails text index | photo index |
| Phylum Mollusca > Class Gastropoda |
| Moon
snails Family Naticidae updated Aug 10
Where seen? These fierce burrowing snails are commonly seen on our sandy shores. These snails are more commonly seen above ground at night. But a keen observer may still detect their presence by the distinctive trails these snails leave on the surface as they quietly burrow just beneath the sand. What are moon snails? Moon snails belong to the Family Naticidae. These include the Genus Natica, which have a thicker operculum that is shell-like (usually white); and the Genus Polinices, which have a thin operculum made of a horn-like material (usually yellowish) with several whorls. Features: About 2cm. When a moon snail is fully extended out of its shell, it has an amazingly large body compared to its shell. It achieves this by inflating its tissues with seawater. The body forms a wedge shape that helps the snail move under the sand. The front of the foot is used like a plough. A part of the foot covers the head as a protective shield. The tentacles and siphon stick out of this shield. The mantle (a part of its body) extends in two flaps over the shell on either side. A moon snail's shell often remains shiny and lustrous because the mantle envelopes its shell, and the snail spends most of its time under the sand. Encrusting animals have little chance of establishing on the shell of a living Moon snail. Sometimes mistaken for a sea slug when the mantle covers the shell. Here's more on how to tell apart animals that resemble sea slugs. What do they eat? Moon snails are fierce predators. They feed on bivalves and snails. A moon snail wraps its huge foot around the hapless prey to suffocate it. If this fails, it has a gland at the tip of its proboscis that secretes an acid to soften the victim's shell. With its radula, a hole is slowly drilled through the shell. The hole created by a moon snail is usually neat and bevelled. Moon babies: The sand collar is the moon snail's egg mass. 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 gives an indication of the size of the mother snail. 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. Sand collars are sometimes numerous on the sand bar and seagrass lagoon. More photos of sand collars we have seen. Role in the habitat: When a moon snail dies, its shell is quickly taken over by a hermit crab. Many of the moon snail shells you see on the surface will probably be so occupied. Living moon snails are rarely seen above ground during the day. Human uses: Some larger moon snail species are sold as food in Asian markets. Status and threats: Like other creatures of the intertidal zone, the rest of they are affected by human activities such as reclamation and pollution. Trampling by careless visitors and over-collection can also have an impact on local populations. |
 The body can expand to be MUCH bigger than the shell Changi, Jun 06  Tiny button snails leaping away from a hunting moon snail. East Coast, Jun 06  Clam shell with hole neatly drilled, possibly by a moon snail? Changi, Oct 10  Sand collar: egg mass of a moon snail. more photos of sand collars Pulau Sekudu, Jul 03 |
Moon
snails usually hunt and rest under the sand. Look for
trails in the sand!
 Changi, Jul 11 |
 Bivalve escaping a moon snail! |
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 Using its long foot, the bivalve 'leaps' away to safety. |
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Moon snails on Singapore shores
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| Family
Naticidae recorded for Singapore from Tan Siong Kiat and Henrietta P. M. Woo, 2010 Preliminary Checklist of The Molluscs of Singapore +from our observation.
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Links
References
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The Nature Society (Singapore), Singapore. 343 pp.
. IKAN-Unterwasserachiv. 723pp.|
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