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Phylum Mollusca > Class Gastropoda
Moon snails
Family Naticidae
updated Sep 12
if you learn only 3 things about them ...
Moon snails usually hunt and rest under the sand. Look for trails in the sand!
They are fierce predators that hunt other snails and clams.
The body of a moon snail can inflate to many times the size of its shell.

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. The Naked moon snails of the Genus Sinum have thin shells and very large bodies.

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


Mating?


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

Changi, Jul 11

Bivalve escaping a moon snail!


Using its long foot, the bivalve 'leaps' away to safety.

Moon snail attempting to eat a bivalve as big as itself!
Filmed on Cyrene Reef Aug 2013

shared by Heng Pei Yan on her blog.

Moon snails on Singapore shores




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.
^from WORMS

  Family Naticidae
  Eunaticina coarctata
Eunaticina linneana
Eunaticina papilla

^Mammilla sebae=Polinices sebae

Natica alapapilionis=^Naticarius alapapilionis
Natica arachnoidea

Natica gualteriana
(Spotted moon snail)
Natica marochiensis
Natica vitellus (Calf moon snail)

^Naticarius onca=Natica onca
(China moon snail)
^Naticarius zonalis=Natica zonalis (Pink moon snail)

^Notocochlis tigrina=Natica tigrina (Tiger moon snail)=Natica maculosa

^Neverita didyma=Polinices didyma (Ball moon snail)

Polinices albumen (Egg-white moon snail)
Polinices mammilla (Oval moon snail)
Polinices mammatus
Polinices melanostomoides
Polinices melanostomus
Polinices peselephanti
(Elephant Foot's moon snail)
Polinices powisianus

Sigatica pomatiella


Sinum sp. (Naked moon snail)
Sinum delessertii
Sinum eximium
Sinum haliotoideum
Sinum incisum
Sinum neritoideum

+^Tanea areolata=Natica areolata
(Zebra moon snail)
^Tanea euzona=Natica euzona

^Tanea lineata=Natica lineata
(Lined moon snail)
^Tanea undulata=Natica undulata

Links

References

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