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Button
shells
Umbonium vestiarum
Family Trochidae |
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Button
shells litter the northern arm of the sand bar of Chek Jawa in the
hundreds. They usually lie buried just under the sand. They come in
an amazing variety of colours and patterns. It is said that no two
Button shells are alike! These shells are so enchanting that the guides
call them the 'Jewels of Chek Jawa'.
Button shells are hunted by Moon snails. To
get away from them and other disturbers, Button shells make a short,
spiralling leap then quickly bury themselves into the sand again.
On the northern arm of the sand bar, you might see the tiny trails
left by panicky Button shells, punctuated by little holes where they
disappeared into the sand. They have a long highly mobile, leaf-like
foot which is used to burrow into the sand. Their smooth, round shells
are streamlined for rapid burrowing into wet sand.
Button food: Unlike most other
gastropods and more like bivalves, Button shells filter feed for detritus
and plankton. Lying buried just beneath the sand, they stick out their
eyes and a tentacle above the sand to gather edible bits.
Role in the ecosystem: Button
shells are among the favourite prey of Moon snails. Other large animals
probably also snack on them. Empty buttons shells are favourite homes
of tiny hermit crabs. So please resist the temptation of taking even
an empty Button shell. A homeless hermit crab might need it!
Human uses: These beautiful tiny
shells are collected and sold as cheap curious and for handicrafts.
Status and threats: Button shells
were abundant in Singapore in the 1960's, but are now listed as vulnerable
because their habitats have become degraded or were lost. |
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The foot of a
Button shell
Hermit crabs
in Button shells |
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quick
facts
Less than 1cm in diameter, common
Classification:
Class Gastropoda
Phylum Mollusca |
