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Fan
shell
Family Pinnidae |
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Fan shells are quite large and relatively common on the sandy parts
of the seagrass lagoon and coral rubble area. However, they are often
overlooked as most of the shell is often buried.
Buried fan: The fan shell has
a thin but strong shell. It buries itself, pointed end down and anchored
by attaching byssus threads to buried rocks and stones. Its broader,
razor sharp edge sticks out above the ground and can seriously cut
those who walk about barefoot. If the edge is damaged, the animal
merely repairs it so it remains razor sharp. Its major organs are
small and located at the narrower end buried in the sand where it
is difficult for most predators to reach.
Fan food: Like other bivalves,
Fan shells are filter feeders. At high tide, they open their shells
a little. A current of water is generated through their shell and
they sieve out the food particles with their enlarged gills. When
exposed at low tide, they clamp up their shells tightly.
Role in the ecosystem: Like us
humans, many other animals like to eat Fan shells, if they can pry
the shell apart. All manner of seaweeds and encrusting animals often
settle on the portions of the Fan shell that sticks out above the
sand. These provide food and shelter for small animals. A parasitic
crab is also sometimes found in some species of Fan shells.
Human uses: Fan shells are edible
and were once plentiful in Singapore and collected as food. It is
said that in the past, people collected the long, golden byssus threads
of the Noble pen shell (Pinna nobilis), a fan shell found in
the Mediterranean. The threads were woven into a fine 'cloth of gold'.
Some suggest that the 'Golden Fleece' of Greek mythology was made
out of the byssus threads of this shell. Some other Fan shells had
byssus hairs that were so similar to human hair that people refused
to eat them.
Status and threats: Fan shells
are now less common in Singapore. |
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quick
facts
About 10cm long, sometimes seen
Classification:
Class Bivalvia
Phylum Mollusca |
