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Snapping
Shrimp or
Pistol Prawn
Family Alpheidae
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Snap,
crackle and pop! These
little creatures make the incessant pops that you hear at low tide.
They are found everywhere on the sand and mudflats of Chek Jawa and
range from tiny ones to rather large ones that can pack a really loud
pop. Some even hide under carpet anemones.
Snap to it! A snapping shrimp
has one of its pincers is greatly enlarged. This pincer may even be
as long as its entire body! The pincer has a moveable 'finger' held
apart with a catch. When the catch is released, an explosive sound
results. The blast stuns prey like tiny fish and cracks the shells
of small clams. It is also used to ward off predators and intimidate
rival pistol prawns. During the day, the snapping shrimp hides in
a burrow, sometimes renovating it quietly. It forages more actively
at night.
The science of The Sound: The
snapping sound is not made by the fingers actually hitting each other.
Rather, a high-speed jet of water shoots out due to the extremely
rapid compression of the fingers. This jet vapourises the water and
creates a bubble. When the bubble collapses, the sound results. Not
only that, a flash of light is also emitted! These findings are possibly
useful for naval applications as the sound of snapping shrimps seriously
interfere with sonar detection in shallow seas. In fact, snapping
shrimps have been studied since World War II as their sounds interfered
with the detection of hostile submarines!
Colonial shrimps? A kind of snapping
shrimp (Synalpheaus regalis) that lives in sponges in the coral
reefs of Belize were found to form colonies much like termites do.
One 'queen' prawn produces all the members of the colony, which attack
members of other colonies but are peaceful towards members of their
own colony. |
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Some of the snapping shrimps that can be
seen on Chek Jawa |
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quick
facts
2-7cm, common in the seagrass lagoon, coral rubble
Classification:
Order Decapoda
Class Malacostraca
Subphylum Crustacea
Phylum Arthropoda |
