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Electric Rays. Hypnidae species.
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protected: © 2002 Kelvin Aitken.
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Two species of electric rays are found in shallow water and four other
species that are usually picked up by trawlers live in deeper waters.
As the name suggests, all have one asset in common: the ability to deliver
an electric shock, which may be anything from a mild tingle to a body-contorting
blow.
The Numbfish or Numbray, also known as the Coffin Ray (Hypnos monopterygium)
(a name not due to any deadly attributes but to the shape of specimens
that have been dried out in the sun), can be found in shallow water down
to below 200 m. Their brown colouring can vary from pale pink to chocolate,
sometimes with a blotchy or sandy pattern.
Numbfish are usually found buried in sand or silt waiting for they prey
to swim within striking distance. When a crab or fish comes too close
it is hit with an electric charge that stuns it so that the ray can feed
without fear of retaliation or injury. This animal is capable of delivering
a severe electric shock, as many divers and anglers have found, and it
should be left alone.
Numbfish are found camouflaged beneath a layer of sand with just their
eyes and spiracles protruding. To tempt prey to within striking range
some Numbfish have a small black worm that lives on the eye or spiracle.
Its colour is in stark contrast to the sand and it performs a constant
swaying dance which attracts fish to the ray. This is a commensal, not
a parasitic, relationship as both the ray and worm benefit.