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Wednesday, June 22, 2011

The Beauty Of The Electric Ray


Beauty Of Animlas | The Beauty Of The Electric Ray | The electric rays are a group of rays, flattened cartilaginous fish with enlarged pectoral fins, comprising the order Torpediniformes. They are known for being capable of producing an electric discharge, ranging from as little as 8 volts up to 220 volts depending on species, used to stun prey and for defense. There are 69 species in four families. Perhaps the best known members are those of the genus Torpedo, also called crampfish and numbfish, after which the device called a torpedo is named. The name comes from the Latin torpere, to be stiffened or paralyzed, referring to the effect on someone who handles or steps on a living electric ray. With their thick, flabby bodies and short tails, torpedo rays are poor swimmers. Their disk-shaped bodies allow them to remain suspended in the water or roam with minimal swimming effort.

Electric rays have a rounded pectoral disc with two moderately large rounded-angular (not pointed or hooked) dorsal fins (reduced in some narkids), and a stout, muscular tail with a well-developed caudal fin. The body is thick and flabby, with soft, loose skin devoid of dermal denticles and thorns. A pair of kidney-shaped electric organs are found at the base of the pectoral fins. The snout is broad, large in the Narcinidae but reduced in all other families. The mouth, nostrils, and five pairs of gill slits are located underneath the disc.

Electric rays are found from shallow coastal waters down to at least 1,000 metres (3,300 ft) depth. They are sluggish and slow moving, propelling themselves along with their tails, rather than using their disc-shaped bodies, as other rays do. They feed on invertebrates and small fish. They lie in wait for prey below the sand or other substrate, using their electricity to stun and capture it.

The electrogenic properties of electric rays have been known since antiquity. The ancient Greeks used electric rays to numb the pain of childbirth and operations. In his dialogue Meno, Plato has the character Meno accuse Socrates of "stunning" people with his puzzling questions, in a manner similar to the way the torpedo fish stuns with electricity. Scribonius Largus, a Roman physician, recorded the use of torpedo fish for treatment of headaches and gout in his Compositiones Medicae of 46 AD. The torpedo fish, or electric ray, appears continuously in premodern natural histories as a magical creature, and its ability to numb fisherman without seeming to touch them was a significant source of evidence for the belief in occult qualities in nature during the ages before the discovery of electricity as an explanatory mode.

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