Saturday, June 25, 2011

Electric Rays

The shocks produced by these fish can be painful but are unlikely to be fatal to humans. A special part of the ray’s brain regulates how and when the fish is able to give a shock.

Electric Rays
The ability of electric rays to inflict shocks was well known centuries before the power of electricity was understood. Their electrical output is about 220 volts; much less than that of the electric eel; so they do not represent a serious danger to humans.

Electric Rays
The electrical organs of these fish are located on each side of the body. They have evolved from muscles. These have developed the ability to generate a much stronger electrical current than those that normally travel along the nerves in the body triggering ordinary muscles movements. The ray’s electrical organs consist of layers of disks packed with a jellylike substance along which an electric charge can pass. Up to a thousand of these layers are stacked on top of each other throughout the body.

Brain Power
Electric Rays
A special part of the Electric Ray's brain called the electrical lobe connects directly via nerve fibers to the electrical organs. This in turn enables the ray to control the use of its electricity efficiently. It only discharges when its
prey is within reach or danger threatens.

This is important, because as with a battery, the voltage from the electrical organs will become drained if they are used all the time. It takes time for them to recharge. There is also an instant override in the system. When female rays give birth, for example, they will not electrocute their own offspring.


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