A Despite its name, the electric eel is more closely related to carp and catﬁsh than to other eels. It produces electricity in electrocytes — special cells arranged like stacks of batteries — found in three separate organs.
The rapid transfer of sodium ions along the length of these electrocytes generates an electrical current at either high or low voltage, depending on the organ producing the charge.
A high-level shock can carry 600 volts (V) at a current of I amp — enough to kill a human (though this rarely occurs). Large doses of bioelectricity are used to deter predators or stun prey, while in murky water, low- level charges aid communication, navigation and prey location.
Certain species of catﬁsh and ray also generate electricity using the same method; catﬁsh
can produce up to 4ooV, rays up to 200V. The ability of these different ﬁsh to produce electricity is a nice example of convergent evolution — the independent development of similar adaptations in unrelated species.