Quote:
Originally Posted by southern151
You have an English version of this?!
BTW, I think it's great that you get to spend the amount of time you do with your kids in the name of science. Teaching from two angles is certainly admirable! 
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Electroreception: Many species of fish, including catfish, are known to be able to detect electric fields. In some cases, the detection of electric fields is used to detect nerve impulses in prey species and it assists in locating prey. In some cases, the ability to detect electromagnetic fields, combined with the ability to generate larger fields than produced by ordinary nerve impulses (known as electrogeneration) may be used to assist some species in locating mates.
In other cases, fish may combine electroreception in salt water to detect magnetic fields. The law of electromagnet induction tells us that an electric field is induced by a conductor (salt water) moving in a magnetic field. Some fishes with the most sensitive electroreception may be able to detect the earth's magnetic field this way.
Several scientists have shown that some elasmobranches (sharks and rays) are deterred from biting magnetic hooks, presumably because their sensitive electroreception is able to detect the magnetic field. But these scientists have opined that magnetic hooks will not deter teleost fishes (bony fishes, which includes most species of commercial and recreational interest) from biting because they lack sufficiently sensitive electroreception. Whether or not bony fishes have sufficiently sensitive electroreception to be deterred by magnetic hooks is the question we are working on. The hardhead catfish simply combines a number of features to be a convenient test species.