ELECTRIC AND MAGNETIC SENSES 



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(d) 



flounder, Scyliorhinus no longer aims directly at its food in the agar chamber, but 

 searches the area where the seawater flow comes up through the sand. (D) When the 

 chamber is covered with a thin polyethylene film, which is mechanically negligible 

 compared to the stiff agar roof, but offers an extremely high electrical resistance, 

 Scyliorhinus does not detect the live flounder any longer either. (E) Eventually, when 

 the flounder's bioelectric field is simulated by passing a weak electrical current between 

 two electrodes buried in the sand, Scyliorhinus responds to the source of the field from 

 the same distance and with the same vigor as if it were the actual prey (Kalmijn 1971). 



