Stichting De Traditie - Electroreception videos    

Ameiurus (Ictalurus) nebulosus (Lesueur, 1819)

- A catfish, Ameiurus (Ictalurus) nebulosus (Lesueur, 1819), catches a Xenopus tadpole in turbid water. The tadpole is swimming near the surface. The catfish is hungry and excited after having smelled water from the tank where the tadpoles were kept. The tadpole is hardly visible near the water surface, and is swimming from left to the right. The light conditions were poor, as in the natural situation. The muddy water was collected from the pond where the catfish was caught.

- A catfish, Ameiurus (Ictalurus) nebulosus (Lesueur, 1819) passes a plastic dummy Xenopus tadpole without noticing it. In spite of the catfish being hungry and aroused by water-that-smells-of-tadpoles, the chemically and electrically inert plastic dummy tadpole is passed without the catfish paying attention. 

- A catfish, Ameiurus (Ictalurus) nebulosus (Lesueur, 1819) catches a plastic dummy Xenopus tadpole which is powered by an electric field that resembles the natural Xenopus bio-electric field. If the dummy, which did not evoke a response earlier, is powered with an electrical stimulus that was recorded earlier from a natural tadpole, the catfish behaves as if it were a real, live tadpole.

The electroreceptor organs by which the electric field is detected have been described by morphologists ages ago. Their function was not clear at the time. Today it is known that  the electroreceptor organs are used for the detection of electrical fields in the microvolt range. Paradoxically, catfish have no electric organs like Gnathonemus  or Apteronotus.  Nevertheless they can feel the very weak electrical fields which all aquatic organisms emanate.

The original recordings were made on super-8 film.
The experiment is described in: Peters-RC, Meek-J 1973.Catfish and electric fields. Experientia (Basel) 29, 299-300. 

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