Ancient Web: Caltech's Electric Fish Lab Colored Invisible Fields in QuickTime

Part of the Ancient Web Collection.

An electric fish can sense its environment using a field humans cannot see. A Caltech research group found a way to make the field visible, then shared the results as downloadable QuickTime movies.

Visit the Weakly Electric Fish research homepage.

The page credits Chris Assad and Brian Rasnow, who studied electroreception in the Bower lab at the California Institute of Technology from 1987 to 1999. Their questions were practical and fascinating: how do fish produce electric signals, how do objects alter the field, and how does the animal's nervous system use that information?

The website introduces several weakly electric species, including black ghost and brown ghost knifefish. A photograph of a fish eating worms is followed by links for a primer, movies, computer simulations, behavior and publications. It feels like a laboratory open house prepared by the researchers taking the measurements.

Five million readings become an animation

The QuickTime page explains how the team mapped electric-organ discharges. Small electrodes were moved through hundreds of positions around a fish, recording waveforms and then aligning and interpolating measurements into color images.

The researchers say that producing one movie required roughly five million measurements and a hundred million floating-point operations. The work used custom electronics, MATLAB, and a Macintosh IIfx. Colors indicate electric potentials; the animations play thousands of times slower than the actual signals.

The downloadable files bear the marks of the 1990s. A visitor could obtain QuickTime MOV movies or BinHex HQX versions for Macintosh distribution. The page explains why special playback software might be needed, and its footer says it was last modified September 30, 1996.

A computer-simulation section, marked February 1997, shows three-dimensional fish models, calculated fields and disturbances created by nearby objects. The authors describe some results as work still being prepared for publication; that statement does not confirm the promised paper appeared.

The presentation is inseparable from its period. A GIF thumbnail, a BinHex download and a small paragraph carried a scientific visualization that today might live inside an interactive browser.

Explore the electric-field movies and original measurement notes.

Part of the Ancient Web Collection.