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Electric fish measure distance in the dark


Distance determination in animals can be achieved by visual or non-visual cues1. Weakly electric fish use active electrolocation for orientation in the dark2. By perceiving self-produced electric signals with epidermal electroreceptors, fish can detect, locate and analyse nearby objects. Distance discrimination, however, was thought to be hardly possible because it was assumed that confusing ambiguity could arise with objects of unknown sizes and materials3,4,5. Here we show that during electrolocation electric fish can measure the distance of most objects accurately, independently of size, shape and material. Measurements of the ‘electric image’ projected onto the skin surface during electrolocation6,7,8 revealed only one parameter combination that was unambiguously related to object distance: the ratio between maximal image slope and maximal image amplitude. However, slope-to-amplitude ratios for spheres were always smaller than those for other objects. As predicted, these objects were erroneously judged by the fish to be further away than all other objects at an identical distance. Our results suggest a novel mechanism for depth perception that can be achieved with a single, stationary two-dimensional array of detectors.

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Figure 1: a, Electric image size and amplitude change with object distance.
Figure 2: Psychometric functions for distance discrimination of (a) two identical metal cubes (64 cm3), (b) two identical metal spheres (33.5 cm3) and (c) two metal cubes of different sizes (125 and 27 cm3).
Figure 3: Electric image measurements.
Figure 4: Psychometric functions for distance discrimination of a metal sphere and a metal cube, and for two identical metal cubes.


  1. Collett, T. S. & Harknes, L. I. K. in Analysis of Visual Behaviour (eds Ingle, D. J., Goodale, M. A. & Mansfield, J. W.) 111–175 (MIT Press, 1982).

    Google Scholar 

  2. Lissmann, H. W. & Machin, K. E. The mechanism of object location in Gymnarchus niloticus and similar fish. J. Exp. Biol. 35, 451–486 (1958).

    Google Scholar 

  3. von der Emde, G. in The Physiology of Fishes (ed. Evans, D. H.) 313–343 (CRC, Boca Raton, 1998).

    Google Scholar 

  4. Bastian, J. in Comparative Perception (eds Stebbins, W. C. & Berkeley, M. H.) 35–89 (Wiley, New York, 1989).

    Google Scholar 

  5. Schwarz, S. Diplomarbeit, Institut für Zoologie, Universität Bonn (1997).

  6. Heiligenberg, W. Electrolocation of objects in the electric fish Eigenmannia (Rhamphichthyidae, Gymnotoidei). J. Comp. Physiol. 87, 137–164 (1973).

    Article  Google Scholar 

  7. Caputi, A., Budelli, R., Grant, K. & Bell, C. C. The electric image in weakly electric fish. II Physical images of resistive objects in Gnathonemus petersii. J. Exp. Biol. 201, 2115–2128 (1998).

    CAS  PubMed  Google Scholar 

  8. Rasnow, B. The effects of simple objects on the electric field of Apteronotus. J. Comp. Physiol. A. 178, 397–411 (1996).

    Google Scholar 

  9. Howard, I. P. & Rogers, B. J. Binocular Vision and Stereopsis (Oxford Univ. Press, New York, 1995).

    Google Scholar 

  10. Collett, T. Stereopsis in toads. Nature 267, 349–351 (1977).

    ADS  CAS  Article  Google Scholar 

  11. Kral, K. & Poteser, M. Motion parallax as a source of distance information in locusts and mantids. J. Insect Behav. 10, 145–163 (1997).

    Article  Google Scholar 

  12. Lehrer, M., Wehner, R. & Srinivasan, M. V. Motion cues provide the bee's visual world with a third dimension. Nature 332, 356–357 (1988).

    ADS  Article  Google Scholar 

  13. Schuif, A. & Hawkins, A. D. Acoustic distance discrimination by the cod. Nature 302, 143–144 (1983).

    ADS  Article  Google Scholar 

  14. Bleckmann, H. Reception of Hydrodynamic Stimuli in Aquatic and Semiaquatic Animals (Gustav Fischer, Stuttgart, 1994).

    Google Scholar 

  15. Atema, J. Eddy chemotaxis and odor landscapes: exploration of nature with animal sensors. Biol. Bull. 191, 129–138 (1996).

    CAS  Article  Google Scholar 

  16. Moller, P., Serrier, J., Belbenoit, P. & Push, S. Notes on the ethology and ecology of the Swashi river mormyrids (Lake Kainji, Nigeria). Behav. Ecol. Sociobiol. 4, 357–368 (1979).

    Article  Google Scholar 

  17. von der Emde, G. The sensing of electric capacitances by weakly electric mormyrid fish: effects of water conductivity. J. Exp. Biol. 181, 157–173 (1993).

    Google Scholar 

  18. Tippler, P. A. Physik (Spektrum Akademischer, Heidelberg, (1994).

    Google Scholar 

  19. von der Emde, G. & Bleckmann, H. Finding food: senses involved in foraging for insect larvae in the electric fish, Gnathonemus petersii. J. Exp. Biol. 201, 969–980 (1998).

    Google Scholar 

  20. Wagner, H. Flow-field variables trigger landing in flies. Nature 297, 147–148 (1982).

    ADS  Article  Google Scholar 

  21. Hassan, E. S. in The Mechanosensory Lateral Line. Neurobiology and Evolution (eds Coombs, S., Görner, P. & Münz, H.) 217–228 (Springer, Berlin, 1989).

    Book  Google Scholar 

  22. Bleckmann, H., Tittel, G. & Blübaum-Gronau, E. in The Mechanosensory Lateral Line. Neurobiology and Evolution (eds Coombs, S., Görner, P. & Münz, H.) 501–526 (Springer, Berlin, 1989).

    Book  Google Scholar 

  23. Harkness, L. Chameleons use accommodation cues to judge distance. Nature 267, 346–349 (1977).

    ADS  CAS  Article  Google Scholar 

  24. Hopkins, C. D. Temporal structures of non-propagated electric communication signals. Brain Behav. Evol. 28, 43–59 (1986).

    CAS  Article  Google Scholar 

  25. Suga, N., Butman, J. A., Teng, H., Yan, J. & Olsen, J. F. in Active Hearing (eds Flock, A., Ottoson, D. & Ulfendahl, M.) 13–30 (Pergamon, New York, 1995).

    Google Scholar 

  26. Schnitzler, H.-U., Menne, D. & Hackbarth, H. in Time Resolution in Auditory Systems (ed. Michelsen, A.) 180–204 (Springer, Berlin, 1985).

    Book  Google Scholar 

  27. Dear, S. P., Simmons, J. A. & Fritz, J. Apossible neuronal basis for representation of acoustic scenes in auditory cortex of the big brown bat. Nature 364, 620–623 (1993).

    ADS  CAS  Article  Google Scholar 

  28. Cialo, S., Gordon, J. & Moller, P. Spectral sensitivity of the weakly discharging electric fish Gnathonemus petersii using its electric organ discharges as the response measure. J. Fish Biol. 50, 1074–1087 (1997).

    Google Scholar 

  29. Zar, J. H. Biostatistical Analysis (Prentice Hall, Englewood Cliffs, 1984).

    Google Scholar 

  30. Hoerl, A. E. J in Chemical Business Handbook (ed. Perry, J. H.) 20–50 (McGraw-Hill, London, 1954).

    Google Scholar 

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The behavioural experiments and the analysis of the electric images were performed by S.S. during work for his diploma thesis. We thank H. Bleckmann for providing laboratory space and for his continuous support throughout this study; C. C. Bell, H. Bleckmann, J. Mogdans, S. F. Perry, F. Schaeffel and H. Wagner for critically reading the manuscript and helpful discussions; C. Gutzen for help with the figures; and W. Alt for statistical advice. G.v.d.E. is a recipient of a Heisenberg stipend of the DFG. This work was financed partly by a research grant from the EC to K.G. by the Franco-German international exchange programme PROCOPE, by the Franco-Uruguayan exchange programme ECOS and by a doctoral fellowship to L.G. from the French Ministry of Foreign Affairs.

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Correspondence to Gerhard von der Emde.

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von der Emde, G., Schwarz, S., Gomez, L. et al. Electric fish measure distance in the dark. Nature 395, 890–894 (1998).

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