Spooky Interaction at a Distance in Cave and Surface Dwelling Electric Fishes

Frontiers in Integrative Neuroscience

Nicole Andanar¹  Daphne Soares¹  Eric S. Fortune¹  Maria Elina Bichuette²  Manu Madhav³  Noah J. Cowan³  Ravikrishnan P. Jayakumar³ 

[1] Biological Sciences, New Jersey Institute of Technology, Newark, NJ, United States;Departamento de Ecologia e Biologia Evolutiva, Universidade Federal de São Carlos, São Carlos, Brazil;Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD, United States;

关键词: gymnotiformes;    weakly electric fish;    troglobitic;    epigean;    envelope;    cavefish;   

DOI  :  10.3389/fnint.2020.561524

来源: DOAJ

【 摘 要 】

Glass knifefish (Eigenmannia) are a group of weakly electric fishes found throughout the Amazon basin. Their electric organ discharges (EODs) are energetically costly adaptations used in social communication and for localizing conspecifics and other objects including prey at night and in turbid water. Interestingly, a troglobitic population of blind cavefish Eigenmannia vicentespelea survives in complete darkness in a cave system in central Brazil. We examined the effects of troglobitic conditions, which includes a complete loss of visual cues and potentially reduced food sources, by comparing the behavior and movement of freely behaving cavefish to a nearby epigean (surface) population (Eigenmannia trilineata). We found that the strengths of electric discharges in cavefish were greater than in surface fish, which may result from increased reliance on electrosensory perception, larger size, and sufficient food resources. Surface fish were recorded while feeding at night and did not show evidence of territoriality, whereas cavefish appeared to maintain territories. Surprisingly, we routinely found both surface and cavefish with sustained differences in EOD frequencies that were below 10 Hz despite being within close proximity of about 50 cm. A half century of analysis of electrosocial interactions in laboratory tanks suggest that these small differences in EOD frequencies should have triggered the “jamming avoidance response,” a behavior in which fish change their EOD frequencies to increase the difference between individuals. Pairs of fish also showed significant interactions between EOD frequencies and relative movements at large distances, over 1.5 m, and at high differences in frequencies, often >50 Hz. These interactions are likely “envelope” responses in which fish alter their EOD frequency in relation to higher order features, specifically changes in the depth of modulation, of electrosocial signals.

【 授权许可】

Unknown