Electric activity of the adult European river lamprey

Lampreys possess electroreceptors distributed across their body surface, yet the only previously documented electric signals in these animals were ventilatory myograms, hypothesized to enable short-range electrolocation. Here, we report the discovery of biphasic, spike-like electric signals in free-swimming lampreys, recorded in both moving and immobile individuals. These signals exhibited amplitudes several dozen times greater than ventilatory signals, with durations approximately half as long. The spike-like pulses were not related to any detectable movements but were tightly linked to specific behavioral contexts. Most were generated upon physical contact with another lamprey or a substrate, with their source consistently located near the point of contact rather than at a fixed position within the body. Signals produced by immobile individuals in response to external stimuli differed significantly from those generated by moving individuals upon contact with a substrate. Our estimates suggest that these signals have sufficient amplitude to actively probe the surroundings, at least within several centimeters of the body.