DOI: 10.5061/dryad.b2rbnzsn2
title: Passive electroreception in bottlenose dolphins Tursiops truncatus: implication for micro- and large-scale orientation

description: For the two dolphin species Sotalia guianensis and Tursiops truncatus, it
 was shown that the vibrissal crypts located on the rostrum represent
 highly innervated, ampullary electroreceptors and that both species are
 correspondingly sensitive to weak electric fields. For a comparative
 assessment of the sensitivity of the bottlenose dolphin's
 electroreceptive system, we determined detection thresholds for DC and AC
 electric fields with two bottlenose dolphins. In a psychophysical
 experiment, the animals were trained to respond to electric field stimuli
 using the go/no-go paradigm. We show that bottlenose dolphins are able to
 detect DC electric fields as low as 2.4 &[mu]V cm -1 and
 5.5 &[mu]V cm -1, respectively, a detection threshold in the same
 order of magnitude as those in the platypus and the Guiana dolphin.
 Detection thresholds for AC fields (1, 5, and 25 Hz) were generally higher
 than those for DC fields, and the sensitivity for AC fields decreased with
 increasing frequency. Although the electroreceptive sensitivity of
 dolphins is lower than that of elasmobranchs, it is suggested that it
 allows orientation at micro and large scales. In dolphins pursuing benthic
 foraging strategies, electroreception may facilitate short-range prey
 detection and target-oriented snapping of their prey. Furthermore, we
 discuss that the ability to detect weak electric fields may enable
 dolphins to detect the Earth's magnetic field through induction-based
 magnetoreception, thus allowing large-scale orientation.
description: <strong>Description</strong> Data
 of the paper at JEB. The files contain experimental
 data for both animals testing their abilities to detect DC and AC electric
 fields in water and videos. After a preliminary study
 (Hüttner et al., 2022) demonstrated passive electroreception in bottlenose
 dolphins, the present study aimed to evaluate the sensitivity of
 bottlenose dolphins to weak electric fields in water (DC and low-frequency
 AC stimuli). The present data show that the two
 dolphins learned to reliably respond to electric field stimuli that could
 benefit them during prey detection or large-scale orientation using
 induction-based magnetoreception.
 <br><strong>Dataset
 includes:</strong> Performances are shown in
 percent (%). Electric field strength was reduced if the dolphin's
 performance (hit rate) remained &gt; 80 % hits over at least 30 trials
 of this electric field strength. 1) Performance of
 dolphins Donna and Dolly during DC detection tests including
 Performance (hit rate) over last 30 trials for each
 tested electric field strength (500 µV cm<sup>-1</sup> - 2 µV
 cm<sup>-1</sup>) false alarm rate during
 these sessions performance of all electric field
 trials of each tested electric field strength overall
 performance (correct responses on all go & no-go
 trials) 2) Performance of dolphin Donna
 during AC detection tests including 
 Performance (hit rate) over last 30 trials for each tested
 electric field strength for each tested AC frequency (1 Hz, 5 Hz, and 25
 Hz) false alarm rate during these sessions
 performance of all electric field trials of each tested electric
 field strength overall performance (correct responses
 on all go & no-go trials) 3)
 Performance of dolphin Dolly during AC detection tests
 Performance (hit rate) over last 30 trials for each
 tested electric field strength for each tested AC frequency (1 Hz and 5
 Hz) false alarm rate during these sessions
 performance of all electric field trials of each tested electric
 field strength overall performance (correct responses
 on all go & no-go trials) 
 <strong>Videos include:</strong> 
 Example video of a no-go trial: Donna showing a correct response
 on a no-go trial (correct rejection). After Donna enters the apparatus and
 stations correctly on the target and the resting platform she remains
 calmly inside the apparatus for a predefined of 12 s. The experimenter
 (TH) then gives a short whistle sound (secondary reinforcement, not
 audible) and Donna leaves the apparatus and receives a fish reward from
 the trainer sitting on the other side of the poll (not
 visible). Example of a go trial with electric field
 stimulus: Donna correctly responding to an electric stimulus-present trial
 with an electric field strength of 5 µV cm<sup>-1</sup>. After
 the station correctly inside the apparatus, the experimenter (TH) presents
 the electric stimulus. Within 5 s after the stimulus onset, Donna leaves
 the station and exits the apparatus. This so-called hit was also
 secondarily reinforced with a short whistle sound by the experimenter
 followed by a fish reward from the trainer.