Dear MARMAN colleagues,
we are pleased to share with you our recent publication on passive electroreception in bottlenose dolphins in The Anatomical Record’s special issue on marine mammal sensors systems. Our results establish passive electroreception as a supplementary sensory modality in this species that could facilitate short-range prey detection. The fact that the bottlenose dolphins is the second species to have this sense suggests that electroreception might be present in other dolphin species as well. Hüttner, T., Fersen, L. von, Miersch, L., Czech, N. U., & Dehnhardt, G. (2021). Behavioral and anatomical evidence for electroreception in the bottlenose dolphin (Tursiops truncatus). The Anatomical Record. Advance online publication. https://doi.org/10.1002/ar.24773 Abstract: In the order of cetacean, the ability to detect bioelectric fields has, up to now, only been demonstrated in the Guiana dolphin (Sotalia guianensis) and is suggested to facilitate benthic feeding. As this foraging strategy has also been reported for bottlenose dolphins (Tursiops truncatus), we studied electroreception in this species by combining an anatomical analysis of “vibrissal crypts” as potential electroreceptors from neonate and adult animals with a behavioral experiment. In the latter, four bottlenose dolphins were trained on a go/no-go paradigm with acoustic stimuli and afterward tested for stimulus generalization within and across modalities using acoustic, optical, mechanical, and electric stimuli. While neonates still possess almost complete vibrissal follicles including a hair shaft, hair papilla, and cavernous sinus, adult bottlenose dolphins lack these features. Thus, their “vibrissal crypts” show a similar postnatal morphological transformation from a mechanoreceptor to an electroreceptor as in Sotalia. However, innervation density was high and almost equal in both, neonate as well as adult animals. In the stimulus generalization tests the dolphins transferred the go/no-go response within and across modalities. Although all dolphins responded spontaneously to the first presentation of a weak electric field, only three of them showed perfect transfer in this modality by responding continuously to electric field amplitudes of 1.5 mV cm−1, successively reduced to 0.5 mV cm−1. Electroreception can explain short-range prey detection in crater-feeding bottlenose dolphins. The fact that this is the second odontocete species with experimental evidence for electroreception suggests that it might be widespread in this marine mammal group. Best regards, Tim Hüttner
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