Eyes are essential for magnetoreception in a mammal

Abstract

Several groups of mammals use the Earth's magnetic field for orientation, but their magnetosensory organ remains unknown. The Ansell's mole-rat (Fukomys anselli) is a subterranean rodent with innate magnetic orientation behavior. Previous studies proposed that its magnetoreceptors are located in the eye. To test this hypothesis, we assessed magnetic orientation in enucleated mole-rats.Initially, we demonstrate that enucleation of mole-rats does not lead to changes in routine behaviors. We then studied magnetic compass orientation by employing a well-established nest building assay. To ensure that directional responses were based on magnetic parameters, we tested animals under four magnetic field alignments. In line with previous studies, control animals exhibited a significant preference to build nests in magnetic south-east. In contrast, enucleated mole-rats built nests in random magnetic orientations, suggesting an impairment of their magnetic sense. The results provide robust support for the hypothesis that mole-rats perceive magnetic fields with their minute eyes.

Isotope effects on radical pair performance in cryptochrome: a new hypothesis for the evolution of animal migration

“…The RP mechanism could, however, be the same in other animals with magnetic orientation capabilities, as the expression of magneto-sensitive cryptochrome has been shown to occur in the retina of insects [32], and even of humans [33]. The capacity for magnetic orientation has also been shown to reside in the eyes of other mammals [34].…”