Date Published: October 23, 2017
Publisher: Public Library of Science
Author(s): Gregory C. Nordmann, Tobias Hochstoeger, David A. Keays
Abstract: Evolution has equipped life on our planet with an array of extraordinary senses, but perhaps the least understood is magnetoreception. Despite compelling behavioral evidence that this sense exists, the cells, molecules, and mechanisms that mediate sensory transduction remain unknown. So how could animals detect magnetic fields? We introduce and discuss 3 concepts that attempt to address this question: (1) a mechanically sensitive magnetite-based magnetoreceptor, (2) a light-sensitive chemical-based mechanism, and (3) electromagnetic induction within accessory structures. In discussing the merits and issues with each of these ideas, we draw on existing precepts in sensory biology. We argue that solving this scientific mystery will require the development of new genetic tools in magnetosensitive species, coupled with an interdisciplinary approach that bridges physics, behavior, anatomy, physiology, molecular biology, and genetics.
Partial Text: Invented by the Chinese between 200 BC and 100 AD, the compass was first exploited by mariners as a tool around 1000 AD . Coupled with early star charts, it ushered in an era of exploration as humanity set sail for the horizon . Yet for thousands, perhaps millions of years prior, evolution had equipped life on the planet with a biological global positioning system that was far superior to those early navigational aids. A system that guided the artic tern on its annual migration from its rookeries in Greenland to the plentiful feeding grounds in Weddal Bay in Antarctica (and back again; Fig 1A and 1D) . A biological apparatus that enabled female loggerhead turtles after spending their juvenile life at sea, to return to the very same beach where they hatched more than 10 years ago (Fig 1B and 1D) . A sense that was utilized by pigeons as they delivered microfilm, strapped precariously to their tiny feet, as the city of Paris lay siege to the Prussians in the 19th century (Fig 1C and 1D). It was the Russian zoologist Alexander von Middendorff who was amongst the first to speculate that these animals might use the Earth’s magnetic field as a navigatory cue: