Magnetite-based magnetoreception

Orientation, navigation, and homing. are critical traits expressed by organ isms ranging from bacteria through higher vertebrates. Sensory systems that aid such behavior have provided key selective advantages to these groups o ver the past 4 billion years, and are highly evolved;, magnetoreception is no exception. Across many species and groups of organisms, compelling evide nce exists that the physical basis of this response is tiny crystals of sin gle-domain magnetite (Fe3O4). lt is the opinion of the authors that all mag netic field sensitivity in living, organisms, including elasmobranch fishes , is the result of a highly evolved, finely-tuned sensory system based on s ingle-domain, ferromagnetic crystals.