The trigeminal cranial nerve of rainbow trout helps them detect magnetic fields by containing magnetosensitive nerve fibers.
"In 1997, the first known magnetoreceptors -- directly linking magnetite to neural connections and activity -- were found in vertebrates. A team of zoologists from Auckland University, led by Dr. Michael Walker, had been studying this mysterious sense in trout, and knew that a region of its skull contained magnetite.
"Recording neural activity from that region, they discovered that a specific subgroup of nerve fibers within a branch of the trigeminal cranial nerve called the ros V nerve fired in response to changes in the surrounding magnetic field. They also found magnetite in a tissue layer directly beneath the trout's olfactory (smell) organs. When they injected a colored dye into the ros V nerve's newly exposed magnetosensitive fibers, the dye revealed that the fibers terminated and ramified all around the magnetite-containing cells within the trout's olfactory tissue." (Shuker 2001:46)
Learn more about this functional adaptation.
- Shuker, KPN. 2001. The Hidden Powers of Animals: Uncovering the Secrets of Nature. London: Marshall Editions Ltd. 240 p.
- Bohannon, J. 2007. MICHAEL WALKER: Seeking Nature's Inner Compass. Science. 5852(318): 904-907.
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