The Role of Magnetic Stimuli in Animals Essay

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In as early as the year 1855 Minddendorf proposed the idea of broad front, one-direction migration also suggested a means of orientation, that birds were capable of detecting the magnetic poles and of maintaining their bearing therefrom. Since then many similar ideas have continued to pop up at random intervals (Carthy 56). An immediate difficulty is the lack of any structure or tissue that could possibly react to the magnetic field. In the year 1948, the discovery of certain forces were indeed produced by placing 'non-magnetic' material in a magnetic field, however they were far too minute to merit any serious consideration (Carthy 59). Some reports speak of heightened locomotor activity and heartbeat, when in close proximity to …show more content…
It must be remembered that no-one has yet been able to give the slightest indication of what the magnetic-sensitive organs are, nor whether they have sufficient acuity for us to be able to speak of a menotaxis, let alone orientation. By contrast, the bird's eye is a very highly developed sense organ. Recent work suggests that European robins do not even detect north from the polarity of the magnetic field but from its angle to the horizon (43). Hypotheses that the earth magnetic field could provide a navigational grid date as far back as the work Viguier completed in 1882. The outcome of his work suggested that birds could detect and measure three components of the field, its intensity, inclination (the angle which a compass needle makes with the horizontal) and declination (the angle between magnetic and geographical north). These three components vary more or less with independence of one another so that their isolines would form a complex grid. Over the next few years, several different scientists restated this hypothesis, with minor variations. The complete lack of evidence for any direct reaction to a magnetic field in birds is a very questionable issue (Carthy 46). Can birds actually use magnetic stimuli as an internal compass? Well Casamajor (1927) and Wodzicki (1939) found that fixing magnets to the head of the Pigeon and the Stork, had no effect on their homing ability. There are many other theoretical difficulties that may

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