Summary
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1.
The orientation of fresh-water snails (Physa pomillia) in a symmetrical magnetic field was studied from February to March and from September to October, 1965, during the hours 8:30 to 17:30.
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2.
The orientation of the snails was studied in an augmented magnetic field, 9 times that of the earth's field at Gainesville, Florida, with a bar magnet aligned parallel and at right angles to the earth's magnetic field. Control experiments were performed with the bar magnet removed from the apparatus. Possible effects of the magnetic field were tested under two different light conditions, using a window centered above the orientation platform, and one placed above and ahead of it.
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3.
Under the given experimental conditions the snails showed no significant right- or left-turning.
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4.
The time of year did not appear to affect the behavior of the snails in the arena.
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5.
Snails moving in the uniformly diffuse light from the centered window scattered over the whole range of the arena. Snails in the light gradient caused by the eccentric window oriented toward the point on the floor of the arena at which the light intensity was greatest (positive phototaxis).
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6.
Physa pomillia did not orient with respect to the direction and strength of the magnetic fields used.
Zusammenfassung
Im Frühjahr und Herbst 1965 wurde das Orientierungsverhalten der Süßwasserschnecke Physa pomillia in einem künstlichen, von einem Stabmagneten erzeugten Magnetfeld untersucht, das dem Neunfachen des natürlichen Magnetfeldes am Untersuchungsort in Gainesville, Florida entsprach. Der Stabmagnet war im Versuchsapparat unter der Arena parallel und im rechten Winkel zum Magnetfeld der Erde angebracht; in Kontrollversuchen wurde er entfernt.
Die Versuche wurden in diffusem Licht unter einem exakt über der Lauffläche zentrierten Fenster und, zur Kontrolle von möglichen Beeinflussungen des Orientierungsverhaltens durch ein schwaches Lichtgefälle, unter einem der Arena vorgelagerten Fenster durchgeführt. Letztere Anordnung entsprach den Angaben anderer Autoren (l.c.).
Im Gefälle des exzentrisch angeordneten diffusen Lichtes waren die Schnecken zur Stelle größter Lichtintensität im Sinne einer positiven Phototaxis orientiert. Im zentriert diffusen Licht waren sie in jeder Versuchssituation mit oder ohne Stabmagnet unorientiert. Eine Orientierung der Schnecken nach den Magnetfeldern war nicht nachzuweisen. Die einzelnen Versuchsbefunde stimmten in beiden Jahreszeiten überein.
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Research project performed in fulfillment of the requirements for Ethology (Zy 671) and Animal Orientation and Biological Clocks (Zy 690) under the direction of E. G. F. Sauer, Department of Zoology, University of Florida, Gainesville, Florida 32601.
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Badman, D.G. Effects of light on the orientation of the snail Physa pomillia in a weak magnetic field. Psychol. Forsch. 29, 360–371 (1966). https://doi.org/10.1007/BF00421756
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DOI: https://doi.org/10.1007/BF00421756