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Why animals respond to the full moon: Magnetic hypothesis
Bioscience Hypotheses (2009) 2, 399e401
available at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/bihy
Why animals respond to the full moon: Magnetic hypothesis Tsutomu Nishimura a,*, Masanori Fukushima b a
Translational Research Center, Graduate School of Medicine, Kyoto University, Shogoin Kawahara-cho 54, Sakyo-ku, Kyoto 606-8507, Japan b Translational Research Informatics Center, 1-5-4 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047, Japan Received 22 April 2009; received in revised form 10 June 2009; accepted 13 June 2009
KEYWORDS Full moon; Animal behavior; Geomagnetic field
Abstract The geomagnetic field is typically about 50 mT (range 20e90 mT). Geomagnetic activity generally decreases by about 4% for the seven days leading up to a full moon, and increases by about 4% after the full moon, lasting for seven days. Animals can clearly detect the changes in magnetic field intensity that occur at full moon, as it has been shown that variations of just a few tens of nT are adequate to form a useful magnetic ‘map’. We think that moonlight increases the sensitivity of animals’ magnetoreception because the radical pair model predicts that magnetoreception is light dependent. In fact, there have been some reports of changes in the sensitivity of magnetoreception with lunar phase. We propose a hypothesis that animals respond to the full moon because of changes in geomagnetic fields, and that the sensitivity of animals’ magnetoreception increases at this time. ª 2009 Elsevier Ltd. All rights reserved.
The effects of phases of the moon on human and animal nature and behavior are well documented. Crime rates, crisis incidence, human aggression, and animal bites to humans are all positively correlated with the phases of the moon [1e6]. In particular, increases in violent behavior in psychiatric settings have been attributed to the full moon [4e6]. Changes in both moonlight and attractive forces occur at full moon. An effect of moonlight intensity would seem the more obvious explanation for changes in animal behavior at this time. However, there is no plausible explanation for
* Corresponding author. Tel.: þ81 75 751 3397; fax: þ81 75 751 3399. E-mail address: [email protected] (T. Nishimura).
why the increased light intensity causes violent behavior, because moonlight (reflected sunlight, particularly longwavelength (yellow and red) light) and diurnal sunlight include similar wavelengths. Also, the incidence of murder is not influenced by seasonality, even in summer when the duration of sunshine is longer [7]. Thus, an alternative theory is needed. Lieber proposed a theory of biological tides, which has two elements: the direct effect of the moon’s gravitational pull on living organisms and indirect effects of the moon mediated by the Earth’s electromagnetic field [8], although detailed data on changes in the Earth’s electromagnetic field were not mentioned in his book. We have researched geomagnetic field changes and changes in animals’ magnetoreception that occur with lunar phases. We propose a hypothesis that animals respond
1756-2392/$ - see front matter ª 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.bihy.2009.06.006
400 to the full moon because of changes in geomagnetic fields and that sensitivity to magnetoreception increases at full moon. The geomagnetic field is typically about 50 mT (range 20e90 mT). Geomagnetic activity generally decreases by about 4% for the seven days leading up to a full moon, and increases by about 4% after the full moon, lasting for seven days [9]. Geomagnetic fields also change during geomagnetic storms. Sudden fluctuations during big geomagnetic storms, due to the superposition of equatorial ring current effects and auroral current effects, can be observed for 1 2 days. These produce field variations as large as 200 300 nT at low latitudes and can exceed 1000 nT at high latitudes [10]. There are some reports that the violence of animals, including humans, increases during the full moon, as described above, and there have also been reports of relationships between human violence and geomagnetic disturbances. For example, a study in Canada showed that geomagnetic disturbances were significantly correlated with minor violence in a psychiatric prison (P Z 0.01), women’s prison (P Z 0.01) and in one medium-security prison (P Z 0.02) [11]. Thus, both the full moon and geomagnetic disturbances are associated with increased violence in humans. Many animals have the ability to detect changes in magnetic field (magnetoreception). In their review of magnetoreception in animals, Wiltschko and Wiltschko presented evidence that animals from a wide range of taxa possess magnetic sense and use magnetic compasses to navigate [12]. Such taxa include mollusks, crustaceans, insects, fish, birds, mammals and amphibians [12]. Animals can clearly detect the changes in magnetic field intensity that occur at full moon, as it has been shown that variations of just a few tens of nT are adequate to form a useful magnetic ‘map’ [13]. Walker and colleagues (1997) reported that thresholds of 10e200 nT have been shown experimentally in some birds [14] and honeybees [15], and inferred for homing pigeons [16] and whales [17,18]. Two hypotheses for magnetoreception are currently discussed: one proposes a chemical compass based on a radical pair mechanism; the other postulates processes involving magnetite particles [19]. Kirschvink and Kobayashi-kirschvink have detected magnetite particles in a variety of tissues from the human brain [20]. The radical pair model predicts that magnetoreception is light dependent, and light is indeed required for magnetic compass orientation in birds and salamanders [19]. In salamanders, light dependent magnetoreception was found to be located in the pineal gland, the ancient ‘third eye’ of vertebrates [21]. In fact, there have been many reports that changes in the electromagnetic field disrupt the nocturnal production of melatonin in the pineal gland of humans [22]. Although, in general, humans cannot feel geomagnetic field changes, the electroencephalogram (EEG) has been shown to respond to geomagnetic field changes [23]. For example, Belov and colleagues found a positive correlation between EEG synchronization parameters and geomagnetic activity [23]. Thus, humans appear to be influenced by the geomagnetic field. We speculate that moonlight increase the sensitivity of animal magnetoreception because the radical pair model
T. Nishimura, M. Fukushima predicts that magnetoreception is light dependent [19]. The first evidence for this came from behavioral experiments with young homing pigeons: birds displaced in total darkness were disoriented, just as young pigeons displaced in a distorted magnetic field are [19]. Disorientation in the absence of visible light was also observed in the salamander Notophthalmus viridescens [19]. Many studies revealed a wavelength dependence of the magnetic compass in amphibians, migratory birds and pigeons [19]. The effects of light on magnetic orientation are different in birds and newts e birds are disorientated at wavelengths longer than 590 nm [24]. Evidence from shoreward-orienting salamanders demonstrates that salamanders perceive a 90 counterclockwise shift in the direction of the magnetic field under long-wavelength (>500 nm) light [21], which corresponds to moonlight (reflected sunlight, particularly longwavelength (yellow and red) light). These differences could be explained by the different lifestyles of birds, which are diurnal, and salamanders, which are nocturnal. Thus, birds do not need to use moonlight whereas salamanders need to use moonlight-dependent magnetoreception when moving around at night. Thus, animals may have developed wavelength-dependent magnetoreception depending on whether they are diurnal or nocturnal. The effect of wavelength on magnetic orientation in mammals is unclear. Mesozoic mammals are commonly portrayed as shrew- or rat-sized animals that were mainly insectivorous, probably nocturnal and lived in the shadow of dinosaurs [25]. Ancestors of mammals were nocturnal. Then, mammal’s magnetoreception may also have responded to moonlight, particularly at the full moon. Moonlight may increase the sensitivity of animal magnetoreception. In fact, there has been one report of changes in the sensitivity of magnetoreception with lunar phase [26]. Lohmann and Willows showed that the marine opisthobranch mollusk Tritonia diomedea aligned itself eastwards, and the rate of steering eastwards was highest at full moon [26]. A similar tendency in directional phenomena has been reported in mud snails [27]. These results support the assumption that the sensitivity of animals’ magnetoreception increases at full moon. It is important to distinguish between the effects of changes in magnetic field strength and moonlight intensity. One way to test our theory that the magnetic field strength is the critical factor would be to investigate the relationship between moon phase and violent behavior, as Lieber and Agel researched [8]. We need to measure geomagnetic changes in cities where there is high ambient light, abolishing an influence of moonlight. If changes in geomagnetic field strength correlate with increases in violent behavior at times other than at full moon, this might suggest an effect of geomagnetic field changes. In addition, measurement of the illumination intensity or spectrum of moonlight and exploration of the relationships between this, geomagnetic field changes and incidence of violent behavior would help determine whether sensitivity to the light intensity or the magnetic field effects is the critical factor. Comparisons between areas of high and low ambient light would also prove informative. We propose a hypothesis that animals respond to the full moon because of changes in geomagnetic fields, and that the sensitivity of animal magnetoreception increases at this time.
Animals respond to the full moon
Conflict of interest We declare that we have no conflict of interest.
References [1] Bhattacharjee C, Bradley P, Smith M, Scally AJ, Wilson BJ. Do animals bite more during a full moon? Retrospective observational analysis. BMJ 2000;321:1559e61. [2] Thakur CP, Sharma D. Full moon and crime. Br Med J 1984;289: 1789e91. [3] Snoyman P, Holdstock TL. The influence of the sun, moon, climate and economic conditions on crisis incidence. J Clin Psychol 1980;36:884e93. [4] Lieber AL, Sherin CR. Homicides and the lunar cycle: toward a theory of lunar influence on human emotional disturbance. Am J Psychiatry 1972;129:69e74. [5] Lieber AL. Human aggression and the lunar synodic cycle. J Clin Psychiatry 1978;39:385e92. [6] Garzino SJ. Lunar effects on mental behavior e a defense of the empirical-research. Environ Behav 1982;14:395e417. [7] Nakaji S, Parodi S, Fontana V, Umeda T, Suzuki K, Sakamoto J, et al. Seasonal changes in mortality rates from main causes of death in Japan (1970e1999). Eur J Epidemiol 2004;19:905e13. [8] Lieber AL, Agel J. How the moon affects you, Hastings House Pub; 1996. [9] Stolov HL, Cameron AGW. Variations of geomagnetic activity with lunar phase. J Geophys Res 1964;69:4975e82. [10] Ptitsyna NG, Villoresi G, Dorman LI, Iucci N, Tyasto MI. Natural and man-made low-frequency magnetic fields as a potential health hazard. Physics e Uspekhi 1998;41:687e709. [11] Ganjavi O, Schell B, Cachon JC, Porporino F. Geophysical variables and behavior: XXIX. Impact of atmospheric conditions on occurrences of individual violence among Canadian penitentiary populations. Percept Mot Skills 1985;61:259e75. [12] Wiltschko R, Wiltschko W. Magnetoreception. Bioessays 2006; 28:157e68. [13] Walker MM, Diebel CE, Haugh CV, Pankhurst PM, Montgomery JC, Green CR. Structure and function of the vertebrate magnetic sense. Nature 1997;390:371e6.
401 [14] Semm P, Beason RC. Responses to small magnetic variations by the trigeminal system of the bobolink. Brain Res Bull 1990;25: 735e40. [15] Walker MM, Bitterman ME. Honeybees can be trained to respond to very small changes in geomagnetic-field intensity. J Exp Biol 1989;145:489e94. [16] Walcott C. Magnetic orientation in homing pigeons. IEEE Transactions on Magnetics 1980;16:1008e13. [17] Kirschvink J, Dizon AE, Westphal JA. Evidence from strandings for geomagnetic sensitivity in cetaceans. J Exp Biol 1986;120: 1e24. [18] Walker MM, Kirschvink JL, Ahmed G, Dizon AE. Evidence that fin whales respond to the geomagnetic-field during migration. J Exp Biol 1992;171:67e78. [19] Wiltschko W, Wiltschko R. Magnetic orientation and magnetoreception in birds and other animals. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2005;191: 675e93. [20] Kirschvink JL, Kobayashi-kirschvink A, Woodford BJ. Magnetite biomineralization in the human brain. In: Proceedings of the National Academy of Sciences of the United States of America, vol. 89, 1992, pp. 7683e7. [21] Deutschlander ME, Phillips JB, Borland SC. The case for lightdependent magnetic orientation in animals. J Exp Biol 1999; 202:891e908. [22] Henshaw DL, Reiter RJ. Do magnetic fields cause increased risk of childhood leukemia via melatonin disruption? Bioelectromagnetics 2005;7:S86e97. [23] Belov DR, Kanunikov IE, Kiselev BV. Dependence of human EEG spatial synchronization on the geomagnetic activity on the day of experiment. Ross Fiziol Zh Im I M Sechenova 1998;84: 761e74. [24] Deutschlander ME, Borland SC, Phillips JB. Extraocular magnetic compass in newts. Nature 1999;400:324e5. [25] Hu YM, Meng J, Wang YQ, Li CK. Large mesozoic mammals fed on young dinosaurs. Nature 2005;433:149e52. [26] Lohmann KJ, Willows AOD. Lunar-modulated geomagnetic orientation by a marine mollusk. Science 1987;235:331e4. [27] Brown FA, Webb HM, Brett WJ. Magnetic response of an organism and its lunar relationships. Biol Bull 1960;118: 382e92.
available at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/bihy
Why animals respond to the full moon: Magnetic hypothesis Tsutomu Nishimura a,*, Masanori Fukushima b a
Translational Research Center, Graduate School of Medicine, Kyoto University, Shogoin Kawahara-cho 54, Sakyo-ku, Kyoto 606-8507, Japan b Translational Research Informatics Center, 1-5-4 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047, Japan Received 22 April 2009; received in revised form 10 June 2009; accepted 13 June 2009
KEYWORDS Full moon; Animal behavior; Geomagnetic field
Abstract The geomagnetic field is typically about 50 mT (range 20e90 mT). Geomagnetic activity generally decreases by about 4% for the seven days leading up to a full moon, and increases by about 4% after the full moon, lasting for seven days. Animals can clearly detect the changes in magnetic field intensity that occur at full moon, as it has been shown that variations of just a few tens of nT are adequate to form a useful magnetic ‘map’. We think that moonlight increases the sensitivity of animals’ magnetoreception because the radical pair model predicts that magnetoreception is light dependent. In fact, there have been some reports of changes in the sensitivity of magnetoreception with lunar phase. We propose a hypothesis that animals respond to the full moon because of changes in geomagnetic fields, and that the sensitivity of animals’ magnetoreception increases at this time. ª 2009 Elsevier Ltd. All rights reserved.
The effects of phases of the moon on human and animal nature and behavior are well documented. Crime rates, crisis incidence, human aggression, and animal bites to humans are all positively correlated with the phases of the moon [1e6]. In particular, increases in violent behavior in psychiatric settings have been attributed to the full moon [4e6]. Changes in both moonlight and attractive forces occur at full moon. An effect of moonlight intensity would seem the more obvious explanation for changes in animal behavior at this time. However, there is no plausible explanation for
* Corresponding author. Tel.: þ81 75 751 3397; fax: þ81 75 751 3399. E-mail address: [email protected] (T. Nishimura).
why the increased light intensity causes violent behavior, because moonlight (reflected sunlight, particularly longwavelength (yellow and red) light) and diurnal sunlight include similar wavelengths. Also, the incidence of murder is not influenced by seasonality, even in summer when the duration of sunshine is longer [7]. Thus, an alternative theory is needed. Lieber proposed a theory of biological tides, which has two elements: the direct effect of the moon’s gravitational pull on living organisms and indirect effects of the moon mediated by the Earth’s electromagnetic field [8], although detailed data on changes in the Earth’s electromagnetic field were not mentioned in his book. We have researched geomagnetic field changes and changes in animals’ magnetoreception that occur with lunar phases. We propose a hypothesis that animals respond
1756-2392/$ - see front matter ª 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.bihy.2009.06.006
400 to the full moon because of changes in geomagnetic fields and that sensitivity to magnetoreception increases at full moon. The geomagnetic field is typically about 50 mT (range 20e90 mT). Geomagnetic activity generally decreases by about 4% for the seven days leading up to a full moon, and increases by about 4% after the full moon, lasting for seven days [9]. Geomagnetic fields also change during geomagnetic storms. Sudden fluctuations during big geomagnetic storms, due to the superposition of equatorial ring current effects and auroral current effects, can be observed for 1 2 days. These produce field variations as large as 200 300 nT at low latitudes and can exceed 1000 nT at high latitudes [10]. There are some reports that the violence of animals, including humans, increases during the full moon, as described above, and there have also been reports of relationships between human violence and geomagnetic disturbances. For example, a study in Canada showed that geomagnetic disturbances were significantly correlated with minor violence in a psychiatric prison (P Z 0.01), women’s prison (P Z 0.01) and in one medium-security prison (P Z 0.02) [11]. Thus, both the full moon and geomagnetic disturbances are associated with increased violence in humans. Many animals have the ability to detect changes in magnetic field (magnetoreception). In their review of magnetoreception in animals, Wiltschko and Wiltschko presented evidence that animals from a wide range of taxa possess magnetic sense and use magnetic compasses to navigate [12]. Such taxa include mollusks, crustaceans, insects, fish, birds, mammals and amphibians [12]. Animals can clearly detect the changes in magnetic field intensity that occur at full moon, as it has been shown that variations of just a few tens of nT are adequate to form a useful magnetic ‘map’ [13]. Walker and colleagues (1997) reported that thresholds of 10e200 nT have been shown experimentally in some birds [14] and honeybees [15], and inferred for homing pigeons [16] and whales [17,18]. Two hypotheses for magnetoreception are currently discussed: one proposes a chemical compass based on a radical pair mechanism; the other postulates processes involving magnetite particles [19]. Kirschvink and Kobayashi-kirschvink have detected magnetite particles in a variety of tissues from the human brain [20]. The radical pair model predicts that magnetoreception is light dependent, and light is indeed required for magnetic compass orientation in birds and salamanders [19]. In salamanders, light dependent magnetoreception was found to be located in the pineal gland, the ancient ‘third eye’ of vertebrates [21]. In fact, there have been many reports that changes in the electromagnetic field disrupt the nocturnal production of melatonin in the pineal gland of humans [22]. Although, in general, humans cannot feel geomagnetic field changes, the electroencephalogram (EEG) has been shown to respond to geomagnetic field changes [23]. For example, Belov and colleagues found a positive correlation between EEG synchronization parameters and geomagnetic activity [23]. Thus, humans appear to be influenced by the geomagnetic field. We speculate that moonlight increase the sensitivity of animal magnetoreception because the radical pair model
T. Nishimura, M. Fukushima predicts that magnetoreception is light dependent [19]. The first evidence for this came from behavioral experiments with young homing pigeons: birds displaced in total darkness were disoriented, just as young pigeons displaced in a distorted magnetic field are [19]. Disorientation in the absence of visible light was also observed in the salamander Notophthalmus viridescens [19]. Many studies revealed a wavelength dependence of the magnetic compass in amphibians, migratory birds and pigeons [19]. The effects of light on magnetic orientation are different in birds and newts e birds are disorientated at wavelengths longer than 590 nm [24]. Evidence from shoreward-orienting salamanders demonstrates that salamanders perceive a 90 counterclockwise shift in the direction of the magnetic field under long-wavelength (>500 nm) light [21], which corresponds to moonlight (reflected sunlight, particularly longwavelength (yellow and red) light). These differences could be explained by the different lifestyles of birds, which are diurnal, and salamanders, which are nocturnal. Thus, birds do not need to use moonlight whereas salamanders need to use moonlight-dependent magnetoreception when moving around at night. Thus, animals may have developed wavelength-dependent magnetoreception depending on whether they are diurnal or nocturnal. The effect of wavelength on magnetic orientation in mammals is unclear. Mesozoic mammals are commonly portrayed as shrew- or rat-sized animals that were mainly insectivorous, probably nocturnal and lived in the shadow of dinosaurs [25]. Ancestors of mammals were nocturnal. Then, mammal’s magnetoreception may also have responded to moonlight, particularly at the full moon. Moonlight may increase the sensitivity of animal magnetoreception. In fact, there has been one report of changes in the sensitivity of magnetoreception with lunar phase [26]. Lohmann and Willows showed that the marine opisthobranch mollusk Tritonia diomedea aligned itself eastwards, and the rate of steering eastwards was highest at full moon [26]. A similar tendency in directional phenomena has been reported in mud snails [27]. These results support the assumption that the sensitivity of animals’ magnetoreception increases at full moon. It is important to distinguish between the effects of changes in magnetic field strength and moonlight intensity. One way to test our theory that the magnetic field strength is the critical factor would be to investigate the relationship between moon phase and violent behavior, as Lieber and Agel researched [8]. We need to measure geomagnetic changes in cities where there is high ambient light, abolishing an influence of moonlight. If changes in geomagnetic field strength correlate with increases in violent behavior at times other than at full moon, this might suggest an effect of geomagnetic field changes. In addition, measurement of the illumination intensity or spectrum of moonlight and exploration of the relationships between this, geomagnetic field changes and incidence of violent behavior would help determine whether sensitivity to the light intensity or the magnetic field effects is the critical factor. Comparisons between areas of high and low ambient light would also prove informative. We propose a hypothesis that animals respond to the full moon because of changes in geomagnetic fields, and that the sensitivity of animal magnetoreception increases at this time.
Animals respond to the full moon
Conflict of interest We declare that we have no conflict of interest.
References [1] Bhattacharjee C, Bradley P, Smith M, Scally AJ, Wilson BJ. Do animals bite more during a full moon? Retrospective observational analysis. BMJ 2000;321:1559e61. [2] Thakur CP, Sharma D. Full moon and crime. Br Med J 1984;289: 1789e91. [3] Snoyman P, Holdstock TL. The influence of the sun, moon, climate and economic conditions on crisis incidence. J Clin Psychol 1980;36:884e93. [4] Lieber AL, Sherin CR. Homicides and the lunar cycle: toward a theory of lunar influence on human emotional disturbance. Am J Psychiatry 1972;129:69e74. [5] Lieber AL. Human aggression and the lunar synodic cycle. J Clin Psychiatry 1978;39:385e92. [6] Garzino SJ. Lunar effects on mental behavior e a defense of the empirical-research. Environ Behav 1982;14:395e417. [7] Nakaji S, Parodi S, Fontana V, Umeda T, Suzuki K, Sakamoto J, et al. Seasonal changes in mortality rates from main causes of death in Japan (1970e1999). Eur J Epidemiol 2004;19:905e13. [8] Lieber AL, Agel J. How the moon affects you, Hastings House Pub; 1996. [9] Stolov HL, Cameron AGW. Variations of geomagnetic activity with lunar phase. J Geophys Res 1964;69:4975e82. [10] Ptitsyna NG, Villoresi G, Dorman LI, Iucci N, Tyasto MI. Natural and man-made low-frequency magnetic fields as a potential health hazard. Physics e Uspekhi 1998;41:687e709. [11] Ganjavi O, Schell B, Cachon JC, Porporino F. Geophysical variables and behavior: XXIX. Impact of atmospheric conditions on occurrences of individual violence among Canadian penitentiary populations. Percept Mot Skills 1985;61:259e75. [12] Wiltschko R, Wiltschko W. Magnetoreception. Bioessays 2006; 28:157e68. [13] Walker MM, Diebel CE, Haugh CV, Pankhurst PM, Montgomery JC, Green CR. Structure and function of the vertebrate magnetic sense. Nature 1997;390:371e6.
401 [14] Semm P, Beason RC. Responses to small magnetic variations by the trigeminal system of the bobolink. Brain Res Bull 1990;25: 735e40. [15] Walker MM, Bitterman ME. Honeybees can be trained to respond to very small changes in geomagnetic-field intensity. J Exp Biol 1989;145:489e94. [16] Walcott C. Magnetic orientation in homing pigeons. IEEE Transactions on Magnetics 1980;16:1008e13. [17] Kirschvink J, Dizon AE, Westphal JA. Evidence from strandings for geomagnetic sensitivity in cetaceans. J Exp Biol 1986;120: 1e24. [18] Walker MM, Kirschvink JL, Ahmed G, Dizon AE. Evidence that fin whales respond to the geomagnetic-field during migration. J Exp Biol 1992;171:67e78. [19] Wiltschko W, Wiltschko R. Magnetic orientation and magnetoreception in birds and other animals. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2005;191: 675e93. [20] Kirschvink JL, Kobayashi-kirschvink A, Woodford BJ. Magnetite biomineralization in the human brain. In: Proceedings of the National Academy of Sciences of the United States of America, vol. 89, 1992, pp. 7683e7. [21] Deutschlander ME, Phillips JB, Borland SC. The case for lightdependent magnetic orientation in animals. J Exp Biol 1999; 202:891e908. [22] Henshaw DL, Reiter RJ. Do magnetic fields cause increased risk of childhood leukemia via melatonin disruption? Bioelectromagnetics 2005;7:S86e97. [23] Belov DR, Kanunikov IE, Kiselev BV. Dependence of human EEG spatial synchronization on the geomagnetic activity on the day of experiment. Ross Fiziol Zh Im I M Sechenova 1998;84: 761e74. [24] Deutschlander ME, Borland SC, Phillips JB. Extraocular magnetic compass in newts. Nature 1999;400:324e5. [25] Hu YM, Meng J, Wang YQ, Li CK. Large mesozoic mammals fed on young dinosaurs. Nature 2005;433:149e52. [26] Lohmann KJ, Willows AOD. Lunar-modulated geomagnetic orientation by a marine mollusk. Science 1987;235:331e4. [27] Brown FA, Webb HM, Brett WJ. Magnetic response of an organism and its lunar relationships. Biol Bull 1960;118: 382e92.