Main description:

Biological effects of magnetic fields have been studied in many animals and plants. The magnetic fields were of a wide intensity range and, as alternating fields, of a wide frequency range and of a variety of impulse shapes. Effects on the cellular level, on bio chemical processes, growth and development, interactions with physiology, sensory input, reflexes and rhythm control, to name just a few, have been reported. Numerous magnetically induced changes in behavior have also been described. Recently, the amount of literature covering biological effects of magnetic fields has been rapidly increasing. By now it has grown to such an extent that it can no longer be covered in one volume. Most reviews specialize and focus on particular aspects and/or types of fields or effects. For example, the book edited by MARET et al. (1986) gives an overview on biological effects of steady magnetic fields, MISAKIAN et al. (1993) reviewed those of extremely low frequency magnetic fields, focusing on in vitro effects. BERN HARD (1992) reported on 'electromagnetic smog' in view of pos sible effects on human health and well-being, and a series of papers edited by AMEMIYA (1994) summarizes Japanese research on effects of electromagnetic fields ranging from extern ely low to ultra-high frequencies. TENFORDE (1979) and ADEY (1981) sum marized and discussed tissue interactions, REITER (1993a) neu roendocrine and neurochemical changes associated with various kinds of electromagnetic fields. The book edited by KIRSCHVINK et al.

Contents:

1 Background.- 1 Magnetic Fields.- 1.1 The Magnetic Field of the Earth.- 1.1.1 The Vector Field.- 1.1.2 Spatial Distribution of the Geomagnetic Field.- 1.1.2.1 Worldwide Gradients and the Non-dipole Field.- 1.1.2.2 Magnetic Topography and Anomalies.- 1.1.3 Temporal Variations of the Magnetic Field.- 1.1.3.1 Short-Term Variation.- 1.1.3.2 Long-Term Variation.- 1.1.4 Man-Made Magnetic Noise.- 1.2 Magnetic Manipulations.- 1.2.1 Altering Magnetic Conditions.- 1.2.1.1 Magnets and Shielding.- 1.2.1.2 Coil Systems.- 1.2.2 Describing Magnetic Fields.- 1.2.2.1 Measuring Direction and Intensity.- 1.2.2.2 Carthesian and Polar Coordinates.- 1.2.3 Treatments Designed to Affect Magnetic Receptors.- 1.3 Summary.- 2 Orientation.- 2.1 Passive Responses Versus Active Behavior.- 2.1.1 Magnetotactic Bacteria.- 2.1.2 Orientation in Animals.- 2.2 Various Uses of Magnetic Information.- 2.2.1 Orientation Via an External Reference.- 2.2.2 The Role of Magnetic Cues.- 2.2.3 Demonstrating Compass Orientation.- 2.3 Analysis of Orientation Data.- 2.4 Summary.- 2 Directional Orientation.- 3 Magnetotaxis and Alignment Behaviors.- 3.1 Magnetotactic Orientation.- 3.2 Early Reports on Alignments in Insects.- 3.2.1 Alignments in Termites.- 3.2.2 Aligned Resting Positions of Diptera.- 3.2.3 Magnetic Alignments in Other Insects.- 3.3 Alignment Behaviors in Honeybees.- 3.3.1 Resting Positions.- 3.3.2 Prominent Directions of the Waggle Dance.- 3.3.2.1 Zero Crossings of 'Misdirection'.- 3.3.2.2 Dancing on a Horizontal Comb.- 3.4 Alignment Behavior in Vertebrates.- 3.5 Biological Significance.- 3.6 Summary.- 4 Compass Orientation.- 4.1 The Magnetic Compass of Birds.- 4.1.1 Demonstrating Magnetic Orientation in Caged Migrants.- 4.1.2 Functional Characteristics.- 4.1.2.1 Functional Range.- 4.1.2.2 'Inclination Compass'.- 4.1.2.3 Constant Magnetic Intensity Required.- 4.1.2.4 Accuracy.- 4.1.3 The Magnetic Compass in Migratory Orientation.- 4.1.3.1 A Widespread Mechanism Among Migrants.- 4.1.3.2 Transequatorial Migrants.- 4.1.3.3 Innate Information on the Migratory Direction.- 4.1.4 Magnetic Compass Orientation in Homing.- 4.1.4.1 Locating the Home Course.- 4.1.4.2 A Reference for Route Reversal.- 4.2 Magnetic Compass Orientation in Other Vertebrates.- 4.2.1 Fishes.- 4.2.1.1 Eels (Anguillidae).- 4.2.1.2 Salmons (Salmonidae).- 4.2.1.3 Elasmobranchs.- 4.2.2 Amphibians.- 4.2.2.1 Salamanders and Newts (Urodela).- 4.2.2.2 Toads (Anura: Bufonidae).- 4.2.3 Reptiles.- 4.2.3.1 Box Turtles (Testudines: Emydae).- 4.2.3.2 Marine Turtles.- 4.2.4 Mammals.- 4.2.4.1 Rodents (Rodentia).- 4.2.4.2 Horses (Perissodactyla: Equidae).- 4.2.4.3 Man (Primates: Hominidae).- 4.2.4.4 The Technical Compass.- 4.3 Magnetic Compass Orientation in Invertebrates.- 4.3.1 Mollusks.- 4.3.2 Crustaceans.- 4.3.2.1 Lobsters (Decapoda: Palinuridae).- 4.3.2.2 Sandhoppers (Amphipoda: Talitridae).- 4.3.2.3 Isopods (Isopoda).- 4.3.3 Insects.- 4.3.3.1 Termites (Isoptera).- 4.3.3.2 Ants, Wasps, and Bees (Hymenoptera).- 4.3.3.3 Beetles (Coleoptera).- 4.3.3.4 Flies (Diptera).- 4.3.3.5 Butterflies and Moths (Lepidoptera).- 4.4 The Use of the Magnetic Field for Direction Finding.- 4.4.1 Different Types of Mechanisms.- 4.4.2 Biological Significance of Magnetic Compass Use.- 4.4.2.1 Courses of Various Origin in Different Behaviors.- 4.4.2.2 One Compass for All Tasks?.- 4.5 Summary.- 5 The Magnetic Compass as Component of a Multifactorial System.- 5.1 Orientation Based on Various Factors of Different Nature.- 5.1.1 Different Types of Orientation Cues.- 5.1.2 Celestial Compass Mechanisms.- 5.2 Homing and Migration of Birds.- 5.2.1 Interaction of Orientation Mechanisms in Homing.- 5.2.1.1 Interaction of Sun Compass and Magnetic Compas.- 5.2.1.2 Mechanisms Determining the Home Course.- 5.2.1.3 A Model for Homing.- 5.2.2 Interaction of Various Cues in Migratory Orientation.- 5.2.2.1 Realization of the Starting Course.- 5.2.2.2 Interactions During Migration.- 5.2.2.3 An Integrated System for Nocturnal Migration.- 5.2.2.4 Day Migrants.- 5.2.2.5 Changes in Migratory Direction.- 5.2.3 Maintaining Directions - Staying on Course.- 5.2.3.1 Free-Flying Birds.- 5.2.3.2 Cage Experiments.- 5.2.3.3 Visual Help to Stay on Course.- 5.3 Migrations and Homing of Fishes and Amphibians.- 5.3.1 Orientation of Atlantic Eels (Gen. Anguilla).- 5.3.1.1 The Life Cycle of Eels.- 5.3.1.2 Preprogrammed Migration.- 5.3.2 Orientation of Salmons (Salmonidae).- 5.3.2.1 Migration to the Nursery Lake.- 5.3.2.2 Seaward Migration.- 5.3.2.3 The Time at Sea and the Return to the Home Estuary.- 5.3.2.4 Return to the Home Stream.- 5.3.2.5 Population-Specific Migration Programs.- 5.3.3 Homing of Toads (Gen. Bufo).- 5.3.3.1 Cues Used in Homing to the Breeding Pond.- 5.3.3.2 Differences Between Species.- 5.4 Orientation at the Borderline Land-Sea.- 5.4.1 Orientation Factors Involved.- 5.4.1.1 Compass Orientation.- 5.4.1.2 The Origin of Landward and Seaward Tendencies.- 5.4.1.3 A Multifactorial System.- 5.4.2 Relative Significance of Various Factors.- 5.5 The Role of the Magnetic Compass Compared to That of Other Cues.- 5.5.1 Control of the Direction of Movement.- 5.5.1.1 Compass Orientation Versus Local Cues.- 5.5.1.2 Magnetic Compass Versus Celestial Compass Mechanisms.- 5.5.1.3 Maintaining a Course.- 5.5.2 The Magnetic Field as a Directional Reference.- 5.5.2.1 Genetically Encoded Courses.- 5.5.2.2 Acquired Courses and Learning Processes.- 5.6 Summary.- 3 Non-Compass Responses.- 6 Non-Compass Orientation by the Magnetic Field.- 6.1 Magnetic Components in Navigational 'Maps'.- 6.1.1 Magnetic Parameters in the 'Map' of Homing Pigeons.- 6.1.1.1 Behavior at Magnetic Anomalies.- 6.1.1.2 Effects Associated with Temporal Changes in the Magnetic Field.- 6.1.1.3 Experimental Manipulations.- 6.1.2 An Assessment of the Role of Magnetic Factors in the Avian 'Map'.- 6.1.2.1 Variability.- 6.1.2.2 Effects on Homing.- 6.1.2.3 Open Questions about 'Map' Effects.- 6.1.2.4 Significance of Magnetic 'Map' Effects.- 6.1.3 Magnetic 'Map' Factors in the Orientation of Other Vertebrates.- 6.2 Orientation Along the Magnetic Relief.- 6.2.1 The Migration of Cetaceans.- 6.2.1.1 Evidence from Strandings and Sightings.- 6.2.1.2 Following the Relief as Navigational Strategy.- 6.2.2 Orientation of Sharks Near Seamounts.- 6.2.3 The Relief Hypothesis: Problems and Open Questions.- 6.3 Magnetic Parameters Controlling the Routes of Extended Migrations.- 6.3.1 Magnetic Conditions Acting as Triggers During Bird Migration.- 6.3.2 Control of Oceanic Migration in Young Sea Turtles.- 6.3.3 Immediate Control of the Migration Route.- 6.4 Theoretical Considerations.- 6.4.1 What Factors Are Used?.- 6.4.2 Variability and the Detection of Minute Differences.- 6.4.2.1 Spatial Variability.- 6.4.2.2 Temporal Variations.- 6.4.3 Hypotheses with Open Questions.- 6.5 Summary.- 7 Other Non-Compass Effects Associated with Magnetic Fields.- 7.1 Effects Associated with Temporal Variations of the Geomagnetic Field.- 7.1.1 'Misdirection' in the Waggle Dance of Honeybees.- 7.1.1.1 Curves of 'Misdirection' Recorded in the Geomagnetic Field.- 7.1.1.2 'Misdirection' in Magnetic Fields of Various Intensities.- 7.1.1.3 Problems and Open Questions.- 7.1.1.4 Other Phenomena Associated with the Waggle Dance.- 7.1.2 Interference with Biological Rhythms.- 7.1.2.1 Breakdown of Rhythmicity Caused by Magnetic Manipulations.- 7.1.2.2 Rhythmicity Based on Periodic Changes in Magnetic Intensity.- 7.1.2.3 Magnetic Variations as Zeitgeber?.- 7.1.3 Effects of K-Variation and Magnetic Storms.- 7.2 Effects of Transmitters, Radar Stations, etc. on Bird Orientation.- 7.2.1 Migrating Birds.- 7.2.2 Homing Pigeons.- 7.3 Responses to Experimentally Induced Magnetic Changes.- 7.3.1 Invertebrates.- 7.3.2 Vertebrates.- 7.4 Summary.- 4 Perception of Magnetic Fields.- 8 Conditioning Experiments.- 8.1 Cardiac Conditioning.- 8.2 Operant Conditioning.- 8.2.1 Directional Training.- 8.2.2 Discrimination of Two Alternatives.- 8.2.2.1 Arthropods.- 8.2.2.2 Vertebrates.- 8.3 Principal Differences Between Magnetic and Other Stimuli.- 8.3.1 Orientation Mechanisms in Training Experiments.- 8.3.2 Constraints of Learning.- 8.3.3 A Factor Containing Directional Information.- 8.4 Summary.- 9 Obtaining Magnetic Information.- 9.1 Perception Based on Induction.- 9.1.1 Voltage Gradients Perceived by Electroreceptors.- 9.1.2 Electrophysiological Recordings from the Lateralis System.- 9.1.3 A Special Mechanism of Some Marine Vertebrates.- 9.2 Perception Via Photopigments.- 9.2.1 Excited Triplet State Macromolecules as Transducers.- 9.2.1.1 The Resonance Model.- 9.2.1.2 A 'Chemical Compass' Based on Biradicals.- 9.2.2 Electrophysiological Recordings from the Visual System.- 9.2.3 Behavioral Tests for Light-Dependent Orientation Responses.- 9.2.3.1 Orientation in the Absence of Light.- 9.2.3.2 Orientation Under Light of Various Wavelengths.- 9.2.3.3 Two Patterns of Responses.- 9.2.4 Compass Information from the Retina?.- 9.3 Perception Based on Ferromagnetic Particles.- 9.3.1 Magnetite Particles as Transducers.- 9.3.1.1 The Magnetic Properties of Magnetite Particles.- 9.3.1.2 Magnetic Material Is Widespread Among Animals.- 9.3.1.3 Search for Magnetite in Insects.- 9.3.1.4 Magnetite Found in the Head of Vertebrates.- 9.3.1.5 Receptors.- 9.3.2 Electrophysiological Recordings.- 9.3.2.1 Recordings from the Ophthalmic Nerve in Vertebrates.- 9.3.2.2 Recordings from Honeybees.- 9.3.3 Treatments Designed to Affect Magnetite-based Receptors.- 9.3.3.1 Honeybees.- 9.3.3.2 Homing Birds.- 9.3.3.3 Migrating Birds.- 9.3.3.4 The Interpretation of Behavioral Findings.- 9.3.4 Receptors Based on Magnetite Particles.- 9.3.4.1 Is the 'Map' Involved?.- 9.3.4.2 Single Domains or Superparamagnetic Particles?.- 9.3.4.3 Open Questions.- 9.4 Magnetoreception in the Light of the Available Evidence.- 9.4.1 Open Questions About Transducers.- 9.4.2 Evolutionary Considerations.- 9.5 Other Electrophysiological Responses to Magnetic Stimuli.- 9.5.1. Recordings from Vertebrates.- 9.5.2 Recordings from Invertebrates.- 9.6 Summary.- 5 Outlook.- 10 Research on Magnetic Phenomena in Biology.- 10.1 Slow Acceptance of Magnetic Orientation.- 10.2 Present and Future Research.- 10.2.1 Bioelectromagnetic Research.- 10.2.2 Magnetoreception and Magnetic Orientation.- References.- Taxonomic Index of Animal Species.