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Birds are able to perform numerous tasks with a high degree of complexity. It is not apparent that the structures associated with the cognitive ability of the bird brain are comparable to those of their mammalian counterparts. As with other parts of the body, the brains of distantly related species tend to be derived from the same basic elements found in the common ancestor; they exhibit homology. So although the common ancestor of birds and mammals lived approximately 300 million years ago, studies of extant reptiles have revealed that the reptilian (therapsid and sauropsid) forebrain is cortical-like in origin and therefore the common ancestor should also have shared this trait. If so, the forebrain of modern birds and mammals is expected to be cortical-like as well. This seems to be the case. This chapter focuses on the neural specializations found in birds, notably those important in foraging, long-distance navigation, and song production.

This chapter focuses on magnetoreception in animals. It provides a brief overview of the physics of the Earth's magnetic fields, followed by a description of animals known to sense these fields. Magnetic sense is present in many invertebrates such as bees, mealworm beetles, termites, lobsters, and marine mollusk. Migratory vertebrates that respond to magnetic fields include elasmobranchs, salmon, trout, eels, and tuna. Amphibians, birds, and mammals such as the blind mole rat use magnetic cues for navigation. The chapter also identifies sea turtles and cetaceans as the only secondarily aquatic tetrapods that have magnetic sense.

The question of how animals find their way during migration, which orientation cues they use, and how they can perceive the information and transfer it to a migratory direction has fascinated humans for a long time. During the past decade, the field of animal orientation and navigation has seen significant advances in the understanding of the molecular and physiological mechanisms of different compass systems used by animals for orientation and navigation. Most notable are the progresses made in the understanding of how animals can sense information from the Earth’s magnetic field. In this chapter, current knowledge on the sensory modalities used by animals for orientation and navigation are reviewed, challenges are outlined, and future approaches are suggested and discussed.

Touch and taste provide information about objects in contact with, and inside, the body for use in detection and manipulation of food items. Four main types of touch receptors are found distributed in most parts of the body but some birds have ‘bill tip organs’ with very high concentrations of touch receptors. Three main types of bill tip organs are found in waterfowl, parrots, shorebirds, ibises, and kiwi. They allow birds to locate hidden objects with the bill alone and parrots to use their bills as third limbs. Seven types of taste receptors exist in birds, mainly in the mouth cavity but also within the gut. Information from these receptors play key roles in food intake and aids shorebirds in detecting profitable feeding locations. Detection of the geomagnetic field, by means of two known mechanisms, is probably widespread among birds. It plays a key role in direction and position finding.

This chapter provides a comprehensive introduction to magnetic materials in medicine and biology with emphasis on nanoscale magnetic particles tailored for imaging, diagnostics, and therapy. Topics covered include magnetic resonance imaging (MRI), magnetic particle imaging (MPI), high gradient magnetic separation, diagnostics using both “on-chip” detection with magnetoresistive sensors and magnetorelaxometry, magnetic fluid hyperthermia, and targeted delivery of drugs and genes (magnetofection). In addition, methods of nanoparticle synthesis, including control of their size, size distribution, shape, surface charge and functionalization, optimization of their magnetic characteristics for each specific application, combined with a discussion of their in vivo biodistribution, paticokinetics and eventual clearance, is presented. We conclude with a discussion of magnetoreception in animals; an exciting area of work in neurobiology aimed at understanding mechanisms of sensing the Earth’s weak geomagnetic field (~30μTμ0−1).

Macroscopic and microscopic theories of magnetic polarization are discussed. The origin of domains, domain walls, and of the hysteresis curve and the contrast between soft and hard magnetic materials are explained. The more important elements of the quantum theory of magnetism are discussed. The principles of the alignments in antiferromagnetic and ferromagnetic materials are explained. Magnetic resonance phenomena are discussed. Magnetoresistance and spintronics and their device prospects are also discussed at some length.