Author: Bruce A. Carlson
Publisher: Springer Nature
ISBN: 3030291057
Category : Medical
Languages : en
Pages : 378
Book Description
A fundamental goal of neuroscience is to understand how the nervous system extracts biologically relevant information from the natural environment and how it uses that information to guide and coordinate behavior necessary for reproduction and survival. The electrosensory systems of weakly electric teleost fishes and those of nonteleost fishes are attractive systems for addressing basic questions about neuronal information processing and its relationship to natural behavior. Comparative approaches in these fishes have led to the identification of fundamental mechanisms that have shaped the adaptive evolution of sensory systems across animal taxa. Understanding how sensory systems encode and integrate information about the natural world has far reaching implications for advancing our knowledge in the basic biomedical sciences and in understanding how the nervous system has evolved to control behavior. The primary goal of this book is to provide a comparative perspective on the topic of electroreception and review some of the fundamental insights gained from studies of electrosensory and electromotor systems. Although totally independent, this book follows from volume 21 in the Springer Handbook of Auditory Research series, Electroreception (Bullock, T. H., Hopkins, C. D., Popper, A. N., and Fay, R. R., 2005, Springer-Verlag, New York).
Electroreception
Author: Theodore Holmes Bullock
Publisher: Springer Science & Business Media
ISBN: 0387282750
Category : Science
Languages : en
Pages : 479
Book Description
Electroreception has become one of the most revealing areas in the study of the neural basis of behavior, and neurobiologists recognize it as a model sensory system for experimental study. Through studies of electroreception, researchers have gained extensive knowledge about a complete sensory system, from molecular biology to computation, communication, and behavior. The book Electroreception will examine the behavior, structure, and function of the electrosensory systems of fish and other vertebrates. As a comprehensive volume on the subject, the book will serve as both an introduction to the study of electroreception and a reference and review volume for researchers in related fields.
Publisher: Springer Science & Business Media
ISBN: 0387282750
Category : Science
Languages : en
Pages : 479
Book Description
Electroreception has become one of the most revealing areas in the study of the neural basis of behavior, and neurobiologists recognize it as a model sensory system for experimental study. Through studies of electroreception, researchers have gained extensive knowledge about a complete sensory system, from molecular biology to computation, communication, and behavior. The book Electroreception will examine the behavior, structure, and function of the electrosensory systems of fish and other vertebrates. As a comprehensive volume on the subject, the book will serve as both an introduction to the study of electroreception and a reference and review volume for researchers in related fields.
Electroreception: Fundamental Insights from Comparative Approaches
Author: Bruce A. Carlson
Publisher: Springer Nature
ISBN: 3030291057
Category : Medical
Languages : en
Pages : 378
Book Description
A fundamental goal of neuroscience is to understand how the nervous system extracts biologically relevant information from the natural environment and how it uses that information to guide and coordinate behavior necessary for reproduction and survival. The electrosensory systems of weakly electric teleost fishes and those of nonteleost fishes are attractive systems for addressing basic questions about neuronal information processing and its relationship to natural behavior. Comparative approaches in these fishes have led to the identification of fundamental mechanisms that have shaped the adaptive evolution of sensory systems across animal taxa. Understanding how sensory systems encode and integrate information about the natural world has far reaching implications for advancing our knowledge in the basic biomedical sciences and in understanding how the nervous system has evolved to control behavior. The primary goal of this book is to provide a comparative perspective on the topic of electroreception and review some of the fundamental insights gained from studies of electrosensory and electromotor systems. Although totally independent, this book follows from volume 21 in the Springer Handbook of Auditory Research series, Electroreception (Bullock, T. H., Hopkins, C. D., Popper, A. N., and Fay, R. R., 2005, Springer-Verlag, New York).
Publisher: Springer Nature
ISBN: 3030291057
Category : Medical
Languages : en
Pages : 378
Book Description
A fundamental goal of neuroscience is to understand how the nervous system extracts biologically relevant information from the natural environment and how it uses that information to guide and coordinate behavior necessary for reproduction and survival. The electrosensory systems of weakly electric teleost fishes and those of nonteleost fishes are attractive systems for addressing basic questions about neuronal information processing and its relationship to natural behavior. Comparative approaches in these fishes have led to the identification of fundamental mechanisms that have shaped the adaptive evolution of sensory systems across animal taxa. Understanding how sensory systems encode and integrate information about the natural world has far reaching implications for advancing our knowledge in the basic biomedical sciences and in understanding how the nervous system has evolved to control behavior. The primary goal of this book is to provide a comparative perspective on the topic of electroreception and review some of the fundamental insights gained from studies of electrosensory and electromotor systems. Although totally independent, this book follows from volume 21 in the Springer Handbook of Auditory Research series, Electroreception (Bullock, T. H., Hopkins, C. D., Popper, A. N., and Fay, R. R., 2005, Springer-Verlag, New York).
Sensation and Perception
Author: Bennett L. Schwartz
Publisher: SAGE Publications
ISBN: 1506383904
Category : Psychology
Languages : en
Pages : 823
Book Description
The highly accessible Sensation and Perception presents a current and accurate account of modern sensation and perception from both a cognitive and neurocognitive perspective. To show students the relevance of the material to their everyday lives and future careers, authors Bennett L. Schwartz and John H. Krantz connect concepts to real-world applications, such as driving cars, playing sports, and evaluating risk in the military. Interactive Sensation Laboratory Exercises (ISLE) provide simulations of experiments and neurological processes to engage readers with the phenomena covered in the text and give them a deeper understanding of key concepts. The Second Edition includes a revamped version of the In Depth feature from the previous edition in new Exploration sections that invite readers to learn more about exciting developments in the field. Additionally, new Ponder Further sections prompt students to practice their critical thinking skills with chapter topics.
Publisher: SAGE Publications
ISBN: 1506383904
Category : Psychology
Languages : en
Pages : 823
Book Description
The highly accessible Sensation and Perception presents a current and accurate account of modern sensation and perception from both a cognitive and neurocognitive perspective. To show students the relevance of the material to their everyday lives and future careers, authors Bennett L. Schwartz and John H. Krantz connect concepts to real-world applications, such as driving cars, playing sports, and evaluating risk in the military. Interactive Sensation Laboratory Exercises (ISLE) provide simulations of experiments and neurological processes to engage readers with the phenomena covered in the text and give them a deeper understanding of key concepts. The Second Edition includes a revamped version of the In Depth feature from the previous edition in new Exploration sections that invite readers to learn more about exciting developments in the field. Additionally, new Ponder Further sections prompt students to practice their critical thinking skills with chapter topics.
The Neocortex
Author: Barbara L. Finlay
Publisher: Springer Science & Business Media
ISBN: 1489906525
Category : Science
Languages : en
Pages : 256
Book Description
Proceedings of a NATO ARW held in Alagna, Italy, August 26-31, 1989
Publisher: Springer Science & Business Media
ISBN: 1489906525
Category : Science
Languages : en
Pages : 256
Book Description
Proceedings of a NATO ARW held in Alagna, Italy, August 26-31, 1989
The Sensory Modes of Animal Rhetorics
Author: Alex C. Parrish
Publisher: Springer Nature
ISBN: 3030767124
Category : Literary Criticism
Languages : en
Pages : 349
Book Description
The Sensory Modes of Animal Rhetorics: A Hoot in the Light presents the latest research in animal perception and cognition in the context of rhetorical theory. Alex C. Parrish explores the science of animal signaling that shows human and nonhuman animals share similar rhetorical strategies—such as communicating to manipulate or persuade—which suggests the vast impact sensory modalities have on communication in nature. The book demonstrates new ways of seeing humans and how we have separated ourselves from, and subjectified, the animal rhetor. This type of cross-species study allows us to trace the origins of our own persuasive behaviors, providing a deeper and more inclusive history of rhetoric than ever before.
Publisher: Springer Nature
ISBN: 3030767124
Category : Literary Criticism
Languages : en
Pages : 349
Book Description
The Sensory Modes of Animal Rhetorics: A Hoot in the Light presents the latest research in animal perception and cognition in the context of rhetorical theory. Alex C. Parrish explores the science of animal signaling that shows human and nonhuman animals share similar rhetorical strategies—such as communicating to manipulate or persuade—which suggests the vast impact sensory modalities have on communication in nature. The book demonstrates new ways of seeing humans and how we have separated ourselves from, and subjectified, the animal rhetor. This type of cross-species study allows us to trace the origins of our own persuasive behaviors, providing a deeper and more inclusive history of rhetoric than ever before.
The Diversity of Fishes
Author: Douglas E. Facey
Publisher: John Wiley & Sons
ISBN: 1119341833
Category : Science
Languages : en
Pages : 724
Book Description
THE DIVERSITY OF FISHES The third edition of The Diversity of Fishes is a major revision of the widely adopted ichthyology textbook, incorporating the latest advances in the biology of fishes and covering taxonomy, anatomy, physiology, biogeography, ecology, and behavior. Key information on the evolution of various fishes is also presented, providing expansive and conclusive coverage on all key topics pertaining to the field. To aid in reader comprehension, each chapter begins with a summary that provides a broad overview of the content of that chapter, which may be particularly useful for those using the text for a course who don’t intend to address every chapter in detail. Detailed color photographs throughout the book demonstrate just some of the diversity and beauty of fishes that attract many to the field. A companion website provides related videos selected by the authors, instructor resources, and additional references and websites for further reading. Sample topics covered and learning resources included in The Diversity of Fishes are as follows: How molecular genetics has transformed many aspects of ichthyology The close relationship between structure and function, including adaptations to special environments Many physical and behavioral adaptations reflecting the fact that many fishes are both predators and prey Fish interactions with other species within fish assemblages and broader communities, plus their impacts on ecosystems Global maps that more accurately represent the comparative sizes of oceans and land masses than maps used in prior editions For students, instructors, and individuals with an interest in ichthyology, The Diversity of Fishes is an all-in-one introductory resource to the field, presenting vast opportunities for learning, many additional resources to aid in information retention, and helpful recommendations on where to go to explore specific topics further.
Publisher: John Wiley & Sons
ISBN: 1119341833
Category : Science
Languages : en
Pages : 724
Book Description
THE DIVERSITY OF FISHES The third edition of The Diversity of Fishes is a major revision of the widely adopted ichthyology textbook, incorporating the latest advances in the biology of fishes and covering taxonomy, anatomy, physiology, biogeography, ecology, and behavior. Key information on the evolution of various fishes is also presented, providing expansive and conclusive coverage on all key topics pertaining to the field. To aid in reader comprehension, each chapter begins with a summary that provides a broad overview of the content of that chapter, which may be particularly useful for those using the text for a course who don’t intend to address every chapter in detail. Detailed color photographs throughout the book demonstrate just some of the diversity and beauty of fishes that attract many to the field. A companion website provides related videos selected by the authors, instructor resources, and additional references and websites for further reading. Sample topics covered and learning resources included in The Diversity of Fishes are as follows: How molecular genetics has transformed many aspects of ichthyology The close relationship between structure and function, including adaptations to special environments Many physical and behavioral adaptations reflecting the fact that many fishes are both predators and prey Fish interactions with other species within fish assemblages and broader communities, plus their impacts on ecosystems Global maps that more accurately represent the comparative sizes of oceans and land masses than maps used in prior editions For students, instructors, and individuals with an interest in ichthyology, The Diversity of Fishes is an all-in-one introductory resource to the field, presenting vast opportunities for learning, many additional resources to aid in information retention, and helpful recommendations on where to go to explore specific topics further.
Comparative Vertebrate Neuroanatomy
Author: Ann B. Butler
Publisher: John Wiley & Sons
ISBN: 0471733830
Category : Medical
Languages : en
Pages : 739
Book Description
Comparative Vertebrate Neuroanatomy Evolution and Adaptation Second Edition Ann B. Butler and William Hodos The Second Edition of this landmark text presents a broad survey of comparative vertebrate neuroanatomy at the introductory level, representing a unique contribution to the field of evolutionary neurobiology. It has been extensively revised and updated, with substantially improved figures and diagrams that are used generously throughout the text. Through analysis of the variation in brain structure and function between major groups of vertebrates, readers can gain insight into the evolutionary history of the nervous system. The text is divided into three sections: * Introduction to evolution and variation, including a survey of cell structure, embryological development, and anatomical organization of the central nervous system; phylogeny and diversity of brain structures; and an overview of various theories of brain evolution * Systematic, comprehensive survey of comparative neuroanatomy across all major groups of vertebrates * Overview of vertebrate brain evolution, which integrates the complete text, highlights diversity and common themes, broadens perspective by a comparison with brain structure and evolution of invertebrate brains, and considers recent data and theories of the evolutionary origin of the brain in the earliest vertebrates, including a recently proposed model of the origin of the brain in the earliest vertebrates that has received strong support from newly discovered fossil evidence Ample material drawn from the latest research has been integrated into the text and highlighted in special feature boxes, including recent views on homology, cranial nerve organization and evolution, the relatively large and elaborate brains of birds in correlation with their complex cognitive abilities, and the current debate on forebrain evolution across reptiles, birds, and mammals. Comparative Vertebrate Neuroanatomy is geared to upper-level undergraduate and graduate students in neuroanatomy, but anyone interested in the anatomy of the nervous system and how it corresponds to the way that animals function in the world will find this text fascinating.
Publisher: John Wiley & Sons
ISBN: 0471733830
Category : Medical
Languages : en
Pages : 739
Book Description
Comparative Vertebrate Neuroanatomy Evolution and Adaptation Second Edition Ann B. Butler and William Hodos The Second Edition of this landmark text presents a broad survey of comparative vertebrate neuroanatomy at the introductory level, representing a unique contribution to the field of evolutionary neurobiology. It has been extensively revised and updated, with substantially improved figures and diagrams that are used generously throughout the text. Through analysis of the variation in brain structure and function between major groups of vertebrates, readers can gain insight into the evolutionary history of the nervous system. The text is divided into three sections: * Introduction to evolution and variation, including a survey of cell structure, embryological development, and anatomical organization of the central nervous system; phylogeny and diversity of brain structures; and an overview of various theories of brain evolution * Systematic, comprehensive survey of comparative neuroanatomy across all major groups of vertebrates * Overview of vertebrate brain evolution, which integrates the complete text, highlights diversity and common themes, broadens perspective by a comparison with brain structure and evolution of invertebrate brains, and considers recent data and theories of the evolutionary origin of the brain in the earliest vertebrates, including a recently proposed model of the origin of the brain in the earliest vertebrates that has received strong support from newly discovered fossil evidence Ample material drawn from the latest research has been integrated into the text and highlighted in special feature boxes, including recent views on homology, cranial nerve organization and evolution, the relatively large and elaborate brains of birds in correlation with their complex cognitive abilities, and the current debate on forebrain evolution across reptiles, birds, and mammals. Comparative Vertebrate Neuroanatomy is geared to upper-level undergraduate and graduate students in neuroanatomy, but anyone interested in the anatomy of the nervous system and how it corresponds to the way that animals function in the world will find this text fascinating.
Encyclopedia of Animal Behavior
Author:
Publisher: Elsevier
ISBN: 0080453376
Category : Science
Languages : en
Pages : 2662
Book Description
The Encyclopedia of Animal Behavior, Three Volume Set has engaged with great success the efforts of many of the best behavioral biologists of the 21st century. Section editors drawn from the most accomplished behavioral scientists of their generation have enrolled an international cast of highly respected thinkers and writers all of whom have taken great care and joy in illuminating every imaginable corner of animal behavior. This comprehensive work covers not only the usual topics such as communication, learning, sexual selection, navigation, and the history of the field, but also emerging topics in cognition, animal welfare, conservation, and applications of animal behavior. The large section on animal cognition brings together many of the world's experts on the subject to provide a comprehensive overview of this rapidly developing area. Chapters relating to animal welfare give a full view of behavioral interactions of humans with companion animals, farm animals, and animals in the wild. The key role of animal behavior in conservation biology receives broad attention, including chapters on topics such as the effects of noise pollution, captive breeding, and how the behavioral effects of parasites interacts with conservation issues. Animal behavior in environmental biology is highlighted in chapters on the effects of endocrine disruptors on behavior and a large number of chapters on key species, such as wolves, chimpanzees, hyenas and sharks. Clear, accessible writing complements a wealth of information for undergraduate college students about the essential concepts of animal behavior and the application of those concepts across the field. In-depth coverage of concepts, methods, and exemplar organisms serves the needs of graduate students and professionals in the field. From the use of behavior in assessing the welfare of pigs to the social behavior of insects, from animal empathy to bat brains, this authoritative reference, with its in-depth introductory articles, rich array of illustrations, interactive cross-referenced links, and numerous suggested readings, can guide the student or the professional to an expanded appreciation of the far-flung world of animal behavior. An invaluable tool for teaching and a source of enrichment and detail for any topic covered in an animal behavior course, the Encyclopedia of Animal Behavior is the definitive reference work in its field and will be for years to come. Comprehensive work which covers the usual topics along with emerging areas of animal behavior This encyclopedia contains clear, accessible writing and is well illustrated, including an online video, complimenting a wealth of information As an online reference, this work will be subject to period updating. This ensures that the work always remains current Contains in-depth introductions to the material that make each well-illustrated section come alive with the best the new content the discipline has to offer Glossary includes a compendium of behavioral terms that form a succinct mosaic of virtually every concept and phenomenon related to animal behavior Section editors, drawn from around the world, represent the best and the brightest among today's behavioral biologists and have recruited a broad range of internationally recognized experts Editors-in-Chief are experienced scientists and writers who between them have authored or edited eight books and teach courses in animal behavior at their respective universities
Publisher: Elsevier
ISBN: 0080453376
Category : Science
Languages : en
Pages : 2662
Book Description
The Encyclopedia of Animal Behavior, Three Volume Set has engaged with great success the efforts of many of the best behavioral biologists of the 21st century. Section editors drawn from the most accomplished behavioral scientists of their generation have enrolled an international cast of highly respected thinkers and writers all of whom have taken great care and joy in illuminating every imaginable corner of animal behavior. This comprehensive work covers not only the usual topics such as communication, learning, sexual selection, navigation, and the history of the field, but also emerging topics in cognition, animal welfare, conservation, and applications of animal behavior. The large section on animal cognition brings together many of the world's experts on the subject to provide a comprehensive overview of this rapidly developing area. Chapters relating to animal welfare give a full view of behavioral interactions of humans with companion animals, farm animals, and animals in the wild. The key role of animal behavior in conservation biology receives broad attention, including chapters on topics such as the effects of noise pollution, captive breeding, and how the behavioral effects of parasites interacts with conservation issues. Animal behavior in environmental biology is highlighted in chapters on the effects of endocrine disruptors on behavior and a large number of chapters on key species, such as wolves, chimpanzees, hyenas and sharks. Clear, accessible writing complements a wealth of information for undergraduate college students about the essential concepts of animal behavior and the application of those concepts across the field. In-depth coverage of concepts, methods, and exemplar organisms serves the needs of graduate students and professionals in the field. From the use of behavior in assessing the welfare of pigs to the social behavior of insects, from animal empathy to bat brains, this authoritative reference, with its in-depth introductory articles, rich array of illustrations, interactive cross-referenced links, and numerous suggested readings, can guide the student or the professional to an expanded appreciation of the far-flung world of animal behavior. An invaluable tool for teaching and a source of enrichment and detail for any topic covered in an animal behavior course, the Encyclopedia of Animal Behavior is the definitive reference work in its field and will be for years to come. Comprehensive work which covers the usual topics along with emerging areas of animal behavior This encyclopedia contains clear, accessible writing and is well illustrated, including an online video, complimenting a wealth of information As an online reference, this work will be subject to period updating. This ensures that the work always remains current Contains in-depth introductions to the material that make each well-illustrated section come alive with the best the new content the discipline has to offer Glossary includes a compendium of behavioral terms that form a succinct mosaic of virtually every concept and phenomenon related to animal behavior Section editors, drawn from around the world, represent the best and the brightest among today's behavioral biologists and have recruited a broad range of internationally recognized experts Editors-in-Chief are experienced scientists and writers who between them have authored or edited eight books and teach courses in animal behavior at their respective universities
Sensory Biology of Aquatic Animals
Author: Jelle 1987
Publisher: Springer Science & Business Media
ISBN: 1461237149
Category : Science
Languages : en
Pages : 956
Book Description
This volume constitutes a series of invited chapters based on presentations given at an International Conference on the Sensory Biology of Aquatic Animals held June 24-28, 1985 at the Mote Marine Laboratory in Sarasota, Florida. The immediate purpose of the conference was to spark an exchange of ideas, concepts, and techniques among investigators concerned with the different sensory modalities employed by a wide variety of animal species in extracting information from the aquatic environment. By necessity, most investigators of sensory biology are specialists in one sensory system: different stimulus modalities require different methods of stimulus control and, generally, different animal models. Yet, it is clear that all sensory systems have principles in common, such as stimulus filtering by peripheral structures, tuning of receptor cells, signal-to-noise ratios, adaption and disadaptation, and effective dynamic range. Other features, such as hormonal and efferent neural control, circadian reorganization, and receptor recycling are known in some and not in other senses. The conference afforded an increased awareness of new discoveries in other sensory systems that has effectively inspired a fresh look by the various participants at their own area of specialization to see whether or not similar principles apply. This inspiration was found not only in theoretical issues, but equally in techniques and methods of approach. The myopy of sensory specialization was broken in one unexpected way by showing limitations of individual sense organs and their integration within each organism. For instance, studying vision, one generally chooses a visual animal as a model.
Publisher: Springer Science & Business Media
ISBN: 1461237149
Category : Science
Languages : en
Pages : 956
Book Description
This volume constitutes a series of invited chapters based on presentations given at an International Conference on the Sensory Biology of Aquatic Animals held June 24-28, 1985 at the Mote Marine Laboratory in Sarasota, Florida. The immediate purpose of the conference was to spark an exchange of ideas, concepts, and techniques among investigators concerned with the different sensory modalities employed by a wide variety of animal species in extracting information from the aquatic environment. By necessity, most investigators of sensory biology are specialists in one sensory system: different stimulus modalities require different methods of stimulus control and, generally, different animal models. Yet, it is clear that all sensory systems have principles in common, such as stimulus filtering by peripheral structures, tuning of receptor cells, signal-to-noise ratios, adaption and disadaptation, and effective dynamic range. Other features, such as hormonal and efferent neural control, circadian reorganization, and receptor recycling are known in some and not in other senses. The conference afforded an increased awareness of new discoveries in other sensory systems that has effectively inspired a fresh look by the various participants at their own area of specialization to see whether or not similar principles apply. This inspiration was found not only in theoretical issues, but equally in techniques and methods of approach. The myopy of sensory specialization was broken in one unexpected way by showing limitations of individual sense organs and their integration within each organism. For instance, studying vision, one generally chooses a visual animal as a model.
Biology and Physiology of Freshwater Neotropical Fish
Author: Bernardo Baldisserotto
Publisher: Academic Press
ISBN: 0128158735
Category : Science
Languages : en
Pages : 358
Book Description
Biology and Physiology of Freshwater Neotropical Fish is the all-inclusive guide to fish species prevalent in the neotropical realm. It provides the most updated systematics, classification, anatomical, behavioral, genetic, and functioning systems information on freshwater neotropical fish species. This book begins by analyzing the differences in phylogeny, anatomy, and behaviour of neotropical fish. Systems such as cardiovascular, respiratory, renal, digestive, reproductive, muscular, and endocrine are described in detail. This book also looks at the effects of stress on fish immune systems, and how color and pigmentation play into physiology and species differentiation. Biology and Physiology of Freshwater Neotropical Fish is a must-have for fish biologists and zoologists. Students in zoology, ichthyology, and fish farming will also find this book useful for its coverage of some of the world's rarest and least-known fish species. - Features chapters written by top neotropical fish researchers and specialists - Discusses environmental effects on neotropical fishes, including climate change and pollution - Details the phylogenetic occurrence of electroreceptors and electric organs in fish
Publisher: Academic Press
ISBN: 0128158735
Category : Science
Languages : en
Pages : 358
Book Description
Biology and Physiology of Freshwater Neotropical Fish is the all-inclusive guide to fish species prevalent in the neotropical realm. It provides the most updated systematics, classification, anatomical, behavioral, genetic, and functioning systems information on freshwater neotropical fish species. This book begins by analyzing the differences in phylogeny, anatomy, and behaviour of neotropical fish. Systems such as cardiovascular, respiratory, renal, digestive, reproductive, muscular, and endocrine are described in detail. This book also looks at the effects of stress on fish immune systems, and how color and pigmentation play into physiology and species differentiation. Biology and Physiology of Freshwater Neotropical Fish is a must-have for fish biologists and zoologists. Students in zoology, ichthyology, and fish farming will also find this book useful for its coverage of some of the world's rarest and least-known fish species. - Features chapters written by top neotropical fish researchers and specialists - Discusses environmental effects on neotropical fishes, including climate change and pollution - Details the phylogenetic occurrence of electroreceptors and electric organs in fish