A live-bearing mode of reproduction implies morphological and physiological constraints, which in fish might be influenced by the physical characteristics of water: a higher density which favours hydrodynamic body shapes and requires an extensive muscle system to propel the bodies through the dense liquid. This thesis aims to improve the understanding of the relationship between the morphological changes caused by pregnancy and the swimming performance of fish. I based my research on the live-bearing fish family Poeciliidae, which presents a wide variation of maternal provisioning that range from feeding their internally developing embryos exclusively from the nutrients that have been stored in the egg-yolk prior to fertilization (lecithotrophy), to almost exclusively nourish them through a placenta (placentotrophy).

Among the fishes, a remarkably wide range of biological adaptations to diverse habitats has evolved. As well as living in the conventional habitats of lakes, ponds, rivers, rock pools and the open sea, fish have solved the problems of life in deserts, in the deep sea, in the cold antarctic, and in warm waters of high alkalinity or of low oxygen. Along with these adaptations, we find the most impressive specializations of morphology, physiology and behaviour. For example we can marvel at the high-speed swimming of the marlins, sailfish and warm-blooded tunas, air-breathing in catfish and lung fish, parental care in the mouth-brooding cichlids and viviparity in many sharks and toothcarps. Moreover, fish are of considerable importance to the survival of the human species in the form of nutritious, delicious and diverse food. Rational exploitation and management of our global stocks of fishes must rely upon a detailed and precise insight of their biology. The Chapman & Hall Fish and Fisheries Series aims to present timely volumes reviewing important aspects of fish biology. Most volumes will be of interest to research workers in biology, zoology, ecology and physiology but an additional aim is for the books to be accessible to a wide spectrum of non-specialist readers ranging from undergraduates and postgraduates to those with an intrerest in industrial and commercial aspects of fish and fisheries.

Fish have evolved a great variety of swimming modes and morphologies. Theory suggests that the morphology of median and paired fin swimmers like knifefish specializes them for maneuvering while inhibiting their performance in sustained and acceleratory swimming. However, this idea has not been explicitly tested and the link between shape and swimming mode in this group is poorly understood. This study compares morphological measurements of 116 species (51 knifefish) across four orders to investigate the diversity of shape in knifefish and closely related species. Sprint speeds, escape responses, and cost of transport were measured in 7 species (5 knifefish) to understand the physiological performance of these fish. Results indicated morphological constraints and unexpectedly high swimming performance associated with gymnotiform locomotion. Together, these data test common hypotheses in the field of fish swimming and provide a clearer picture of the evolution of diversity in fish locomotion.

Swimming is an integral part of the life history of many fish species as is intimately linked with their ability to express feeding and predator avoidance behaviors, habitat selection and environmental preferences, social and reproductive behaviors as well as migratory behaviors. Therefore, swimming is an important determinant factor of fitness in a true Darwinian sense and, not surprisingly, swimming performance has been often used as a measure of physiological fitness in fish. The main aim of this Research Topic is to showcase some of the current studies designed to improve our understanding of the physiological energetic and metabolic requirements of swimming and of the adaptive responses to swimming in fish.

Fish form an extremely diverse group of vertebrates. At a conservative estimate at least 40% of the world's vertebrates are fish. On the one hand they are united by their adaptations to an aquatic environment and on the other they show a variety of adaptations to differing environmental conditions - often to extremes of temperature, salinity, oxygen level and water chemistry. They exhibit an array of behavioural and reproductive systems. Interesting in their own right, this suite of adaptive physiologies provides many model systems for both comparative vertebrate and human physiologists. This four volume encyclopedia covers the diversity of fish physiology in over 300 articles and provides entry level information for students and summary overviews for researchers alike. Broadly organised into four themes, articles cover Functional, Thematic, and Phylogenetic Physiology, and Fish Genomics. Functional articles address the traditional aspects of fish physiology that are common to all areas of vertebrate physiology including: Reproduction, Respiration, Neural (Sensory, Central, Effector), Endocrinology, Renal, Cardiovascular, Acid-base Balance, Osmoregulation, Ionoregulation, Digestion, Metabolism, Locomotion, and so on. Thematic Physiology articles are carefully selected and fewer in number. They provide a level of integration that goes beyond the coverage in the Functional Physiology topics and include discussions of Toxicology, Air-breathing, Migrations, Temperature, Endothermy, etc. Phylogenetic Physiology articles bring together information that bridges the physiology of certain groupings of fishes where the knowledge base has a sufficient depth and breadth and include articles on Ancient Fishes, Tunas, Sharks, etc. Genomics articles describe the underlying genetic component of fish physiology and high light their suitability and use as model organisms for the study of disease, stress and physiological adaptations and reactions to external conditions. Winner of a 2011 PROSE Award Honorable Mention for Multivolume Science Reference from the Association of American Publishers The definitive encyclopedia for the field of fish physiology Three volumes which comprehensively cover the entire field in over 300 entries written by experts Detailed coverage of basic functional physiology of fishes, physiological themes in fish biology and comparative physiology amongst taxonomic Groups Describes the genomic bases of fish physiology and biology and the use of fish as model organisms in human physiological research Includes a glossary of terms

Among the fishes. a remarkably wide range ofbiological adaptations to diverse habitats has evolved. As weIl as living in the conventional habitats of lakes. ponds. rivers. rock pools and the open sea. fish have solved the problems of life in deserts. in the deep sea. in the cold Antarctic. and in warm waters of high alkalinity or of low oxygen. Along with these adaptations. we find the most impressive specializations of morphology. physiology and behaviour. For example we can marvel at the high-speed swimming of the marlins. sailfish and warm-blooded tunas. air breathing in catfish and lungfish. parental care in the mouth-brooding cichlids and viviparity in many sharks and toothcarps. Moreover. fish are of considerable importance of the survival of the human species in the form ofnutritious and delicious food ofnumerous kinds. Rational exploitation and management of our global stocks of fishes must rely upon a detailed and precise insight of their biology. The Chapman and Hall Fish and Fisheries Series aims to present timely volumes reviewing important aspects of fish biology. Most volumes will be of interest to research workers in biology. zoology. ecology and physiology. but an additional aim is for the books to be accessible to a wide spectrum of non specialist readers ranging from undergraduates and postgraduates to those with an interest in industrial and commercial aspects of fish and fisheries.

Traditionally, behaviour and physiology have been considered two separate fields of biology with the majority of available literature focusing on one or the other. Recently the need for a multidisciplinary approach to these topics has been realised, highlighted by some of the sessions to be held at the 2003 annual meeting of the Society for Integrative and Comparative Biology such as 'regulation of behaviour' and 'mechanisms of behaviour'. The proposed volume aims to bring together these disciplines in a comprehensive review of the available literature. Fish Physiology: Behaviour and Physiology of Fish will be novel in actively bridging these two areas of fish biology together and considering them as inextricably linked. The progression of chapters focuses on different aspects of the life history of a fish, from predator avoidance through to reproduction, each written by scientists currently bridging the gap between behaviour and physiology in their own specialised subdiscipline. Multidisciplinary and integrative research in fish biology Written by internationally recognized researchers Encompasses the whole life span of fish A wide variety of inter-related topics presented in a cohesive format

Fish accomplish most of their basic behaviors by swimming. Swimming is fundamental in a vast majority of fish species for avoiding predation, feeding, finding food, mating, migrating and finding optimal physical environments. Fish exhibit a wide variety of swimming patterns and behaviors. This treatise looks at fish swimming from the behavioral and