The Physiology of Fishes

By

Blli Hammond

Preface

Fish physiology is the scientific study of how the component parts of fish function together in the living fish. It can be contrasted with fish anatomy, which is the study of the form or morphology of fishes. In practices, fish anatomy and physiology complement each other, the former dealing with the structure of a fish, its organs or component parts and how they are put together, such as might be observed on the dissecting table or under the microscope, and the later dealing with how those components function together in the living fish.

Fishery science is the outcome of the intensive efforts made by the author for more than five consecutive years to bring the universally spread documented information’s and data. Both traditional as well as research oriented recent findings, before the scientific world in a consolidated from, specially before those who are concerned with fish farming and for capture of fishes from varied water sources. Fisheries science is a branch of marine science that deals with studies on the life history and state of fish stock. The term 'state of a fish stock' refers to the number and weight of fish in the stock (i. e.  Current stock biomass in tonnes).

Most physical adaptations in fish occur in the mouth, body shape, coloration or method of reproduction.  Various adaptations in these areas help fish survive in their habitats. Fish that forage on insects in streams have a much different mouth structure than fish that feed on other fish. The walleye, for example, has large jaws strong teeth to help it catch its food. Some fish have no teeth, only round vacuum-like mouth, these fish suck up organic material from the bottom or a stream or river.

The circulatory system serves to move blood to a site or sites where it can be oxygenated, and where wasters can be disposed. Circulation then serves to bring newly oxygenated blood to the tissues of the body. As oxygen and other chemicals diffuse out of the blood cells and into the fluid surrounding the cells of the body's tissues, waste produces diffuse into the blood cells to be carried away. Blood circulates through organs such as the liver and kidneys where wastes were removed, and back to the lungs for a fresh dose of oxygen. And then process repeats itself. This process of circulation is necessary for continued life of the cells, tissues and even of the whole organisms. Before we talk about the heart, we should give a brief background of the two broad types of circulation found in animals.

Being vertebrates, fish have a vertebral column - the backbone - and a cranium covering the brain. The backbone runs from the head to the tail fin and is composed of segments (vertebrae). These vertebrae are extended dorsally to form neural spines, and in the trunk region they have lateral processes that bear ribs. The ribs are cartilaginous or bony structures in the connective tissue (myocommata) between the muscle segments (myotomes). Usually, there is also a corresponding number of false ribs or "pin bones" extending more or less horizontally into the muscle tissue. These bones cause a great deal of trouble when fish are being filleted or otherwise prepared for food.
             The cardiovascular system is of considerable interest to the fish technologist since it is important in some species to bleed the fish (i.e., remove most of the blood) after capture. The fish heart is constructed for single circulation. In bony fish it consists of two consecutive chambers pumping venous blood towards the gills via the ventral aorta. After being aerated in the gills, the arterial blood is collected in the dorsal aorta running just beneath the vertebral column and from here it is dispersed into the different tissues via the capillaries.
             The venous blood returns to the heart, flowing in veins of increasingly larger size (the biggest is the dorsal vein which is also located beneath the vertebral column). The veins all gather into one blood vessel before entering the heart. The total volume of the blood in fish ranges from 1.5 to 3.0 per cent of the body weight. Most of it is located in the internal organs while the muscular tissues, constituting two-thirds of the body weight, contain only 20 per cent of the blood volume. This distribution is not changed during exercise since the light muscle in particular is not very vascularized.

The Physiology of Fishes provides comprehensive coverage of the most important aspects of the most important aspects of the form and function of fishes.

Contents

Chapter 1: Fish Physiology

Chapter 2: Circulatory System in Fish

Chapter 3: Anatomy and Physiology of Fishes

Chapter 4: Endocrine Glands

Chapter 5: Digestion in Fishes

Chapter 6: Metabolism in Fish

Chapter 7: Gas Exchange and Physiology Adaptation

Chapter 8: Fish Anatomy and Reproductive System

Chapter 9: Development of Fish Embryology

Chapter 10: Fisheries and Aquaculture Behaviour

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 Prep. / Ayman Ashry

Manage. / Mona Mahmoud