Fishes have been especially important in the study of animal behaviour, where research on fishes has provided a broad base for the understanding of the more flexible behaviour of the higher vertebrates. For example, the readiness of many fishes to acclimate to captivity has allowed biologists to study behaviour, physiology, and even ecology under relatively natural conditions. As predators on mosquito larvae, they help curb malaria and other mosquito-borne diseases.įishes are valuable laboratory animals in many aspects of medical and biological research. (For a detailed discussion of the technology and economics of fisheries, see commercial fishing.) Another practical reason for studying fishes is their use in disease control. Overfishing, pollution, and alteration of the environment are the chief enemies of proper fisheries management, both in fresh waters and in the ocean. This resource, once thought unlimited, is now realized to be finite and in delicate balance with the biological, chemical, and physical factors of the aquatic environment. A more obvious reason for interest in fishes is their role as a moderate but important part of the world’s food supply. Fishes are of interest to humans for many reasons, the most important being their relationship with and dependence on the environment. The study of fishes, the science of ichthyology, is of broad importance. Bony fishes also have an operculum that covers the gill slits. Unlike the scales of the cartilaginous fishes, those of bony fishes, when present, grow throughout life and are made up of thin overlapping plates of bone.
Examples range from the tiny seahorse to the 450-kg (1,000-pound) blue marlin, from the flattened soles and flounders to the boxy puffers and ocean sunfishes. The bony fishes are by far the largest class. Sharks, skates, and rays are examples of cartilaginous fishes. Modern fish of this class lack a swim bladder, and their scales and teeth are made up of the same placoid material. As the name implies, the skeletons of fishes of the class Chondrichthyes (from chondr, “cartilage,” and ichthyes, “fish”) are made entirely of cartilage. Extant agnathans are the lampreys and the hagfishes. For example, the jawless fishes (Agnatha) have gills in pouches and lack limb girdles. Living fishes represent some five classes, which are as distinct from one another as are the four classes of familiar air-breathing animals- amphibians, reptiles, birds, and mammals. These features are gill slits at some point in the life cycle, a notochord, or skeletal supporting rod, a dorsal hollow nerve cord, and a tail. As members of the phylum Chordata, fish share certain features with other vertebrates. It describes a life-form rather than a taxonomic group. The term fish is applied to a variety of vertebrates of several evolutionary lines. SpaceNext50 Britannica presents SpaceNext50, From the race to the Moon to space stewardship, we explore a wide range of subjects that feed our curiosity about space!.Learn about the major environmental problems facing our planet and what can be done about them! Saving Earth Britannica Presents Earth’s To-Do List for the 21st Century.Britannica Beyond We’ve created a new place where questions are at the center of learning.100 Women Britannica celebrates the centennial of the Nineteenth Amendment, highlighting suffragists and history-making politicians.
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COVID-19 Portal While this global health crisis continues to evolve, it can be useful to look to past pandemics to better understand how to respond today.
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