Fish are aquatic animals that are characterized by their streamlined, often scale-covered bodies and their ability to breathe underwater using gills. They are a diverse group of animals, with more than 34,000 species known to science. Fish can be found in almost every aquatic environment on Earth, from deep ocean trenches to mountain streams. They come in a wide variety of shapes and sizes, from tiny, translucent gobies to massive, predatory sharks. Many fish have adaptations that help them survive in their specific environments, such as camouflaging coloration, powerful jaws and teeth for catching prey, or elongated bodies for swimming quickly through open water. In general, fish are ectothermic, meaning their internal body temperature is regulated by their environment rather than their metabolism. This allows them to thrive in a wide range of water temperatures, but also means they are vulnerable to sudden changes in temperature and other environmental factors.
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