Fish are aquatic vertebrates, and their physiological characteristics and behaviors are very different from those of terrestrial animals such as mammals and birds. A common question is: Do fish sleep? If so, how do they sleep? Since fish do not have eyelids, they do not close their eyes when they s...
Fish are one of the oldest vertebrates on Earth, with an evolutionary history of more than 500 million years. They have adapted to almost all aquatic environments, from freshwater lakes to the deep sea, from tropical coral reefs to the icy polar seas. The unique body structure and physiological func...