The defensive behaviors introduced in the above two sections all refer to actions taken by individual fish, and defensive behaviors can also be social behaviors. Living in groups is also a form of defense. Fish often gather in large groups. When encountering a predator, although some individuals in the fish group are preyed on, the total number of individuals preyed on is less than the total number of individuals preyed on in a dispersed state. And it’s not easy for predators to easily chase a target in a large school of fish. In addition, in a school of fish that lives in aggregation, when any individual detects danger, it sends an alarm signal, and all members can jump together.
When fish perform defensive behaviors, they often affect the performance of other behaviors. Often effective defense is carried out in coordination with attack, and is an adaptive behavior in the evolutionary development of species. During the evolution of species, only individuals that can effectively attack and defend can survive and reproduce.
