Only amphibious animals can freely move from salt water to land and vice versa. And in general, only mangroves of various varieties are able to grow with green leaves, flower and bear fruit in salt water. Even though other plants grow on beaches, they must be kept at a certain distance to avoid salt water. But some flowering plants are bold enough to grow very close to it. And therefore, some flying insects may be present there to clarify the final boundaries of the land.
