Dolphins are a kind of creature that we are more familiar with. Common dolphins live in the ocean and belong to marine organisms. In their long survival process, they have adapted to the organisms in the ocean. However, not all dolphins live in the ocean, and some live in freshwater. Freshwater dolphins are mainly distributed in the Ganges River, Indus River and Amazon River basins. However, due to environmental pollution and artificial hunting and other factors, the number of dolphins in freshwater has become less and less, and some have become extinct. For example, some freshwater dolphins originally lived in the Yangtze River Basin in China, but now they are extinct.
As mentioned above, most dolphins live in sea water, and a small number live in fresh water, but the number of dolphins in these fresh water continues to decrease. These dolphins, which originally lived in the ocean, could not survive in fresh water because they had adapted to the environment in the ocean. They maintain the balance of osmotic pressure in the body by swallowing seawater into their stomach; In addition, they have also adapted to the high salinity and high pressure environment in the marine environment. If they are exposed to fresh water, their physiological regulation mechanism will be out of order, and may even die in a short time.
However, for those dolphins that originally live in fresh water, they can survive in fresh water because their body structure and physiological regulation mechanism are adapted to the freshwater environment.
