There are many species inside water. Each animal inside water has different respiratory system. Few animals breathe through their gills while few breathe directly through their skins. Oxygen gets dissolved in water.
Aquatic animals extract this oxygen to maintain their respiration. Normal living beings that live on earth except amphibious animals can not breathe inside water.
Similarly these aquatic animals can not breathe on ground. Amphibious animals are those who live on ground as well as inside water. They have provision to breathe both inside the water as well as on the ground.
Aquatic life is very different in all respects than normal living beings. These animals are soft and delicate. Some of these are so delicate that they can die even from a small push. Therefore it is necessary to be aware of their life.
Aquatic life is a beautiful life if think deeply. This aquatic life increases the beauty of this nature. They are an indispensable part of this nature. If aquatic life is so important then everyone must take good care of it.
Aquatic animals have added colors to this environment and this has given a wide scope to the beauty of this nature. Nature is nothing without aquatic life. If aquatic life is disturbed then the colors of this nature may get stolen.