Dolphins are widely spread all over the world, as they live in many oceans and seas of the planet, except for the Caspian Sea and the Aral Sea.
Most species are found in temperate and tropical regions, although they can live from the equator to the circumpolar regions. They also live in several major river systems, including the Indus, Ganges, and Amazon.
Obviously, habitat is different for each dolphin species, but generally, these mammals avoid extremely cold waters, so they are not found in polar regions.
Most of them live in saltwater, but some species thrive in freshwater as well. Dolphin habitats vary depending on environmental factors and food availability. They are intelligent creatures with a high level of intelligence that can change habitats when necessary for survival.
For example, common bottlenose dolphins live in all oceans, and they tend to live close to the shoreline. Migration is an important part of the life of some dolphin species. They must migrate to where there is enough food; this is why in some places where dolphins used to be, they either become very scarce or disappear altogether. Even changes in water temperature can cause them to leave the places that once were home to them.
The Atlantic, Pacific, and Indian Oceans, and their seas contain a large number of dolphin species because they have warm waters. Also, some species are distributed over large areas, while others may be endemic exclusively to certain regions of the ocean.