Whales are marine mammals and make up part of the cetacean family which includes all species of whale, dolphin and porpoise.
As marine mammals whales breathe air, produce milk, give birth and are warm-blooded animals.
In fact all known species of whale live and thrive in saltwater environments.
First to help clarify this topic there are a few species of dolphin that live and survive in freshwater such as the amazon river dolphin, Ganges river dolphin and Indus river dolphin, but there aren’t any species of whale that live in freshwater.
Whales and their prey have biologically adapted to the natural properties of saltwater.
Saltwater contains salts and minerals which help to clear out infection and aid in healing cuts or wounds that a whale may incur due to an injury or fight with a shark or killer whale.
Saltwater also contains the majority of food whales consume, which generally come from the ocean, not freshwater rivers.
In fact one reason that could affect a whales ability to survive indefinitely in freshwater has to do with the fact that the whale would be unlikely to find sustainable quantities of food in a shallow freshwater environment.
In contrast to freshwater environments the salty ocean is large and expansive allowing whales to make deep dives and can assist the whale with rising to the surf since saltwater has more buoyancy than freshwater.
Whales (especially those in large pods) need lots of space to survive and prosper which in most cases can only be found in the salty ocean.
Aside from these facts there are a number of freshwater environments that are littered with pollution, boats and fishing nets.
Even some of the dolphin species are declining due to the increased difficulty they are facing in freshwater environments.
There are likely other unexplored and unanswered reasons for why whales thrive in saltwater but become weak and unable to live in freshwater for extended periods of time, however the answers to these questions will only be uncovered as we continue to learn more about these amazing majestic animals.
So to some it all up freshwater is too shallow, lacks large supplies of food needed for survival, can hazardous and is too small of an environment for whales to live in.
With that said whales have been known to travel to freshwater locations on occasion and may pass through a freshwater area when migrating or traveling through the ocean, however they do not stay for very long and eventually return back to the ocean.
In fact although whales cannot live in freshwater for long periods of time there is an instance of a whale which goes by the name of “Humphrey the whale” that survived and lived in freshwater for several weeks, but eventually he became very weak and sick and was eventually guided back to the ocean with the help of humans.
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