Freshwater dolphins are found living in rivers and lakes in South America, as well as east and southeast Asia. These dolphins have unique features, habitats and hunting skills that have evolved to fit their freshwater demands. Sadly, as humans spread and develop, the habitats housing these creatures dwindle in resources, along with the dolphin populations themselves.
There are several species of dolphins living in freshwater: the Amazon river dolphin, tucuxi, Ganges river dolphin, Indus river dolphin and Irrawaddy dolphin. All of these dolphin species are classified as either vulnerable, endangered or critically endangered by the World Wildlife Fund. The Yangtze river dolphin was listed as extinct as of 2006. There is also one species of freshwater porpoise, the finless porpoise, which is endangered.
Freshwater river dolphins share similar appearances and features, such as long, thin snouts. These dolphins also vary in physical characteristics, such as size and body color. Amazon river dolphins are the largest of all freshwater dolphins, growing up to 10 feet long. Most freshwater dolphins weigh no more than 250 pounds, according to the WWF. Unlike other freshwater dolphins that are grey to brown in color, Amazon river dolphins are light pink.
Freshwater dolphins all have one thing in common in terms of their environment, and that is they live and breed in freshwater. However, the different species of freshwater dolphins live in different habitats. The Amazon river dolphin is found in South America's Amazon and Orinoco river basins. This dolphin prefers faster clear, white or black water rivers. It is also found swimming in lakes and tributaries, and sometimes in flooded forests. On the other hand, the tucuxi, which is also found living in the Amazon and Orinoco rivers, prefers to swim in shallow estuaries and bays and avoids faster waters and flooded forests. The Ganges river dolphin is found in rapid, clear water river systems traveling through India, Nepal and Bangladesh. The Indus river dolphin lives along the Indus river and its tributaries and channels in Pakistan. The freshwater Irrawaddy dolphin is found swimming in southeast Asia in shallow river systems. The extinct Yangtze dolphin was found in China's freshwater lakes and rivers. Finless porpoises are also found in southeast Asia.
Feeding and Eating Habits
Freshwater dolphins generally feed on the same food types. Most species prey upon fish, freshwater sharks, shrimp, clams, turtles and crabs. Each species has its own customized way of hunting for prey. Amazon river dolphins have poor eyesight and rely on an internal sonar system to find food. Since they are blind, Indus river dolphins rely on echolocation, or sound waves, to find prey. Ganges river dolphins swim on their sides along river bottoms, using their flippers to find prey as they drag along in the mud.
Freshwater dolphin populations are under much concern due to their dwindling environments and resources, mostly as a result of human activity like fisheries, mining, pollution, deforestation and hydroelectric developments. Fisheries remove many of the food sources that freshwater dolphins depend on, and fisherman also catch and kill dolphins for bait or they die after getting tangled in fishing nets. The Whale and Dolphin Conservation and other animal welfare assemblies are working to educate locals in freshwater dolphin habitats on the importance of conservation.
Amanda Williams has been writing since 2009 on various writing websites and blogging since 2003. She enjoys writing about health, medicine, education and home and garden topics. Williams earned a Bachelor of Science in biology at East Stroudsburg University in May 2013. Williams is also a certified emergency medical technician.