The Baiji white dolphin, also known as the Chinese River Dolphin, can only be found in the Yangtze River in China. This mammal can grow up to 8 feet long and weigh up to 1.4 tons. They rely on echolocation for navigation and search due to their small eyes and poor eyesight. Baiji white dolphins lived in the Yangtze River for about 20 million years, their numbers plummeting from the 1950s onwards. As industrialization in China developed, the river was used for fishing, transportation and hydroelectricity, which greatly affected the livelihoods of mammals. Although not officially recorded as extinct, no one has seen the Yangtze River dolphin since 2002.