Introduction to the finless porpoise: The finless porpoise is lead-gray or off-white in color and is a national second-level protected animal. The finless porpoise is well-known for its "smile". The Yangtze finless porpoise is the only freshwater subspecies of the finless porpoise. It is only distributed in the middle and lower reaches of the Yangtze River and in areas such as Dongting Lake and Poyang Lake. It has lived on the earth for 25 million years.