Animals aren't really Yin, alot of animals can be described as yin, though. Yin is like the black side of the yin and yang symbol. Yin is sometimes described as very feminine, mysterious, dark, and negative. One animal that I can think of, that could be both yin and yang is a snake. A snake is quiet, mysterious, and clever, but it is also strong, and masculine. An animal that would definetly be yang is a monkey, because they are very noisy and wild.