The mythological creatures that could transform themselves into ravens, swans, and wolves were valkyries celtic warrior-goddesses amazons none of these; mythological creatures could only take one form

The Valkyries were the mythological creatures that could transform themselves into ravens, swans, and wolves. A valkyrja is a term used to describe an often beautiful female figure that is also a soldier of battle, sometimes described as having wings themselves or getting about by riding a magnificent winged horse. They are portrayed carrying various weapons, almost always accompanied by a shield, sword and or spear. 

Cell division is important to single celled organisms because it allows the cells to reproduce. through cell division, cells make exact copies of themselves. when single celled organisms go through cell division, they make exact copies of themselves which is how they reproduce.