Also known as: 炸毛
An animal puffing up its body as a defense mechanism in a threatening situation in order to appear larger in size, to signal defensive aggression towards the enemy. In mammals, this is usually done alongside a Bent Back.
Often accompanied by Hissing. Though unlike hissing which is an offensive move almost always shown as a form of threat or anger, puffing up can be seen on other occasions such as fear or shock.