When an animal pricks its ears up, or when its ears prick up, it puts its ears up straight because it is listening carefully to a small sound or one that is far away.

If you prick up your ears, or if your ears prick up, you suddenly begin to listen very carefully because you have heard something interesting.

I overheard them mentioning my name and pricked up my ears. 我无意中听到他们提起我的名字后就竖起耳朵仔细听。