Dilated Pupils

DPupils expand into black disks nearly filling the iris. Pupil size is controlled by the autonomic nervous system — cats can't regulate it voluntarily. In dim light, dilation lets in more light; in bright conditions, sudden dilation means intense emotional arousal — possibly pre-hunt excitement or extreme fear. Check other signals: arched back + puffed fur = fear; low body + twitching tail = hunting excitement.