The balance of two muscle groups in the iris changes how big your pupils are, like a camera aperture.

虹膜中两个肌肉群的平衡会改变你的瞳孔大小， 就像相机光圈一样。

This meter-long predator was only a threat to worms on the seafloor, but with 11 pairs of fins, grasping appendages, and a mouth like a camera aperture, it looked menacing enough to star in its own horror movie franchise.

这种一米长的捕食者只对海底的蠕虫构成威胁，但它有 11 对鳍、抓握的附属物和一张像相机光圈一样的嘴，看起来足够险恶，足以在它自己的恐怖电影系列中出演。