This deep-sea fish uses weird eyes to see in dark and light

The pearlside contradicts previously held ideas about rods and cones

pearlside fish

FISHEYE  Fish called pearlsides (Maurolicus muelleri, shown) have eyes adapted to see well in both the murky depths of the ocean and in brighter light at the surface.

Wen-Sung Chung/University of Queensland

Light-sensitive cells in the eyes of some fish do double-duty.