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


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

The pearlside contradicts previously held ideas about rods and cones

3:25pm, November 9, 2017
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.

Light-sensitive cells in the eyes of some fish do double-duty. In pearlsides, cells that look like rods — the stars of low-light vision — actually act more like cones, which only respond to brighter light, researchers report November 8 in Science Advances. It’s probably an adaptation to give the deep-sea fish acute vision at dawn and dusk, when they come to the surface of the water to feed.

Rods and cones studding the retina can work in tandem to give an animal good vision in a wide variety of light conditions. Some species that live in dark environments, like many deep-sea fish, have dropped cones entirely. But pearlside eyes have confused scientists: The shimmery fish snack at the water’s surface at dusk and dawn, catching more sun than fish that feed at night. Most animals active at these times of day use a mixture of rods and cones to see, but pearlside eyes appear to

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