Fishy Fish Eyes

One denizen of the deep uses a mirror inside its peepers

Piscine Vision

Sight for four eyesTamara Frank (Zoom out!)

The brownsnout spookfish is not like other fish.

This deep-sea dweller's eyes have two segements, one of which, in contrast to all other vertebrates, has mirrors instead of lenses to accurately image its surroundings.

The normal, lens-equipped part [orange globes] sees above the fish; the mirrored part [black dots] sees to the sides and below.

Researchers caught the spookfish by chance during a deep-sea-observing tour. "It was obvious [from its appearance that] the fish was a bit weird," says Julian Partridge, a zoology professor at the University of Bristol in England who was part of the team that caught the fish and discovered the secret of its eyes. He is now reconstructing the eye in hopes of determining its visual acuity and whether the mirrors contribute any distinct advantages.