The remarkable Barreleye Fish and its transparent skull

This rare fish dwells in the deep twilight zone of the ocean. The fish has green eyes that often appear to be looking up through their transparent heads, these eyes are highly light sensitive. Though many fish in the deep are hard to find hidden by their bioluminescence, this fish is one head of the others, with its light sensitive eyes it can easily track down even the harder prey, for its pigment in its eyes help define what is light and what is bioluminescence.

Scientists have recently observed dead specimens of this fish. This made them pose a question: Why is it always looking up? This question was only answered when the fish was observed up close. Its eyes could rotate! And, in a remarkably high number of degrees in all directions.

Their eyes are protected by a transparent shield to protect them from other fish, and the stinging tentacles of one of its preys, the Siphonores.

An expert of marine biology, Bruce Robinson has had this career for 30 years, and he has only seen this fish alive around eight times! “We do spend a lot of time exploring down there, so I can say with some confidence that they’re quite rare,” he said to The Guardian’s interviewer.

References:

Information and picture 1: Scales, Helen. “Discovered in the Deep: The Incredible Fish with a Transparent Head.” The Guardian, Guardian News and Media, 31 Aug. 2022, https://www.theguardian.com/environment/2022/aug/31/barreleye-incredible-fish-with-a-transparent-head.

Picture 2: Unknown Author. “Brilliant Deep-Water Siphonophore.” H2O IQ, 8 June 2017, https://www.h2oiq.org/brilliant-deep-water-siphonophore/.