Did You Know?

This Fish Has a See-Through Head!

18th February, 2024


Forget what you think you know about fish – the barreleye has one of the weirdest adaptations in the ocean. Let's dive into its unusual anatomy: 

Eyes Like Telescopes:

They don't face forward! Instead, its tubular eyes are placed UPWARDS inside its domed, transparent head. They gather even the faintest light from above, perfect for the ocean's murky depths. 

Rotating Vision: 

The eyes can rotate both upwards AND forward!  Great for tracking down bioluminescent prey above or spotting food drifting downwards. 

Why The Transparent Head? 

That dome gives extra protection to those unique eyes. It's filled with fluid, like a protective shield. 

Deep-Sea Dweller: 

This fish hangs out 600 to 800 meters (2,000 to 2,600 ft) down in the ocean's twilight zone, where barely any sunlight filters. 

Sneaky  Ambush Hunter: 

It stays near motionless, eyes peering upwards, awaiting the faint silhouettes of jellyfish or tiny crustaceans; it then snags with its upward-facing mouth. 

Things Recently Figured Out: 

Barreleyes have been known since 1939, mostly from mangled specimens hauled up in nets that destroyed their transparent heads. In 2009, the Monterey Bay Aquarium Research Institute used deep-sea ROVs (remotely operated vehicles) to get the first proper footage of live barreleyes and confirm their amazing upward-facing then rotating eyes!