Image by Mbari

In the deepest darkest parts of the ocean, there lurks an astonishingly peculiar creature. It seems as though the Pacific barreleye could only be conjured up by an imaginative madman!

Here is an underwater horror story that will have you thinking twice before your next deep dive! The creature in question is the Pacific barreleye fish (Macropinna microstoma), also known as a spookfish (and with good reason). It is unlike anything you have ever seen before! The creature’s most noticeably odd feature is its large, barrel-shaped, tubular eyes that are topped with huge, green glowing lenses. It gets stranger – these barrel-like eyes are located inside a transparent, fluid- filled, dome-like head. To complete the creepy package, what looks to be a second set of beady little eyes on the front of its head is, in fact, not eyes at all, but rather the barreleye fish’s huge nostrils!

The Pacific barreleye fish, only a few centimetres in length, is equipped with sensitive binocular vision, allowing it to survey the waters above. Accustomed to living in the pitch black of the deep seas (at a depth of more than 600m), the animal has developed a unique and very unusual ability – it can see through its transparent head. This ghoulish fish will wait, motionless in the darkness, using its flat fins for stability, and lie with its body in a horizontal position with its eyes peering upwards. The green pigments in its eyes filter out sunlight coming directly from the sea surface, helping the barreleye spot the bioluminescent glow of jellies or other animals directly above. When it spots its prey, the fish rotates its eyes forward and quietly swims upward, in full-on feeding mode.

The barreleye fish is not only a frightening image, but also shows no terror in the face of danger. It is willing to steal food from siphonophores (elongated relatives of jellyfishes) by using its fins to manoeuvre itself precisely through the maze of poisonous tentacles, picking off any captured organisms. The transparent dome not only allows them to see all around them and choose the best path to victory, but it also protects their eyes from the stings.

Are you wondering how you may have never heard of this creature before? The fish has been known since 1939, but only from mangled specimens dragged to the surface by nets. Humans were not aware of its strange features because once brought to the surface, the transparent dome would collapse. It was only in 2004 that scientists were able to bring a live specimen to the surface with its dome still intact. They were then able to study the fish’s bizarre behaviour and share it with the rest of the world. Now it is your turn to spread this bizarre news!