The Bodacious Pacific Barreleye!!! Episode 3

Welcome back to Weird Fish of the Week, today’s contestant will stare back at you as much as you stare at them, welcome the Pacific Barreleye!

photo credits 2004 MBARI

INTRODUCTION

The macropinna microstoma was discovered in 1939, but wasn’t seen alive until the 1990s. They live at depths of 1,800-2,600 feet (~550-800 m) where the sunlight starts to fade to darkness. As their name suggests, the Pacific barreleye inhabits the waters of the Pacific Ocean. Scientists don’t know a lot about the fish; most of our recent knowledge came from the MBARI, when a specimen caught in a trawl survived for hours in an aquarium on board, allowing researchers to observe the fish.

ANATOMY/PHYSIOLOGY

The majority of this rather small fish (averaging around 6 inches) sports a dull brown look, with a very small mouth and two olfactory organs that are equivalent to our noses, but your eyes are quickly drawn to that galactic dome on its head. The barreleye has a very small mouth and two olfactory organs that are equivalent to our noses. The barrel shaped eyes it’s named after rotate in its head, allowing it to peer up at the silhouettes of food or forward (this was only discovered after that MBARI trawl, it was thought to have stationary eyes prior). The eyes are very sensitive to light and it's thought that the green pigment in them filters out green rays from the sun, assisting them in spotting prey. That clear dome on its head is thought to protect those eyes from the sting of siphonophores they steal food from. The barreleye also sports large flat fins, providing it great precise mobility and the ability to lie perfectly still in water. 

FOOD

Most of the barreleye’s diet is speculation. The particularly small mouth and large digestive system leads to the belief they eat zooplankton, and a lot of it. Lots of plankton can be found caught in the stingers of siphonophores, so a common theory is the fish steals food off of the siphonophore very carefully, and that soft tissue dome protects its eyes in the process. 

The two holes where one might think its eyes are are its olfactory organs. photo credits MBARI 2004

PERSONAL REVIEW

I only have one word for this fish: absolutely stunning. I stare at this fish like a deer caught in headlights. While not one of my personal favorites, I cannot help but admire the sheer beauty in that dome. I see the transparent dome as similar to an astronaut with the galaxy in its helmet, it’s so impressive and fascinating how a creature like this came to be, how it evolved to be perfectly boring until that showstopper of a head. Solid 10/10 design, I cannot help but be mesmerized by the beauty of the world around me when I look into this fish’s eyes. 

That’s all for this week. See you next time on Weird Fish of the Week! I encourage you to look more into this fish if it caught your eye. It’s only one of the many gorgeous beings in our oceans. 

(498 words)

REFERENCES

National Marine Sanctuary Foundation. (2022, January 26). Sea Wonder: Barreleye. National Marine Sanctuary Foundation. https://marinesanctuary.org/blog/sea-wonder-barreleye/

B. H. Robison and K. R. Reisenbichler. Researchers solve mystery of deep-sea fish with tubular eyes and transparent head. Monterey Bay Aquarium Research Institute. https://www.mbari.org/barreleye-fish-with-tubular-eyes-and-transparent-head/