The 27 Best Deep-Sea Species: #5 Barreleye Fish

#5 Species from the family Opisthoproctidae (Phylum: Chordata, Class: Actinopterygii, Order: Osmeriformes)

These fish are so cool they could be invertebrates.  First is that lovely family name which means behind the anus (opisthe-behind, prokotos-anus), a name whose intent escapes me.

Second, the 12 species in 6 genera are exclusively deep sea. Shallow water species can suck it! Third, all the species except one have tubular eyes that protrude from the skull, always gazing dreamily upwards. In Winteria (image left), the eyes look forward and up. Fourth, those crazy eyes have huge lens (yes size does matter) with an inordinate amoutn of rod cells and rhodopsin.  Fifth, they possess bioluminescent organs on their sides and stomachs that serves a counterillumination from below.


The last and best reason yet, is that all the species have transparent to translucent heads!  You can just look right in there and see all the fish’s thoughts in that tiny little fish brain. The two thoughts so far documented are I am hungry and horny.  Same as Kevin really.  Seriously though, the clear heads presumably allow the fish to collect more light.

Check out the pictures of Opisthoproctus soleatus by Norbert Wu Middle image of Macropinna microstoma from Paul Yancey.

Barreleyes at 5:47

Dr. M (1714 Posts)

Craig McClain is the Assistant Director of Science for the National Evolutionary Synthesis Center, created to facilitate research to address fundamental questions in evolutionary science. He has conducted deep-sea research for 11 years and published over 40 papers in the area. He has participated in dozens of expeditions taking him to the Antarctic and the most remote regions of the Pacific and Atlantic. Craig’s research focuses mainly on marine systems and particularly the biology of body size, biodiversity, and energy flow. He focuses often on deep-sea systems as a natural test of the consequences of energy limitation on biological systems. He is the author and chief editor of Deep-Sea News, a popular deep-sea themed blog, rated the number one ocean blog on the web and winner of numerous awards. Craig’s popular writing has been featured in Cosmos, Science Illustrated, American Scientist, Wired, Mental Floss, and the Open Lab: The Best Science Writing on the Web.

3 comments on “The 27 Best Deep-Sea Species: #5 Barreleye Fish
  1. “First is that lovely family name which means behind the anus (opisthe-behind, prokotos-anus), a name whose intent escapes me.”

    I suspect its latin for “ass-backwards”

Comments are closed.