Bony-eared assfish


The bony-eared assfish is a bathypelagic species of cusk-eel found in tropical and sub-tropical oceans at depths of from. It has been found as far north as Queen Charlotte Sound off British Columbia's coast. This species grows to a length of SL. It is the only known member of its genus Acanthonus.
The bony-eared assfish holds the record for the smallest brain-to-body weight ratio of all vertebrates.
Like many other creatures that dwell in the depths of the sea, the bodies of assfish are soft and flabby, and their skeletons are light and reduced. This is likely to have resulted from a lack of food and the high pressures which accompany living at such a depth, making it difficult to generate muscle and bone.

Etymology

In 1887, German ichthyologist Albert Günther gave the species its scientific name. Armatus means "armed" in Latin, likely chosen because the fish sports spines off the tip of the nose and the gills. This also perhaps accounts for the "bony-eared" bit, according to Gavin Hanke, curator of vertebrate zoology at the Royal British Columbia Museum in Victoria, British Columbia. Akanthos is Greek for "prickly", and onus could either mean "hake, a relative of cod", Hanke says, "or a donkey". Adam Summers, associate director at the Friday Harbor Laboratories at the University of Washington, concurs, saying onus could easily read "as a homonym of the Greek word for ass".