What’s in a Name? A Funny-Named Fish Teaches Us, by Don Orth

After a new museum exhibit opened on the Bony-eared Assfish (Acanthonus armatus), the story of this strange fish name went viral.   Although no one knows the origin of the name, it was a chance to laugh at the expense of the assfish.

Bony-eared Assfish (Acanthonus armatus) photo by Horn et al. (1978)

There are many appropriate common names that perfectly describe the fishes.  Consider, for examples, the Bluestriped Grunt, Vampirefish, Tigerfish, Anglerfish, Blobfish, Oarfish, Lancetfish, and other common names that aren’t so common.  Other common fish names require some explanation, such as the Sarcastic Fringehead, Tassel Snouted Flathead , Patagonian Toothfish, Darwin’s Slimehead, and the Slippery Dick.  Finally, some common names reflect descriptors given by indigenous people, such as the menhaden, mummichog, muskellunge, tautog, and cisco. A few common names need tutorials to learn how to pronounce it.  My favorite is the Humuhumunukunukuapua’a  (say “who-moo-who-moo-noo-koo-noo-koo-ah-pooah-ah”).   Better yet, listen to Don Ho sing about it! 
 

Science communicators missed the chance to teach about the fishes, using the hook of an unusual fish name to lure in the uninformed.  Here I briefly describe what the fishes, similar to the Bony-eared Assfish, can teach us. What matters most is what something is, not what it is called!   There is deeper meaning hidden within this fish.  If the Bony-eared Assfish could speak, it would say “I am more than my silly name!”

From Shakespeare's Romeo and Juliet, 1600, Juliet says:

'Tis but thy name that is my enemy;

Thou art thyself, though not a Montague.

What's Montague? it is nor hand, nor foot,

Nor arm, nor face, nor any other part

Belonging to a man. O, be some other name!

What's in a name? that which we call a rose

By any other name would smell as sweet;

So Romeo would, were he not Romeo call'd,

Retain that dear perfection which he owes

Without that title. Romeo, doff thy name,

And for that name which is no part of thee

Take all myself.

So let us give this fish its proper recognition.  It is a member of the Cusk-eel family (Ophidiidae). Cusk-eels are elongate fish with dorsal and anal fins that are continuous with the caudal fin and all the rays are similar in height.  The Cusk-eels possess a single chin barbell and some have small pelvic fins in throat region.  Some, like the Bony-eared Assfish have opercular spines.  This body form is well adapted for bottom dwelling.  The family has a worldwide distribution.  Other Cusk-eels burrow in sand during day or or live in permanent darkness. Most are deep-water specialists of the bathypelagic zone.  They are rarely encountered because sampling fishes at these depths is very challenging. 

The Bony-eared Assfish is a close relative to the pearl fish (aka assfish) in the family Carapidae.  These fish adapted to extreme habitats by becoming parasites of sea cucumbers and other marine invertebrates. The Pearlfish really does live in the ass of another animal. Just watch this odd behavior of the pearl fish as it enters the anus of the sea cucumber.    Some Cusk-eels are important commercial and recreational fish, others are commensal with invertebrates, others are notable sound producers, and still others have a fluid-filled cranium to facilitate buoyancy.  One Cusk-eel, called Abyssobrotula galatheae, holds the depth record for any fish at 8,370 m.   
 

Cusk-eels are rarely targeted by fisheries; rather they are typically caught as bycatch.   One Cusk-eel, has a commensal relationship with the pancake urchin. But the Cusk-eels are phenomenal sound producers. The sound producing apparatus was described in the Ophiodon rochei by Parmentier et al. (2010); it involves muscles with fast twitch fibers attached to bones that drum the swimbladder.  The  Striped Cusk-eel Ophiodon marginatum makes stereotypical calls indicative of courtship and spawning (Mann et al. 1997; Mooney et al. 2016). This discovery permits scientists to monitor the species using acoustic signals instead of invasive or extractive sampling methods. You can listen to their sounds here.  

Sound producing apparatus in Ophiodon rochei.  Source: Parmentier et al. (2010)

The Bony-eared Assfish lacks a swimbladder and maintains neutral buoyancy by means of greatly reduced muscle and bone mass and a cranium filled with a low-density fluid (Horn et al. 1978).  Because the head contains the heavier elements of the body, it makes sense to localize the low-density fluid in the enlarged cranial cavity.   The large head, especially with the opercular spines, discourages predation and expands the range of prey that can be engulfed by the Bony-eared Assfish. Bony-eared Assfish  have only been collected in the bathypelagic zone, from 1,171 to 4,415 m deep.  Fine et al (1987) discovered that the Bony-eared Assfish have the smallest brain per unit body weight and the largest semicircular canals of any known teleost, and possibly any vertebrate. Consequently, the dominant sensory system would appear to be the fish's lateral line. The huge cranial cavity also contains heavy saccular otoliths, indicative of sensitivity to low-frequency sound. The brain is specialized for one sensory system needed for the hovering and slow movement over the deep-sea floor.     

Outline of brain and semicircular canals in Acanthonus armatus. Source: Fine et al. (1987)

The second truth about this fish is that Günther did not use the “assfish” common name (see original text below).  Perhaps that came later.  

Günther (1878) original text description of
Acanthonus armatus.

The Bony-eared Assfish does not appear to live in the ass of invertebrates. This common name is not included in the authoritative 7^th edition of Common and Scientific Names of Fishes from the United States, Canada, and Mexico. This rare underwater video of the bony-eared assfish shows its slow life in the depths of the sea. What’s in a name? In this case, the name is an inaccurate source of ridicule.  It appears it’s past time to start a campaign to find a more appropriate common name for this unique fish. 

References

Fine, M.L., M.H. Horn, and B. Cox. 1987. Acanthonus armatus, a deep-sea teleost fish with a minute brain and large ears.  Proceedings of the Royal Society of London B 230:257-265.

Günther A. 1878. Preliminary notices of deep-sea fishes collected during the voyage of HMS Challenger. Annals and Magazine of Natural History, Series 5, 2:17-28. 

Günther A. 1887. Report on the deep-sea fishes collected by HMS Challenger during the years 1873-1876. In: Report on the scientific results of the voyage of HMS Challenger during the years 1873-76. Zoology, London 22:1-335.

Horn, M.H., P.W. Grimes, C.F. Phleger, and L.L. McClanahan.  1978. Buoyancy function of the enlarged fluid-filled cranium in the deep-sea Ophidiid fish Acanthonus armatus. Marine Biology 46:335-339.

Knudsen, S. 2015. Acanthonus armatus. The IUCN Red List of Threatened Species 2015: e.T190201A60796787. http://dx.doi.org/10.2305/IUCN.UK.2015-4.RLTS.T190201A60796787.en. Downloaded on 29 February 2016.

Mann DA, Bowers-Altman J, Rountree RA (1997) Sounds produced by the striped cusk-eel Ophidion marginatum (Ophidiidae) during courtship and spawning. Copeia 1997: 610−612

Mooney, T.A., M.B. Kaplan, A. Izzi, L. Lamoni, and L. Sayigh. 2016. Temporal trends in cusk eel sound production at a proposed US wind farmsite. Aquatic Biology 24:201-210. doi:10.3354/ab00650    

Parmentier E, Bouillac G, Dragi evi B, Dul i J, Fine ML (2010) Call properties and morphology of the sound-producing organ in Ophidion rochei (Ophidiidae). J Exp Biol 213: 3230−3236.