Glasshead Barreleye, Rhynchohyalus natalensis (Gilchrist & von Bonde 1924)

A Glasshead Barreleye, Rhynchohyalus natalensis, taken in a deep-sea trawl in the Southern Tasman Sea Abyssal Basin between 800-1000 m depth. The red arrows in the lower right figure indicate the notch in the cornea of the "second eye". Source: Adrian Flynn, in Partridge et al 2014 Proc. R. Soc. B 281: 20133223. License: CC by Attribution


The remarkable Glasshead Barreleye, found in the oceanic "twilight zone", has bi-directed eyes capable of seeing above and below. The barreleye has a conventional refractive lens on top of its head to see predators and prey that are silhouetted against the dim light filtering down from above. It also has a curved mirror-like lens and retina that sees the flashes of bioluminescence from fishes and invertebrates to the side and below, giving the fish a much larger field of view.

Cite this page as:
Dianne J. Bray, Rhynchohyalus natalensis in Fishes of Australia, accessed 14 Jul 2024,

Glasshead Barreleye, Rhynchohyalus natalensis (Gilchrist & von Bonde 1924)

More Info


Recorded in Australia from off Norah head to off Nowra, New South Wales. Elsewhere, the species is circumglobal in temperate mesopelagic waters. 

Species Citation

Hyalorhynchus natalensis Gilchrist & von Bonde, 1924. Rept Fish. Mar. Biol. Surv. Union South Africa 3(7): 4, pl. 1(1). Type locality: off Table Bay, South Africa, depth 135 fathoms.


Dianne J. Bray

Glasshead Barreleye, Rhynchohyalus natalensis (Gilchrist & von Bonde 1924)


Barnard, K.H. 1925. A monograph of the marine fishes of South Africa. Part 1. (Amphioxus, Cyclostomata, Elasmobranchii, and Teleostei — Isospondyli to Heterosomata). Annals of the South African Museum 21(1): 1-418 figs 1-18 pls 1-17

Bertelsen, E., Theisen, B. & Munk, O. 1965. On a postlarval specimen, anal light organ, and tubular eyes of the argentoid fish Rhynchohyalus natalensis (Glichrist and von Blonde). Videnskabelige Meddelelser fra Dansk Naturhistorisk Forening i Kjøbenhavn 128: 357–371.

Cohen, D.M. 1964. Suborder Argentinoidea. In, Olsen, Y.H. (ed.) Fishes of the Western North Atlantic. Memoir. Sears Foundation of Marine Research 1(4): 1-70 figs 1-20

Gilchrist, J.D.F. & von Bonde, C. 1924. Special report No. 7. Deep-sea fishes procured by the S.S. Pickle (part 2). Report. Fisheries & Marine Biological Survey, Union of South Africa 3: 1-24 pls 1-6.

Okiyama, M. 1993. An atlas of the early stage fishes in Japan. Koeltz Scientific Books, Germany. 1154 pp. (in Japanese)

Partridge, J.C., R.H. Douglas, N.J. Marshall, W.-S. Chung, T.M. Jordan & H.-J. Wagner. 2014. Reflecting optics in the diverticular eye of a deep-sea barreleye fish (Rhynchohyalus natalensis). Proceedings of the Royal Society B 218(1782): doi: 10.1098/rspb.2013.3223 PDF

Paxton, J.R., Gates, J.E., & Bray, D.J. 2006. Opisthoproctidae. pp. 371-372 in Beesley, P.L. & Wells, A. (eds). Zoological Catalogue of Australia. Volume 35 Australia : ABRS & CSIRO Publishing Parts 1-3, 2178 pp.

Quick Facts

CAAB Code:37099002

Biology:Bi-directed eyes

Depth:250-1000 m


Max Size:18 cm TL

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