Macropinna microstoma is the only species of fish in the genus Macropinna, belonging to the Opisthoproctidae, the barreleye family. It is recognized for a highly unusual transparent, fluid-filled dome on its head, through which the lenses of its eyes can be seen. The eyes have a barrel shape and can be rotated to point either forward or straight up, looking through the fish’s transparent dome. M. microstoma has a tiny mouth and most of its body is covered with large scales…. The fish normally hangs nearly motionless in the water, at a depth of about 600 metres (2,000 ft) to 800 metres (2,600 ft), using its large fins for stability and with its eyes directed upward. In the low light conditions it is assumed the fish detects prey by its silhouette. MBARI researchers Bruce Robison and Kim Reisenbichler observed that when prey such as small fish and jellyfish are spotted, the eyes rotate like binoculars, facing forward as it turns its body from a horizontal to a vertical position to feed. Robison speculates that M. microstoma steals food from siphonophores.
M. microstoma has been known to science since 1939, but is not known to have been photographed alive until 2004. Old drawings do not show the transparent dome, as it is usually destroyed when brought up from the depths.
LiveScience.com (2009-02-23). “Strange fish has a see-through head”
. MSNBC.com. Retrieved 2009-02-24.
Kim Fulton-Bennett (2009-02-23). “Researchers solve mystery of deep-sea fish with tubular eyes and transparent head”
. Retrieved 2009-02-24.
Froese, Rainer and Pauly, Daniel, eds. (2012). “Macropinna microstoma”
in FishBase. February 2012 version.
Robison, Bruce H.; Reisenbichler, Kim R. (2008). “Macropinna microstoma and the Paradox of Its Tubular Eyes”. Copeia. 2008 (4): 780–4. doi:10.1643/CG-07-082
. JSTOR 25512162
McFall-Ngai, Margaret; Ding, Lin; Childress, James; Horwitz, Joseph (1988). “Biochemical Characteristics of the Pigmentation of Mesopelagic Fish Lenses”
. Biological Bulletin. 175: 397–402. doi:10.2307/1541731
. JSTOR 1541731
Crescitelli, Frederick; McFall-Ngai, Margaret; Horwitz, Joseph (1985). “The visual pigment sensitivity hypothesis: Further evidence from fishes of varying habitats”. Journal of Comparative Physiology A. 157 (3): 323–33. doi:10.1007/BF00618122
Schwab, Ivan R.; Ho, Viet; Roth, Alan; Blankenship, Thomas N.; Fitzgerald, Paul G. (2001). “Evolutionary attempts at 4 eyes in vertebrates”
(PDF). Transactions of the American Ophthalmological Society. 99: 145–56; discussion 156–7. PMC 1359005
Freely accessible. PMID 11797302
Schwab, Ivan R. (2011). “Barreleye, Macropinna microstoma”
. Evolution’s Witness: How Eyes Evolved. Oxford University Press. pp. 101–2. ISBN 978-0-19-536974-8.