Family SCOPELARCHIDAE

Common name: Pearleyes

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Summary:
Voracious deep-sea predators with large dorsally directed tubular and semi-tubular eyes that allow them to hunt in the deep oceanic midwaters. Pearleyes are unique in having a“pearl-organ” or whitish spot on the eye that is associated with a secondary retina. This visual specialization increases their ability to see the bioluminescence emissions from other animals.

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Cite this page as:
Dianne J. Bray, Pearleyes, SCOPELARCHIDAE in Fishes of Australia, accessed 24 Apr 2024, https://fishesofaustralia.net.au/home/family/293

More Info

Family Taxonomy

 A relatively small family with five genera and about 18 species.

Family Distribution

 Found worldwide in all oceans except the Arctic and Mediterranean seas. Pearleyes inhabit the mesopelagic zone, usually in depths between 500-1000 m. They undertake daily vertical migrations towards surface waters to feed at night.

Family Description

Dorsal fin 5-10; Anal fin 17-39; Pectoral fin 18-28; Pelvic fin 9: Caudal fin 1+9+8+1; Branchiostegal rays 4+4; Vertebrae 40-65.

Body short to somewhat elongate, shallow to deep, slightly compressed; jaws large, tongue with a row of large teeth that are hooked posteriorly; scales cycloid, lateral line distinct with large pores.

Family Size

 Small to medium-sized fishes reaching 35 cm.

Family Feeding

 Pearleyes are voracious predators, feeding on other deep-sea fishes.

Family Reproduction

 Pearleyes are simultaneous hermaphrodites, with each individual having fully functional male and female reproductive organs - ovitestes.

Family Commercial

 Pearleyes are uncommon deep-sea fishes with no interest to fisheries. They are preyed upon by some of the larger sport fishes.

Family Remarks

 Images and MRI scans of the Shortfin Pearlyeye, Scopelarchus analis, can be viewed online at the Digital Fish Library. Pearleyes have a fossil record extending back to the Upper Cretaceous Period,

Author

 Dianne J. Bray

References

Collin, S.P., Hoskins, R.V. & Partridge, J.C.. 1998. Seven retinal specializations in the tubular eyes of the deep-sea pearleye, Scopelarchus michaelsarsi: a case study in visual optimisation. Brain, Behavior and Evolution 51: 291–314.

Davis, M.P. 2010. Evolutionary relationships of the Aulopiformes (Euteleostei: Cyclosquamata): a molecular and total evidence approach. pp. 431-470 in Nelson, J.S., Schultze, H.-P. & Wilson, M.V.H. Origin and Phylogenetic Interrelationships of Teleosts. München, Germany : Verlag Dr. Friedrich Pfeil 480 pp.

Davis, M.P. 2015. Evolutionary relationships of the deep-sea pearleyes (Aulopiformes: Scopelarchidae) and a new genus of pearleye from Antarctic waters. Copeia 2015(1): 64-71.

Digital Fish Library http://www.digitalfishlibrary.org/library/ViewSpecies.php?id=266

Goody, P.C. 1969. The relationships of certain Upper Cretaceous teleosts with special reference to the myctophoids. Bull. Brit. Mus. (Nat. Hist.) Geol., Suppl. 7, 255 pp.

Johnson, R. K.  1974. A revision of the alepisauroid family Scopelarchidae (Pisces: Myctophiformes). Fieldiana Zoology 66:  i-ix + 1-249.

Johnson, R. K.  1982. Fishes of the families Evermannellidae and Scopelarchidae: systematics, morphology, interrelationships, and zoogeography. Fieldiana Zoology (New Series) No. 12:  i-xiii + 1-252.

Johnson, R.K. 1984. Scopelarchidae, In Whitehead, P.J.P., M.-L. Bauchot, J.-C. Hureau, J.G. Nielsen & E. Tortonese. Fishes of the North-eastern Atlantic and the Mediterranean. Vol. 1. UNESCO, p. 1-510.

Johnson, R. K.  1986. Family No. 77: Scopelarchidae (pp. 265-267), In Smith, M.M. & P.C. Heemstra. Smiths' Sea Fishes. Macmillan, Johannesburg, South Africa. i-xx + 1-1047, Pls. 1-144.

Johnson, R.K. & Eschmeyer, W.N. 1998. P. 126, in Paxton, J.R. & Eschmeyer, W.N.. ed. Encyclopedia of Fishes. San Diego: Academic Press.

Wagner, H.J., Frӧhlich, E., Negishi, K. & Collin, S.P. 1998. The eyes of deep-sea fish II: functional morphology of the retina. Progress in Retinal and Eye Research 17: 637–685.