Bathylychnops exilis, the Javelin spookfish, is a species of barreleye found in the northern Pacific and in the eastern Atlantic Ocean near the Azores where it is found at depths of around 640 metres (2,100 ft). This species grows to a length of 50 centimetres (20 in) SL.[2]
| Bathylychnops exilis | |
|---|---|
| |
| Javelin spookfish | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Argentiniformes |
| Family: | Opisthoproctidae |
| Genus: | Bathylychnops |
| Species: | B. exilis
|
| Binomial name | |
| Bathylychnops exilis | |
The species is notable for unusual protuberances that grow from its eyes, which each have "a well developed lens"[3] and a retina, and which have led to the species being called a "four-eyed" fish.[3] They have two spherical eyes that are dorsally directed and two secondary eyes that are ventrally directed.[4] It has been suggested that the purpose of these extra eyes is detection of threats from below, since these eyes point downwards.[5] The Javelin spookfish have a distinct and advantageous secondary globe to their eyes. They use mirrors to collect and focus light, instead of a lens to divert the path of light. This feature provides great benefits in their chances for survival.[6][7]
References
edit- ^ Cohen DM (1958). Bathylychnops exilis, a new genus and species of argentinoid fish from the North Pacific. Stanford Ichthyological Bulletin 7, 47-52.
- ^ Froese, Rainer; Pauly, Daniel (eds.). "Bathylychnops exilis". FishBase. February 2012 version.
- ^ a b Pearcy WG, Meyer SL, Munk O (1965). A 'Four-Eyed' Fish from the Deep-Sea: Bathylychnops exilis Cohen, 1958. Nature 207, 1260-1262.
- ^ Partridge, J. C., et al. “Reflecting Optics in the Diverticular Eye of a Deep-Sea Barreleye Fish (Rhynchohyalus Natalensis).” Proceedings: Biological Sciences, vol. 281, no. 1782, 2014, pp. 1–9. JSTOR, http://www.jstor.org/stable/43601696. Accessed 18 Mar. 2023.
- ^ Dawkins R (2009). The Greatest Show on Earth: The Evidence for Evolution. London: Bantam Press.
- ^ Pearcy, William G.; Meyer, Samuel L.; Munk, Ole (September 1965). "A 'Four-Eyed' Fish from the Deep-Sea: Bathylychnops exilis Cohen, 1958". Nature. 207 (5003): 1260–1262. doi:10.1038/2071260a0. ISSN 1476-4687. PMID 5884641. S2CID 4193190.
- ^ Stein, D. L.; Bond, C. E. (1985). "Observations on the morphology, ecology, and behaviour of Bathylychnops exilis Cohen". Journal of Fish Biology. 27 (3): 215–228. doi:10.1111/j.1095-8649.1985.tb04022.x. ISSN 1095-8649.
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