Figure 1. Etmopterus benchleyi, n. sp., paratype, USNM 421539, immature
male, 292 mm TL, fresh specimen Source
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Photophores are common
in most deep water fishes. These pores contain light filter pigments that generate light. It is hypothesized
that these ventrally located photophores are used like a mirror, to mimic or
reflect the blue ocean light above them, to help better camouflage them
(Denton, Herring and Widder 1985). These photophores are effective in making
light capable for the individual emitting it to see but while also camouflaging
it by mirroring the light from above them in the water column, which it an
effective technique for deep water dwelling fish.
When living at depths
of 836-1443 meters deep it is important to have some kind of ability to detect
prey. One of the fascinating characteristics used to detect prey and set it
apart from other deep water fish is it’s big glowing eyes relative to body
size. The eye is an elliptical shape with dimensions of 4.1mm-9.1mm in length
and 1.3mm-2.1mm in height. (Ebert, Long and Vasquez 2015) Having a big eye in
the deep ocean water where there is hardly any light wouldn’t be a very
effective hunting strategy of finding prey but since this fish emits its own
light/camouflage field having a large eye enhances the fish’s vision of prey
swimming nearby. The hunting strategy used by this fish are likely to be
similar to other lanternsharks. Other lanternsharks spend their time roaming
the benthopelagic parts of the ocean foraging for pelagic
macroplankton/micronenckton, teleost fish, and cephalopods (Neiva, Coelho and
Erzini 2006).
The Ninja Lanternsharks
uniform black color is unique when being compared to other deep water and
lanternsharks. Color in other deep water fish ranges from a red tint to a pale
gray. The behavior of this shark also aided into the naming process. The Ninja
shark slowly sneaks about and has an elusive behavior that helped give it its
ninja name.
Ninja Lanternshark Etmopterus benchleyi
n. sp., holotype, USNM 423195, adult female, 458 mm TL, fresh specimen. Source
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Another fascinating adaptation to help this
shark detect prey is its ampullae of lorenzini. These are sensory nerves on the
head of the shark that allow it to detect movements made by other fish nearby.
When combined with its photophores adding in visible light for the Lanternshark
and its big eye to also aid in finding prey it makes this shark an efficient
predator for deep water hunting. Other fish, such as catfish, have ampullae of
lorenzini but they don’t have the stealthy combination of camouflage and
hunting techniques that this shark does.
This species is a
unique deep water shark that fits its name. Living a life devoted to stealth
and hunting this shark is more resembling of a ninja than any other. Having a
pitch black colored body and photophore cell that act as a mirror to the light
above them this shark is virtually invisible. However, being invisible isn’t
enough to be classified as a ninja, this shark also has an extremely sensitive
enlarged eye and ampullae of lorenzini to help detect movement of prey and make
it a very effective predator of the deep that makes it stand out from all the
rest.
References
Eschmeyer, W.N. &
Fricke, R. (Eds.) (2015) Catalog of Fishes Electronic version accessed
April. 2, 2016.
Vasquez, V.E., Ebert, D.A., and Long, D.J. (2015) Etmopterus benchleyi n. sp., a new lanternshark (Squaliformes:Etmopteridae) from the central eastern Pacific Ocean. Journal of the Ocean Science Foundation 17 Electronic version accessed April. 2, 2016
Denton, H., Widder,
C. (1985) The Roles of Filters in the Photophores of Oceanic Animals and their Relation to Vision in the Oceanic Environment. Proceedings of the Royal Society B Biological Sciences.
Neiva, J., Coelho, R., and Erzini, K.
(2006) Feeding habits of the velvet belly
lanternshark
Etmopterus
spinax (Chondrichthyes: Etmopteridae) off the Algarve, southern Portugal. Journal of the Marine Biological Association, UK. 86:835-841
Wueringer, B., Peverell, S.C.,
Seymour, J., Squire, L. Jr., Kajiura, S. M., and Collin, S.P. (2011) Sensory systems in sawfish. 1. The ampullae of Lorenzini.
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