Малакостеус нигер: Теңіздің қара жыртқышы

Species of fish
Speciesbox
| image = Manig u4. jpg
| status system = IUCN3.1
| status = LC
| status ref = It belongs to the family Stomiidae, or dragonfishes. It is among the top predators of the open mesopelagic zone. M. niger is a circumglobal species, which means that it inhabits waters ranging from the tropics to the subarctics. Not many studies have been conducted on its feeding habits, but recent research suggests that M. niger primarily feed on calanoid copepods which is a form of zooplankton. Indeed, it appears that M. niger primarily prey on zooplankton despite its apparent morphological adaptations for the consumption of relatively large prey. Its retina is made up entirely of rods and no cones, with rhodopsin/porphyropsin pairs and a single opsin bound to some of its photoreceptors, which provide visual sensitivity up to 517 541 nm (this falls within the wavelength of red light). Most deep sea fish have a single visual pigment maximally sensitive at short wavelengths, approximately matching the spectrum of both downwelling sunlight and bioluminescence. For comparison, other red light producing stomiids, such as Aristostomias and Pachystostomias, have a third pigment which allows them to perceive light up to 588 nm and 595 nm respectively. The yellow lens reduce the amount of blue light that reaches the retina and increases sensitivity to longer wavelengths, which benefits M. niger and its red bioluminescence. Yellow lens have also been identified in Echiostoma, which also produces red bioluminescence.

Malacosteus niger has one of the largest relative gapes of any fish with the lower jaw being approximately one quarter of the fishes length (Figure A). Lastly, M. nigers lacks an ethinoid membrane (no “floor” in its mouth) which allows for it to consume bigger prey species (Figure D). The postorbital photophore in this species is larger than in M. australis. It also differs in lateral photophore count, as well as in morphological characters. The maximum known length is 25.6 cm (10.1 in). Its specific epithet niger is Latin for "black".

Malacosteus niger is a circumglobal species and has a large geographic range. It can typically be found from the Arctic latitudes of 66° North and from 30° South in the Southern Hemisphere. M. niger does not leave the mesopalgic and is known to have a vertical range from 500 meters to 1000 meters. Some of its documented prey include calanoid copepods, micronekton, decapod shrimps, and other decapods.

Malacosteus niger's unique adaptation of producing red bioluminescence is only found in two other deep sea dwelling creatures, Aristostomias and Pachystomias. This rare form of bioluminescence can reach up to 700 nm in the deep sea and cannot be perceived by green and blue bioluminescent organisms, thus granting M. niger a considerable advantage while hunting for food. Malacosteus Niger has a tear drop shaped, dark brown, suborbital photophore which is used to emit red light at an emission maxima of 710 nanometers. Removal of the top brown photophore layer causes a shift of the emission spectra to shorter wavelengths of around 650 nanometers. The photophores contain red fluorescent material which is made to fluoresce via energy transfer from chemical reactions. Control of the photophore is maintained via innervation through branches of the fifth cranial nerve and this photophore. It is reported to be controlled independently of the postorbital blue photophore and has been noted to fluoresce for longer durations. The photophore is composed of a large pigmented sac containing a mass of scarlet gland cells. A thick, reflective layer lines the pigment sac, with occasional strands of reflective tissue running through the glandular core of the photophore. The outer layer is composed of large epithelial cells which merge into an inner, darker stained layer. The presumed function of this layer is to provide the brown layer through which fluorescence is filtered. The cells of the glandular core are characterized by a dense rough endoplasmic reticulum.