User:Jewellha/Malacosteus niger

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.

Red Light Bioluminescence
Other deep-sea fish capable of detecting far-red bioluminescence, including Aristostomias and Pachystomias are able to do so using visual pigments. M. niger lacks these same long-wave pigments, and instead increases its sensitivity to red light using a chlorophyll-derived photosensitizer.