Short-wave absorbing pigments in the ocular lenses of deep-sea teleosts

Abstract

This study describes the spectral characteristics between 250 and 700 nm of lenses from 71 species of deep-sea teleost. The majority of these did not contain detectable amounts of short-wave absorbing pigment and transmitted all longer wavelengths to the same extent before cutting off smoothly and rapidly in the near-UV (50% transmission 310–348 nm). The lenses of 15 species, however, contained significant amounts of short-wave absorbing pigment. The majority of these lenticular pigments had smooth ‘bell-shaped’ absorbance spectra with a single peak in the near-UV. Such ‘simple’ pigments were extracted from four species (λmax: 360·8 nm, 36·50 nm, 395·7 nm, 324·8 nm) and detected in a further eight species, although insufficient material was available to allow their extraction from the latter group.The absorbance profiles of lenses from another three species were more complex, suggesting the presence of one and two carotenoid-like pigments respectively in the lenses ofArgyropelecus sladeniandA. affinis,and two as yet unidentified pigments in the lenses ofMalacosteus niger.This brings the total of short-wave absorbing pigments so far described in the lenses of deep-sea fish to at least eleven. InArgyropelecusspp. the pigmentation was most pronounced in the lens cortex, while inMalacosteus nigerit was restricted to the lens core. In all other species the pigment appeared freely diffusible throughout the lens. Several species showed an increase in the degree of lenticular pigmentation in older animals and two(Argyropelecus affinisandMalacosteus niger)demonstrated age-related changes in the relative concentrations of two different pigments within the lens.