The Visual Pigments of Some Deep-Sea Elasmobranchs

Abstract

The deep-sea teleosts have golden-coloured retinae, the photosensitive pigments of which absorb maximally at wavelengths close to the band of wavelengths around 475 mfL to which the oceans are most transparent (Denton & . Warren, 1956, 1957Munz, 1957 Munz, , 1958aWald, Brown & Brown, 1957). In this they differ from freshwater fish, which usually have purple-coloured retinae absorbing maximally at wavelengths around 525 mfL, and marine coastal fish, which usually, but not always, have reddish-coloured retinae absorbing maximally at wavelengths close to 500mfL (Wald, 1945-46;Dartnall, 1952; Munz, 1958b). This communication extends these studies to include three species of deep-sea elasmobranchs, using the classical method of making digitonin extracts.With a little experience it is easy to estimate from the colours of freshly dissected retinae of dark-adapted animals the approximate wavelengths of maximum absorption of their retinal pigments. When interesting animals have been available on occasions when we could not make a detailed study of the retinal pigments, we have, therefore, examined their retinae also, comparing them with retinae from animals such as the frog and the conger eel, whose retinae have been very well studied. Here we describe observations of this kind made on the salmon and the Moray eel. MATERIALSThe deep-sea sharks, Centroscymnus coelolepis Bocage & Capello, Centrophorus squamosus Bonnaterre and Deania calcea Lowe, were caught at a depth of 1,150 m at 47°41'5' N., 7°36' W. They were caught at night in May using a deep-sea line. The hake, Merluccius merluccius (L.), were caught at night by trawl 21 miles south of the Wolf rock in the English channel. Moray eels, Muraena helena L., were supplied by fishermen working off Monaco. METHODSPreparation of retinae. The sharks and hake were caught at night and kept alive in a darkened sea-water tank for a few hours until their eyes were dissected. Moray eels were dark-adapted in a tank of sea water for several hours before their eyes were removed.'.

Retinal specialisations in the dogfish <i>Centroscymnus coelolepis</i> from the Mediterranean deep-sea

“…), as well as near South Africa (Lycoteuthis lorigera) and in the Atlantic (Taningia danae) (Clarke and Merrett, 1972;Carrassón et al, 1992;Ebert et al, 1992), confirm their preference for this type of prey. The spectral emissions of H. dispar photophores at 474 nm (Dilly and Herring, 1978) and of T. danae at 475-480 nm (Herring et al, 1992) are well matched to the maximum absorption of the C. coelolepis visual pigment at 472 nm (Denton and Shaw, 1963). This overlap between the light emission of the prey and the maximum absorption of the visual pigment of the predator strongly suggests that bioluminescence is an important signal for C. coelolepis prey detection.…”

“…Nevertheless, vision of deepsea sharks is only partially understood. Denton and Shaw (1963) investigated the visual pigments of some deep-sea elasmobranchs and found that C. coelolepis showed appreciable absorption at 472 nm, close to the wavelength at which the sea is most transparent. In 1991, Crescitelli (1991) found that visual pigment in the brown cat shark Apristurus brunneus, trawled from a depth of 550 m, absorbed maximally at 483 nm.…”

Spectral sensitivity of the dogfish shark (Scyliorhinus canicula)

“…Deep-sea sharks were shown to have ''chrysopsislike'' photopigments with spectral maxima at 472-484 nm (Denton and Shaw 1963); similarly. therefore to a great number of deep-sea fish species that all possess a single rhodopsin with a wavelength of maximum absorbance in the range 470-495 nm (Partridge et al 1989).…”

Retinal Morphology and Visual Specializations in Three Species of Chimaeras, the Deep-Sea R. pacifica and C. lignaria, and the Vertical Migrator C. milii (Holocephali)

“…The rod visual pigments of most deep-sea fishes contain a chromophore based on vitamin A 1 that absorbs wavelengths between 470 and 490 nm [Denton and Shaw, 1963;Beatty, 1969;Crescitelli, 1969;Partridge et al, 1989;Douglas et al, 1995;Fröhlich et al, 1995]. Although little is known about the photoreceptors in chimaerids, Vigh-Teichman et al [1990] characterized two types of rods based on immunohistochemical and ultrastructural criteria in the rabbit fish, C. monstrosa.…”