On the metamorphosis of the visual pigments of Anguilla anguilla (L.)

• Published in: Journal of the Marine Biological Association of the United Kingdom
• Main Authors: Carlisle, D. B., Denton, E. J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1959
• Subjects: Aquatic Science; Anguilla anguilla
• Online Access: http://dx.doi.org/10.1017/s0025315400015629; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0025315400015629

The retinae of all the species of deep-sea fish which have been studied have been shown to contain golden coloured pigments, chrysopsins, which are especially suited to the light found in their natural environment (Denton & Warren, 1957; Munz, 1958). Amongst fish caught in shallow coastal waters this characteristic colour of retinal pigment is found only in the conger eel Conger conger (by Denton & Walker, 1958), and amongst freshwater fish only in the silver eel Anguilla anguilla (by Carlisle & Denton, 1957, referred to by Denton & Warren, 1957). Both these fish are species of Apodes, a group of which the vast majority of species are deep-water forms. Both species, more- over, begin their life in the deep sea and return to it again when mature to spawn and may therefore, in one sense, be regarded as deep-sea fish. Since immature conger eels in shallow coastal waters already have a retinal pigment characteristic of a deep-sea fish, it seems very unlikely that on returning to deep water they would change away from the deep-sea form which they already possess. It is probable therefore that the conger retains a deep-sea form of retinal pigment throughout the whole of its life.