Adaptations for scotopic vision in the lemon shark (Negaprion brevirostris)

✍ Scribed by Cohen, Joel L.

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 751 KB
• Volume: 256
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1402560511

✦ Synopsis

The visual pigments of teleost fishes are based upon either vitamin A, or vitamin A,. The absorption spectra of these pigments provide a great enough range for fish to successfully inhabit a variety of photic environments. Elasmobranchs on the other hand, live in the same photic habitats as teleost fish, but have been found to possess visual pigments based only upon vitamin A,. The action spectrum for the dark adapted juvenile lemon shark has absorption maxima around 520 nm. This does not match the absorption spectra for the visual pigment extracted from the adult lemon shark, which is a rhodopsin, vitamin A,-based visual pigment with peak absorption at 501 nm. This mismatch has been resolved with the finding that the visual pigment of the juvenile lemon shark is a porphyropsin, vitamin A,-based visual pigment with maximum absorption a t 522 nm. There thus seems to be a developmental change from a porphyropsin to a rhodopsin system with an accompanying change in the point of maximum absorption. This can be explained by the differences in the habitats of the juvenile vs. adult animals. This also suggests that other elasmobranchs may possess vitamin A,-based visual pigments.