Title

Spectral Sensitivity, Luminous Sensitivity, and Temporal Resolution of the Visual Systems in Three Sympatric Temperate Coastal Shark Species

Document Type

Article

Publication Date

12-2014

Publication Title

Journal of Comparative Physiology A

Keywords

Elasmobranch, Electroretinogram, Flicker fusion frequency, Temperature, Vision

ISSN

0340-7594

Volume

200

Issue/No.

12

First Page

997

Last Page

1013

Abstract

We used electroretinography (ERG) to determine spectral and luminous sensitivities, and the temporal resolution (flicker fusion frequency, FFF) in three sympatric (but phylogenetically distant) coastal shark species: Carcharhinus plumbeus (sandbar shark), Mustelus canis (smooth dogfish), and Squalus acanthias (spiny dogfish). Spectral sensitivities were similar (range ~400–600 nm, peak sensitivity ~470 nm), with a high likelihood of rod/cone dichromacy enhancing contrast discrimination. Spiny dogfish were significantly less light sensitive than the other species, whereas their FFF was ~19 Hz at maximum intensities; a value equal to that of sandbar shark and significantly above that of smooth dogfish (~9–12 Hz). This occurred even though experiments on spiny dogfish were conducted at 12 versus 25 °C and 20 °C for experiments on sandbar shark and smooth dogfish, respectively. Although spiny dogfish have a rod-dominated retina (rod:cone ratio 50:1), their visual system appears to have evolved for a relatively high temporal resolution (i.e., high FFF) through a short integration time, with the requisite concomitant reduction in luminous sensitivity. Our results suggest adaptive plasticity in the temporal resolution of elasmobranch visual systems which reflects the importance of the ability to track moving objects such as mates, predators, or prey.

Comments

©Springer-Verlag Berlin Heidelberg (outside the USA) 2014

DOI

10.1007/s00359-014-0950-y

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Peer Reviewed

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