Title

Visual Acuity in Pelagic Fishes and Mollusks

Document Type

Article

Publication Date

11-2013

Publication Title

Vision Research

Keywords

Eye, Lens, Optics, Point spread function, Contrast, Deep-sea

ISSN

0042-6989

Volume

92

First Page

1

Last Page

9

Abstract

In the sea, visual scenes change dramatically with depth. At shallow and moderate depths (<1000 m), there is enough light for animals to see the surfaces and shapes of prey, predators, and conspecifics. This changes below 1000 m, where no downwelling daylight remains and the only source of light is bioluminescence. These different visual scenes require different visual adaptations and eye morphologies. In this study we investigate how the optical characteristics of animal lenses correlate with depth and ecology. We measured the radius, focal length, and optical quality of the lenses of pelagic fishes, cephalopods, and a gastropod using a custom-built apparatus. The hatchetfishes (Argyropelecus aculeatus and Sternoptyx diaphana) and the barrel-eye (Opisthoproctus soleatus) were found to have the best lenses, which may allow them to break the counterillumination camouflage of their prey. The heteropod lens had unidirectional aberrations that matched its ribbon-shaped retina. We also found that lens angular resolution increased with depth. Due to a similar trend in the angular separation between adjacent ganglion cells in the retinas of fishes, the perceived visual contrast at the retinal cutoff frequency was constant with depth. The increase in acuity with depth allows the predators to focus all the available light bioluminescent prey animals emit and detect their next meal.

Comments

©2013 Elsevier B.V. All rights reserved.

Additional Comments

Office of Naval Research grant #: N00014-09-1-1053

ORCID ID

0000-0002-5280-7071

DOI

10.1016/j.visres.2013.08.007

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Peer Reviewed

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