Body size determines eyespot size and presence in coral reef fishes

Hemingson, Christopher R., Cowman, Peter F., and Bellwood, David R. (2020) Body size determines eyespot size and presence in coral reef fishes. Ecology and Evolution, 10 (15). pp. 8144-8152.

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Numerous organisms display conspicuous eyespots. These eye-like patterns have been shown to effectively reduce predation by either deflecting strikes away from nonvital organs or by intimidating potential predators. While investigated extensively in terrestrial systems, determining what factors shape eyespot form in colorful coral reef fishes remains less well known. Using a broadscale approach we ask: How does the size of the eyespot relate to the actual eye, and at what size during ontogeny are eyespots acquired or lost? We utilized publicly available images to generate a dataset of 167 eyespot-bearing reef fish species. We measured multiple features relating to the size of the fish, its eye, and the size of its eyespot. In reef fishes, the area of the eyespot closely matches that of the real eye; however, the eyespots "pupil" is nearly four times larger than the real pupil. Eyespots appear at about 20 mm standard length. However, there is a marked decrease in the presence of eyespots in fishes above 48 mm standard length; a size which is tightly correlated with significant decreases in documented mortality rates. Above 75-85 mm, the cost of eyespots appears to outweigh their benefit. Our results identify a "size window" for eyespots in coral reef fishes, which suggests that eyespot use is strictly body size-dependent within this group.

Item ID: 64461
Item Type: Article (Research - C1)
ISSN: 2045-7758
Keywords: body size, constraints, coral reef fishes, eyes, eyespots, ocellus
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Copyright Information: © 2020 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
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A version of this publication was included as Chapter 3 of the following PhD thesis: Hemingson, Christopher (2021) The colours of coral reef fishes. PhD thesis, James Cook University, which is available Open Access in ResearchOnline@JCU. Please see the Related URLs for access.

Funders: Australian Research Council (ARC)
Projects and Grants: ARC Grant Number: CE140100020, ARC Grant Number: FL190100062
Date Deposited: 23 Sep 2020 07:41
FoR Codes: 31 BIOLOGICAL SCIENCES > 3103 Ecology > 310305 Marine and estuarine ecology (incl. marine ichthyology) @ 100%
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