A detailed investigation of the visual system and visual ecology of the Barrier Reef anemonefish, Amphiprion akindynos

Sara M Stieb,Karen L Carleton,Wen-Sung Chung,Brian E Dalton,Luke A Hammond,N Justin Marshall,Fanny De Busserolles,Fabio Cortesi

doi:10.1038/s41598-019-52297-0

Abstract

Vision plays a major role in the life of most teleosts, and is assumingly well adapted to each species ecology and behaviour. Using a multidisciplinary approach, we scrutinised several aspects of the visual system and ecology of the Great Barrier Reef anemonefish, Amphiprion akindynos, including its orange with white patterning, retinal anatomy and molecular biology, its symbiosis with anemones and sequential hermaphroditism. Amphiprion akindynos possesses spectrally distinct visual pigments and opsins: one rod opsin, RH1 (498 nm), and five cone opsins, SWS1 (370 nm), SWS2B (408 nm), RH2B (498 nm), RH2A (520 nm), and LWS (554 nm). Cones were arranged in a regular mosaic with each single cone surrounded by four double cones. Double cones mainly expressed RH2B (53%) in one member and RH2A (46%) in the other, matching the prevailing light. Single cones expressed SWS1 (89%), which may serve to detect zooplankton, conspecifics and the host anemone. Moreover, a segregated small fraction of single cones coexpressed SWS1 with SWS2B (11%). This novel visual specialisation falls within the region of highest acuity and is suggested to increase the chromatic contrast of Amphiprion akindynos colour patterns, which might improve detection of conspecifics.

Highlights

Vision plays a major role in the life of most teleost fishes to enable foraging, avoidance of predators, navigation, and mate choice
We focused our study on the Barrier Reef Anemonefish, Amphiprion akindynos, a species mainly found on the Great Barrier Reef in Australia
We confirmed the repertoire of opsin genes known for A. akindynos[38], and were able to obtain the complete coding regions of SWS1, SWS2B, RH2B, RH2A, LWS, and RH1

Summary

Introduction

Vision plays a major role in the life of most teleost fishes to enable foraging, avoidance of predators, navigation, and mate choice (e.g., reviewed in[1,2,3]). Diurnal coral reef fishes that live in a very bright and colourful environment, www.nature.com/scientificreports often have acute colour vision provided by complex photoreceptor mosaics of several cone types being sensitive to a wide spectrum of light[15]. Interspecific variability in the number and connectivity of ganglion cells, and the visual acuity, often reflects the feeding behaviour of a species[10]. Intraretinal variability is often assessed by constructing topographic maps of photoreceptor and ganglion cell distribution This allows the identification of regions of high-cell densities or specialisations, which provide a higher sensitivity or acuity in a specific part of the visual field of the animal. The retinal topography usually reflects the structure of the habitat (terrain theory14,16), the behavioural ecology (e.g., feeding strategy[17], predator avoidance18), the light environment[10], and the life stage of an animal[19]

Methods

Results

Conclusion