Multi-species co-operative hunting behaviour in a remote Indian Ocean reef system

ABSTRACT

Inter-specific hunting associations can occur across a range of marine species to facilitate prey capture through co-operative behaviour. Here we describe multiple transient cross-phyla associations between day octopus (Octopus cyanea) and three fish species, including peacock grouper (Cephalopholis argus), brown-marbled grouper (Epinephelus fuscoguttatus), and gold-saddle goatfish (Parupeneus cyclostomus), in the isolated reef system of the Chagos archipelago. Observations of such hunting associations are rare, and no similar observations have been recorded for this region. The remoteness of this study site may provide some explanation for these multiple sightings, allowing natural behaviours to occur undisturbed. However, given no previous sightings of such behaviour, the limitation of available food resources following two recent mass coral mortality episodes, may have necessitated the formation of these rare/novel hunting interactions. Intensified prey scarcity and increasingly degraded habitat structure following more frequent disturbance events may therefore lead to such indirect environmentally mediated behavioural responses becoming increasingly prevalent in reef-dwelling species.

KEYWORDS:

• Fish behaviour
• reefs
• octopus
• hunting
• co-operation

Acknowledgments

Funding for research was provided by the Bertarelli Foundation under grant agreement BPMS 2017-6. Thanks also to Bryan Wilson and Adrian Smith for their supervision and financial support to AR; to Andy Mogg for assistance in creating the 3D models; and to the crew of the Grampian Frontier research vessel for help during the expedition. There are no conflicts of interest and there is no financial interest or benefit that has arisen from the direct applications of this research.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

A video detailing examples of the observed interactions can be viewed at: https://youtu.be/m7Ql6CPiGPw

Additional information

Funding

This work was supported by the Fondation Bertarelli [BPMS 2017-6].