An inter-specific behavioural association between a highfin grouper (Epinephelus maculatus) and a reef octopus (Octopus cyanea)

Groupers and reef octopus are economically and ecologically important predators on Indo-Pacific coral reefs and known as solitary hunters. Here we describe a highly unique and unusual observation of a behavioural non-random association between the highfin grouper (Epinephelus maculatus) and the reef octopus (Octopus cyanea) in the Great Barrier Reef. Such an observation is highly novel given that the association crosses both the phyla and the invertebrate to vertebrate divide. The present study hypothesizes that the association is non-random and potentially the result of cooperative hunting but as such this requires further evidence and testing.