Wild Wunderpus photogenicus and Octopus cyanea employ asphyxiating ‘constricting’ in interactions with other octopuses

Abstract

Aggressive constricting including asphyxiation was observed in wild octopuses (Octopus cyanea Gray, 1849, and Wunderpus photogenicus Hochberg, Norman & Finn, 2006). The distal portion of a dorsolateral arm formed a loop around the mantle of another octopus, in at least one case preventing the flow of water into the mantle, over the gills and out of the funnel. Constricting also may have prevented the subordinate individual from releasing ink, a possible irritant and predator attractant. A female O. cyanea used constricting as a form of fatal aggression to asphyxiate a male as part of apparent sexual cannibalism. This female killed a male with which she was mating using the ‘distance’ position. Constriction allowed a W. photogenicus to win during physical interspecific aggression with a close relative, Thaumoctopus mimicus Norman & Hochberg, 2005. This action took place near an immediately available food source and interrupted foraging by T. mimicus, providing possible evidence of interference competition among closely related sympatric cephalopod species in the wild.

Keywords:

• cephalopod behaviour
• interference competition
• ecology
• foraging
• sibling species
• interspecific aggression
• soft sediment
• charismatic species
• hydrostatic skeleton
• sexual cannibalism

Acknowledgements

MB thanks Crystal Blue Resort (Anilao, Philippines) and ‘Kuya’ (brother) Edgar Atienza for their dedication and enthusiasm for finding animals like Wunderpus and the Mimic, and understanding their natural history. CLH thanks Laure Katz for alerting attention to the mating Octopus cyanea described here, along with dive buddies Rudi Dimara, Andi Fauzan, Muhammad Lazuardi, and Defy Pada. We both thank the editor and two anonymous reviewers for their insightful comments that greatly improved this manuscript.