Octopus mimicking its follower reef fish

Octopus mimicking its follower reef fish

Journal of Natural History. 2009. Vol. 43. No. 3 & 4. 185-190.
J. P. Krajewski (ab), R. M. Bonaldo (ac), C. Sazima(d), I. Sazima(e)
(a) School of Marine and Tropical Biology, James Cook University
(b) Departamento de Zoologia e Ps-Graduao em Ecologia, Universidade Estadual de Campinas
(c) Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University
(d) Departamento de Parasitologia, Universidade Estadual de Campinas, Campinas
(e) Museu de Zoologia, Universidade Estadual de Campinas, Campinas

We describe a possible example of social mimicry between Octopus insularis and the small grouper Cephalopholis fulva, which frequently associate during foraging at Fernando de Noronha Archipelago, Brazil. The octopus, when swimming backwards, jet-propelled, becomes similar in colour and shape to accompanying C. fulva individuals and is therefore less conspicuous within the fish group. We regard this as an instance of social mimicry, a form of protection against visually-oriented predators in which different species similar in shape and colour mingle for the advantage of grouping. Even when swimming backwards alone, O. insularis may become similar to foraging C. fulva individuals, another putatively protective behaviour. We suggest that the feeding association commonly found between O. insularis and C. fulva minimized the evolutionary costs for the origin of mimicking by the octopus.

Keywords: social mimicry; Octopus insularis; Cephalopholis fulva; foraging association; Fernando de Noronha Archipelago