The possible selective forces influencing behavioural differences between females and males were less clear. However, the greater difference in the R3 arm performance, which is the hectocotylus in males, was an interesting observation, which could be explained as a preservation and defence mechanism of the reproductively modified arm because an injury might preclude any future mating. Indeed, males of octopus (Abdopus aculeatus) were observed holding hectocotylus close to the body when foraging, and it is possible to assume that males would extend the R3 only for purpose of mating ( Huffard et al., 2008).