Behavioral and chromatic dynamics describing mating interactions of the south American octopus Robsonella fontaniana (Cephalopoda: Octopodidae)

Abstract

Cephalopods are characterized by a substantial behavioral flexibility during reproductive interactions; however, for octopods rather few studies have provided empirical information on the mechanisms operating during male–male and male–female encounters. Using the small south American octopus Robsonella fontaniana (∼270 mm total length, ∼70 mm mantle length), we evaluated the mating behavior based on octopuses from central Chile. Eighteen male–female and five male–male interactions were characterized in laboratory using ethograms divided into precopulatory and copulatory stages. Although subjects’ interactions occurred in both treatments, extended mating periods (81–196 min) were only observed in the male–female trials, and specifically, in those involving larger octopuses (39% of the interactions; > 43 mm mantle length). During the precopulatory stage (4–20 min), different behavioral displays were evidenced in 57% of these male–female interactions, including: contact, exhibition of chromatic displays, swimming, and mounting. Larger pairs had longer copulation times, with a maximum of ∼200 min in octopuses of 50 mm mantle length. The observed mating in adult male–female pairs and the practically null interaction between juveniles suggest that a maturity-conditional reproductive behavior (∼43 mm mantle length; ∼38 gr), could be one of the mechanisms modulating mating interactions of R. fontaniana in the wild, potentially influencing aspects such as mate guarding behavior, possible sperm removal or sperm loading.