Breaking Boundaries: First Observation of Intertidal Emergence During Mating in Octopuses

Hidde Juijn, Miguel Cabanellas-Reboredo, Ángel F. González, Jorge Hernández-Urcera, 2026.Breaking Boundaries: First Observation of Intertidal Emergence During Mating in Octopuses. Ecology and Evolution. Volume 16. Issue 4Apr 2026. https://doi.org/10.1002/ece3.73503

Abstract:Reproductive behaviour in octopuses is diverse, yet field observations remain limited for nocturnal species such as Callistoctopus macropus. We report the first documented case of intertidal emergence during copulation in an octopus. During a night dive inIbiza, a mating pair of C. macropus moved gradually from shallow water onto the rocky shore while remaining physically con-nected. Once emerged, the female showed a putative escape behaviour, anchoring to nearby rocks, while the male persisted andcounter-anchored, resulting in a prolonged struggle with both individuals partially exposed for ~20 min before re-submerging.This behaviour is unprecedented and suggests that intertidal emergence may function as an extreme female resistance tactic within the context of sexual conflict. These observations expand the known behavioural repertoire of octopuses and highlight the need for further study of social dynamics in natural settings.

Keywords:Callistoctopus macropus,in situ observation,intertidal emergence,reproductive behaviour,sexual conflict.