Seventeen Metres Deep in Jervis Bay: Octopus Actions Revealed
In the serene depths of Jervis Bay, an unusual spectacle occurs, offering a unique insight into the habits of the melancholic octopus. These cephalopods are seen engaging in a direct exchange of materials, including mud, shells, and at times seaweed, via a series of intentional throws. Over a span of 21 hours of recordings obtained from stationary GoPro cameras in January 2015, researchers documented nearly 102 throws, with 17 successfully hitting another octopus.
This behavior was initially outlined in a publication in PLOS ONE by Peter Godfrey-Smith and his research team from the University of Sydney. It represents the inaugural formal recognition of octopuses participating in targeted throwing actions. The dynamics of these throws are captivating, considering the lack of a conventional “throwing arm” in octopuses.
The octopus employs its distinctive physiology to execute these throws. Materials are gathered with the arms and retained against the webbed skin that links them. By swinging its siphon—a tailored funnel used for both breathing and movement—under the web and unleashing a strong jet of water, the octopus forwards the collected debris. The arms direct the aim while the siphon generates the required force, enabling different throw distances based on the intensity of the expulsion.
Mainly, these throws seem to be associated with routine tasks like housekeeping. Approximately a third takes place during den cleaning, while 8 percent relate to discarding meal remnants. However, over half occur after encounters with nearby octopuses—whether due to conflict, mating attempts, or exploratory gestures. Females chiefly lead this behavior, executing 90 of the 102 recorded throws, with two specific females responsible for the majority of these actions.
Notably, this throwing behavior transcends interactions with one another. Equipment, such as a nearby camera, also garners attention, receiving throws that occasionally hit the tripod.
The intentionality behind the throws is a subject of fascination. As per Godfrey-Smith, some actions are likely deliberate, underscored by the accuracy and forcefulness of throws during encounters when compared to those for den upkeep. The connection between color alteration—a sign of aggression—and throw force, along with the variations in arm positioning to change throw trajectories, indicates a level of aim and purpose. Throws performed by arms other than the leading pair exhibit a significantly higher success rate.
While the question of intent remains under investigation, these discoveries stimulate conversations on animal behavior, provisionally placing octopuses among species that aim at others. Comparatively similar behaviors have mainly been noted in social mammals like chimpanzees and dolphins. Nonetheless, additional studies are essential to thoroughly comprehend the consequences and breadth of this behavior.
An intriguing documented instance featured a female octopus consistently hurling silt at a persistent male suitor. Demonstrating flexible behavior, the male adapted to anticipate and evade the throws, with initial reflexes evolving into a proactive response.
This phenomenon of intraspecific projectile throwing among octopuses, although still relatively uncommon outside of densely populated scenarios, aligns with analogous behaviors in other species, mirroring social dynamics similar to those seen in particular primates. The concentrated gathering of octopuses in Jervis Bay is attributed to the plentiful food supply and limited adequate habitat, promoting these extraordinary interactions.
Prospective efforts will likely focus on capturing octopus social structures in diverse settings, motivating scientists to respect observation distances to broaden this captivating field of marine animal behavior study.