Octopuses Exhibit Body Ownership Illusion Similar to Humans

In a groundbreaking study, researchers from the University of the Ryukyus in Japan have discovered that octopuses can be deceived into thinking a fake arm is a part of their own body, demonstrating a complex understanding of body ownership similar to that observed in humans. The findings, published on July 28, 2025, in the journal *Current Biology*, reveal intricate sensory processes in these cephalopods, which possess a unique nervous system that operates independently from their central brain.

During the experiments led by animal behavior scientists Sumire Kawashima and Yuzuru Ikeda, plain-body night octopuses (*Callistoctopus aspilosomatis*) were placed in a controlled tank environment. Researchers utilized a method akin to the classic rubber hand illusion, where one octopus arm was concealed behind a screen while a soft gel fake arm was presented in front of it. As both limbs were stroked simultaneously, researchers pinched the fake arm, resulting in the octopuses exhibiting defensive behaviors—swimming away or changing colors—indicating they perceived an attack on their limb.

Dr. Kawashima stated, "Our findings suggest that, like humans, octopuses have a multisensory representation of their body." This revelation indicates that octopuses, with their approximately 500 million neurons distributed throughout their arms, can integrate visual cues with tactile sensations, allowing them to adopt ownership of the artificial limb. This response showcases not only their complex cognitive abilities but also highlights the evolutionary parallels between cephalopods and mammals in terms of sensory perception and body awareness.

The study builds upon previous research on body ownership illusions documented in species such as monkeys and mice. According to Dr. Yuzuru Ikeda, "These results suggest that the basic perceptual rules that determine body ownership in octopuses are similar to those of mammals. This may provide vital insights into the evolution of body representation across different species."

This phenomenon is particularly fascinating given the octopus's ability to control its arms independently from its central nervous system. Each arm can perform tasks autonomously, and the creature can even 'taste' through its suckers, underscoring the advanced functionality of its limbs. Researchers believe that the octopus's visual processing capabilities allow it to prioritize visual information over other sensory inputs, which facilitates the illusion of ownership over a limb that does not belong to it.

The implications of this research extend beyond understanding cephalopod behavior; it raises important questions regarding the nature of consciousness and body ownership in sentient beings. As Dr. Kawashima notes, the findings may serve as a significant model for studying the evolutionary development of body perception in animals with complex nervous systems.

As scientific inquiry into cephalopod cognition and perception continues, future research may explore the broader implications of these findings on our understanding of intelligence and sensory integration in non-mammalian species. Understanding how different species perceive their bodies offers profound insights into the evolutionary adaptations that shape cognitive functions in the animal kingdom, with potential applications in neurological research and artificial intelligence development.