Feel the Light: Sight-independent Negative Phototactic Response in octopus Arms
Open accessAbstract
Controlling the octopus's flexible hyper-redundant body is a challenging task. It is assumed that the octopus has poor proprioception which has driven the development of unique mechanisms for efficient body control. Here we report on such a mechanism: a phototactic response of extraocular photoreception. Extraocular photoreception has been observed in many and diverse species. Previous research on cephalopods revealed that increased illumination on their skin evokes chromatophore expansion. Recently, the mechanism was investigated and has been termed 'light-activated chromatophore expansion' (LACE). In this work we show that in response to illumination, the arm tip reacts in a reflex-like manner, folding in and moving away from the light beam. We performed a set of behavioral experiments and surgical manipulations to elucidate and characterize this phototactic response. We found that in contrast to the local activation and control of LACE, the phototactic response is mediated by the brain, although it is expressed in a reflex-like pattern. Our research results and observations led us to propose that the phototaxis is a means for protecting the arms in an instinctive manner from potential daytime predators such as fish and crabs, that could identify the worm-like tips as food. Indeed, observations of the octopuses revealed that their arm tips are folded in during the daytime, whereas at night they are extended. Thus, the phototactic response might compensate for the octopus's poor proprioception by keeping their arms folded in illuminated areas, without the need to be aware of their state.
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Arm tips reflexively withdraw from light, a response likely mediated by the brain but acting independently of visual feedback.
“Katz et al. (2021) found that arm tips reflexively withdraw from light, a response which is likely mediated by the brain but acts independently of visual feedback.”
From Lessons for Robotics From the Control Architecture of the Octopus (2022) · cites this paper as Katz et al., 2021
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- Authors
- Katz, I., Shomrat, T., & Nesher, N.
- Affiliations
- Ruppin Academic Center (IL)
- Corresponding author
- Shomrat, Tal
- ORCID
- Shomrat, Tal
- Venue
- Journal of Experimental Biology
- Publisher
- The Company of Biologists
- Published
- 2021-03-01
- Volume
- 224
- Issue
- 5
- ISSN
- 0022-0949 (ISSN-L)
- 1477-9145
- OpenAlex
- W3129037904
- Cited by
- 16
- References
- 34
- Citations by year
- 2025: 5 · 2024: 1 · 2023: 3 · 2022: 4 · 2021: 3
- FWCI
- 2.08
- Type
- journal article
- Language
- en
- Open access
- hybrid
- doi.org
- Licence
- public-domain
- www.biologists.com/user-licence-1-1/ (vor)
- Locations
- Journal of Experimental Biology (publishedVersion, public-domain)
- PubMed (publishedVersion)
- Funders
- Israel Science Foundation (1767/17)
- Topics
- Life Sciences › Agricultural and Biological Sciences › Ecology, Evolution, Behavior and Systematics › Cephalopods and Marine Biology
- Physical Sciences › Earth and Planetary Sciences › Paleontology › Marine Invertebrate Physiology and Ecology
- Physical Sciences › Earth and Planetary Sciences › Oceanography › Marine Biology and Ecology Research
- Keywords
- octopus arm, phototaxis, extraocular photoreception, chromatophores, proprioception, arm folding, cephalopod behavior, predator avoidance, body control
- MeSH terms
- Phototaxis, Animals, Arm, Emotions, Light, Reflex, Octopodiformes
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