Octopus use smell to locate prey

Jenn Hoskins
10th October, 2025

Octopus use smell to locate prey

To track the octopus's movements in the dark, scientists used software to pinpoint its eyes, allowing them to determine the direction the octopus was facing (blue arrow) versus the direction it was actually moving (orange arrow).

Image adapted from: Weertman et al. / CC BY (Source)

Key Findings

  • Octopuses in Washington State were shown to intentionally navigate towards food by detecting and following chemical plumes in a dark tank
  • While tracking the plume, octopuses exhibited odor-gated rheotaxis, pausing and zig-zagging against the water current to pinpoint the food source
  • The study suggests octopuses primarily use suckers on their arms to detect chemical signals, indicated by fast, reactive lunging motions and a lack of full-body orientation towards the food
Chemosensory plume-guided navigation – following a chemical signal to its origin – is a fundamental behavior observed across the animal kingdom, particularly useful for finding resources when vision is limited. Researchers at the University of Washington[1], alongside collaborators from Alaska Pacific University, Elmhurst University, and the University of California Irvine, have now directly observed and documented this behavior in octopuses for the first time in a laboratory setting. This research addresses a long-standing question about how these intelligent invertebrates locate food, given their often-reported tendency to forage ‘blindly’ in complex environments. The study focused on whether octopuses could intentionally navigate towards a food source by detecting and following a chemical plume – essentially, the scent trail released by the food dissolving in water. To test this, octopuses were placed in a tank with a controlled flow of water, and food (crab and shrimp) was introduced at one end, creating a plume that drifted downstream. The experiments were conducted in complete darkness to eliminate vision as a factor. The results strongly indicated that octopuses were able to use the chemical plume to find the food. In a three-station discrimination task, the octopuses consistently moved upstream, towards the station containing the food source, demonstrating a clear preference. This supports the idea that they weren't simply randomly exploring, but actively searching based on the scent. Further investigation revealed specific behaviors when octopuses were seeking a single food target. They didn’t just move in a straight line; they exhibited a pattern called odor-gated rheotaxis. Rheotaxis is a common strategy in many animals where they adjust their movement based on the water current and the presence of a chemical signal. In this case, the octopuses paused, made “switchbacks” (zig-zagging against the current), and made redirections across the flow – all indicative of actively tracking the plume to pinpoint the source. Interestingly, the researchers also observed fast, reactive lunging motions as the octopuses approached the baited station. This, combined with the fact that the octopuses didn't orient their entire body towards the food source (as you’d expect if they were relying on bilateral olfactory organs), led the team to hypothesize that the suckers on their arms are the primary organs responsible for detecting the chemical signals. This is a significant finding, as it suggests a distributed sensory system is at play. These findings build upon earlier work highlighting the variability in olfactory system size across vertebrates[2]. That study proposed that the olfactory bulb’s size isn’t simply related to an animal’s overall brain size, but rather to the demands of navigation. The octopus study offers a compelling example of this principle in action – the octopus's foraging behavior appears to rely heavily on olfactory navigation, potentially explaining the complexity of their chemosensory system. Previous research has also emphasized the importance of olfaction in search behavior across a wide range of animals, from microorganisms to rodents[3]. While the mechanisms behind olfactory search are often poorly understood, the octopus study provides valuable insights into how larger animals might solve the challenges of turbulent airflow and efficiently sample the environment for olfactory information. Notably, the study corroborates findings from research on octopus foraging habits, which showed they frequently explore crevices blindly and rely on contact chemoreception to discriminate between potential prey[4]. The current work expands on this by demonstrating that octopuses can not only detect prey through contact chemoreception, but also use a more distant chemical signal – the plume – to guide their overall search strategy. This suggests a multi-modal sensing approach, where contact chemoreception refines the search once the octopus is in close proximity to a potential food source, following an initial plume-guided navigation.

WildlifeEcologyMarine Biology

References

Main Study

1) Octopus track chemosensory plumes to find food

Published 8th October, 2025

https://doi.org/10.1371/journal.pone.0330262

Related Studies

2) From chemotaxis to the cognitive map: the function of olfaction.

https://doi.org/10.1073/pnas.1201880109

3) Algorithms for Olfactory Search across Species.

https://doi.org/10.1523/JNEUROSCI.1668-18.2018

4) Contact chemoreception in multi-modal sensing of prey by Octopus.

https://doi.org/10.1007/s00359-022-01549-y


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