How octopuses use and recruit additional arms to find and manipulate visually hidden items

Area of Science:

• Marine Biology
• Animal Behavior
• Neuroscience

Background:

• Shallow-water benthic octopuses rely on tactile sensing via sucker chemotactile receptors.
• The coordination of multiple arms for sensing and manipulation in octopuses is not well understood.

Purpose of the Study:

• To quantify how octopuses use and recruit their arms during foraging in a visually occluded environment.
• To investigate octopus arm coordination strategies for sensing and manipulation.

Main Methods:

• Developed a behavioral assay using natural foraging behavior.
• Presented Octopus bimaculoides with opaque rock domes containing hidden items.
• Video recorded 2327 arm actions and 394 coordinated arm recruitments across 117 trials.

Main Results:

• Octopuses most frequently recruited the nearest-neighboring arm (44%) during manipulation.
• Common recruitment patterns included sequential nearest-neighbor recruitment.
• All eight arms were used with similar frequency, with three to five arms engaged simultaneously.

Conclusions:

• Octopuses demonstrate significant flexibility and functionality in using all eight arms equally.
• Findings inform research on octopus arm neuroanatomy and the design of soft robotic arms.