By Chris Deziel Updated Mar 24, 2022
The suction cups on an octopus’s arms are universally referred to as suckers. Each sucker’s inner surface, known as the infundibulum, surrounds a central cavity called the acetabulum. Their powerful grip results from a combination of suction, muscular control, and microscopic grooves.
In cephalopod biology, the term sucker is the standard designation for the adhesive pads that adorn each arm. The most visible portion is the infundibulum, a soft, flexible disc edged by a mucous‑rich epithelium. Inside lies the round acetabulum, a cavity that creates the vacuum when the sucker seals against a surface.
Each sucker is anchored to the arm by a muscular base capable of rotating in any direction and extending up to twice its resting length. The muscles within the acetabulum and infundibulum provide tactile feedback, allowing the octopus to “walk” objects along its arms with remarkable precision.
The effectiveness of an octopus’s grip stems from more than just a cup‑like shape. Microscopic analysis reveals concentric grooves in the infundibulum and a highly elastic composition that conforms to irregular textures, enhancing the seal. Radial muscle fibers from the center to the rim further reinforce the suction, granting these animals the ability to lift and manipulate objects that weigh many times their own body mass.
Octopuses exhibit several features that set them apart from mammals, such as three hearts and dynamic color change for camouflage and communication. A key physiological distinction is the blue hue of their blood. While human blood relies on iron‑rich hemoglobin, octopus hemolymph contains copper‑based hemocyanin, which transports oxygen more efficiently in cold, low‑oxygen environments. However, this copper chemistry makes their blood highly sensitive to pH changes, rendering octopuses vulnerable to ocean acidification.
