Octopuses are fascinating marine creatures. While a common misconception is that they can breathe air, they do not possess lungs and are unable to breathe atmospheric air. Fully adapted for life underwater, they rely on specialized organs to extract dissolved oxygen from their watery environment.
How Octopuses Breathe Underwater
Octopuses primarily breathe through gills, located within their mantle cavity. Water is drawn into this muscular cavity, then circulated over the gills. These gills are rich in tiny blood vessels called capillaries, which absorb dissolved oxygen from the water.
Two branchial hearts support gas exchange, pumping blood through the gills. After oxygen is extracted, deoxygenated water is expelled from the mantle cavity through a tube-like siphon. This expulsion also aids in jet propulsion, a mode of movement for octopuses. Beyond their gills, octopuses can also absorb some oxygen through their skin, a process known as cutaneous respiration, which can contribute to their oxygen intake while at rest.
Why Gills Don’t Function in Air
An octopus’s gills cannot function effectively in air. The delicate filaments require the buoyancy of water to remain spread out, providing a large surface area for gas exchange. When an octopus is removed from water, these structures collapse and stick together due to surface tension, drastically reducing the surface area for oxygen absorption.
The gills also need to remain moist for gas diffusion. In air, they quickly dry out, inhibiting oxygen extraction. While an octopus can survive for short periods out of water by absorbing some oxygen through its skin, this method is far less efficient than gill respiration and not sustainable for long durations. Prolonged exposure to air can lead to gill damage and suffocation.
Octopus Life in an Aquatic Environment
An octopus’s physiology is adapted for its aquatic existence. Their soft, boneless bodies, except for a hard beak, allow them to squeeze through small spaces and crevices. This flexibility is crucial for navigating complex environments, escaping predators, and ambushing prey.
Movement through water is achieved through jet propulsion, where water is expelled from the mantle through the siphon, propelling the octopus. Octopuses also demonstrate remarkable camouflage abilities, changing their skin color and texture to blend with their surroundings, aiding hunting and evading detection. These adaptations highlight their reliance on their marine world.