In the abyss of the Pacific Ocean, nearly 5,000 meters below the surface, an unusual scene has captivated the attention of marine biologists. A Cirrate octopus, belonging to the species Cirrothauma magnastood out for its unique method of movement among wild animals inhabiting the oceans: a unique aquatic choreography consisting of a series of graceful bounces on the seabed.
The secrets of an abyss hunter
Aboard the ship Dagon, researchers from the University of Western Australia had the privilege of observing this rare spectacle during the Trans-Pacific Transit expedition. At this depth, the darkness is total, because light can no longer penetrate that far and the pressure is overwhelming. Imagine the weight of several thousand cars pressing down on every square inch of your body. This is approximately the pressure that organisms living at this depth experience; that’s why these have evolved to be able to survive these extreme conditions : gelatinous bodies, flexible skeletons, slow metabolism, etc.
Scientists have been able to document its behavior using sophisticated underwater laboratories, specially designed to withstand deep sea conditions. These cutting-edge technologies allowed them to capture exceptionally sharp images.
Cirrothauma magna, nicknamed “ jellyhead » (jellyfish head) due to its appearance, has demonstrated remarkable adaptation to its hostile environment. A highly developed gelatinous body, very strong resistance to cold and filaments which serve to detect movements and odors in the darkness of the abyss. However, what really sets it apart from other organisms living in these depths is it’s the fact that it seems to bounce to move (see video below).
Observations carried out between 2020 and 2022 by Dr Alexey Golikov and his team at the GEOMAR Helmholtz Center for Ocean Research helped unravel the mystery of this aquatic dance. This abysmal ballet is not just a simple mode of locomotion: this is actually a very effective hunting strategy.
With each bounce, the octopus deploys its tentacles, transforming the membrane that connects them into a real capture net. This living parachute, of formidable efficiency, allows it to trap its prey every time it hits the bottom. This technique thus maximizes the capture surface while minimizing energy expenditure, a considerable advantage in an environment where resources are scarce. The researchers also noted that the height and frequency of bounces appeared to vary depending on the density of potential prey in the area.
Behavior documented since 1997
This discovery is part of a continuum of scientific observations dating back to 1997, the year when similar behaviors were documented in other species of Cirrates octopuses living at shallower depths. These previous observations, initially considered anecdotal, today take on a new dimension. They suggest an evolutionary adaptation shared by several species of abyssal cephalopods, testifying to the convergence of solutions developed by these organisms to the challenges posed by life in the great depths.
Comparative analyzes carried out by Dr Golikov’s team highlighted subtle variations in the execution of this technique depending on species and depths, illustrating the remarkable behavioral plasticity of these creatures.
While our eyes (and our finances!) are largely focused on space, Cirrothauma magna reminds us that we have only explored a tiny part of the abyss: less than 5% of the ocean floor has been mapped in detail. Each discovery, however tenuous, always enriches our understanding of these complex ecosystems. Continuing to probe the bottom of our oceans is not just a matter of intellectual curiosity; understanding them better is also giving us better ways to protect them more effectively.
- A unique Cirrate octopus uses bouncing to hunt in the abyss, capturing prey with its parachute tentacles.
- This rare behavior, observed at a depth of 5,000 meters, testifies to the incredible adaptations of deep-sea creatures.
- This discovery recalls the unexplored immensity of the oceans, of which only 5% of the depths have been mapped.
