Bold claim: A mysterious, never-before-seen deep-sea squid has been filmed burying itself upside down in the ocean floor, a behavior entirely undocumented in cephalopods. This stunning observation occurred in the Clarion-Clipperton Zone (CCZ), a vast abyssal plain in the Pacific that’s a focus of interest for potential deep-sea mining.
Lead author Alejandra Mejía-Saenz, a deep-sea ecologist at the Scottish Association for Marine Science, described the moment as both novel and puzzling. “The fact that this is a squid and it’s covering itself in mud—and that it is upside down—it's something we’d never seen before in any cephalopod,” she said, noting the rarity of such an observation. Co-author Bethany Fleming of the University of Southampton and the National Oceanography Centre added that witnessing burying behavior in a deep-sea squid was exciting and unexpected.
A disguised encounter on the seafloor
The event happened during the SMARTEX project, a U.K.-led expedition investigating how deep-sea mining could impact life in the CCZ. Researchers were guiding a remotely operated vehicle (ROV) over a commercial exploration area when the squid appeared beneath the ROV. Its tentacles resembled the slender stalks of nearby glass sponges or large tube worms, blending into the otherwise desolate landscape.
At first, the squid seemed unaware of the camera, but scientists quickly recognized it as a squid based on its movements and body features. Soon after, the animal vanished from the footage, prompting a moment of curiosity among the researchers. Fleming’s observation—“wait a minute, is the squid actually there?”—was followed by the realization that the creature had buried itself, leaving only two pale appendages visible. Mejía-Saenz explained that the team concluded the squid had dug into the sediment and tucked its body beneath the surface, likely as a camouflage strategy.
Why bury, and why upside down?
The team proposes two possible explanations for the tentacle-up burial posture. First, camouflage: the squid may be mimicking the appearance of surrounding structures, such as the glass sponges or tube-like organisms that dot the CCZ. By blending in, the predator risk is reduced. Second, a clever ambush for prey: with its tentacles protruding, the squid might lure crustaceans that wander near the sponges, then capture them as a byproduct of imitating inedible objects. Mejía-Saenz suggested a scenario where a crustacean is drawn to a sponge-like form, and the squid, imitating that form, would seize the opportunity to feed. This dual strategy—masquerade camouflage combined with a predatory ambush—could be an energy-efficient tactic in the food-scarce abyss.
Experts see it as masquerade with a twist
The behavior aligns with a concept biologists call masquerade: appearing as something unappealing or non-nutritious to deter predators. If the squid’s mimicry works, predators will overlook it, while its proximity to potential prey increases hunting success. Jim Barry, a senior scientist at the Monterey Bay Aquarium Research Institute (MBARI) not involved in the study, agreed that the squid’s mimicry resembles the glass sponges observed in the CCZ and noted that this kind of imitation echoes other seafloor invertebrates in the region.
Why these squids remain so elusive
Abyssal plains like the CCZ cover enormous areas yet remain among the least explored habitats on Earth. Mejía-Saenz emphasized the ocean’s vastness and the CCZ’s status as one of the least explored frontiers. Across roughly 3,100 miles (about 5,000 kilometers) of ROV tracks, the broader survey recorded only 33 cephalopod encounters, underscoring how rare and elusive these creatures can be. This scarcity helps explain why mud-covering masquerade in a deep-sea squid had not been observed before. Barry noted that limited exploration of the deep sea contributes to our partial understanding of these animals and their behaviors.
Implications for mining and conservation
The location of this sighting raises questions about the potential impacts of deep-sea mining. The CCZ is a prime candidate for extracting metals like nickel, cobalt, and manganese—materials critical for batteries and modern technology. Mejía-Saenz pointed out that mining activities would stir up sediment plumes, potentially affecting nearby life. The full extent of those consequences remains unknown, but researchers agree that understanding the biodiversity of these sites and their vulnerability to human activities is essential as we consider exploiting deep-sea resources.
What this discovery means for the deep sea
Bruce Robison of MBARI, not involved in the study, highlighted that such discoveries reveal how little we know about deep-sea squids. Deep-sea cephalopods are fast, agile, and wary, often revealing themselves only when they choose to. Each new tactic researchers uncover reminds us that there are likely many more surprises lurking in the ocean’s depths. The ongoing challenge is balancing our curiosity and resource demands with the need to safeguard these fragile, largely undocumented ecosystems.
Would you like to dive deeper into any aspect—how masquerade defenses work in other species, the specifics of the CCZ’s geology, or the ethics and science of deep-sea mining?
