A chameleon squid has been discovered at a depth of 4,100 metres

The observation was made in March 2023 during visual surveys of abyssal plains in the Clarion-Clipperton Zone (CCZ) using a remotely operated vehicle (ROV). A description of the find is published in the journal Ecology.

Cephalopod molluscs - squid and octopus - are found throughout the ocean, including the deep ocean, but little is known about their behaviour and distribution in the abyssal. The reason is the difficulty of research on the ocean floor, the presumably low numbers of these animals, and their ability to avoid observational techniques.

"Hiding in plain sight."

During the ROV's passage at a depth of about 4,100 metres, the onboard camera first captured what the researchers mistook for biogenic "stems" - structures resembling glass sponges or large tubular worms. But a few seconds later, the downward-facing camera captured a squid that swam sharply into view.

Revisiting the footage, the team discovered an unexpected detail: the squid was partially buried in the mud and lying between the nodules, remaining virtually invisible. In the footage, it appeared motionless and head-down, with its siphon and two elongated tentacles extending upwards - so that they resembled the thin "stems" of benthic organisms. The squid only became visible when it stopped camouflaging and swam away - probably because of the approach of the vehicle.

The animal was described as having short arms and long white tentacles. The mantle was about 10cm long and the tentacles about 22cm long. Researchers speculate that it is a member of the family Mastigoteuthidae (the so-called "whip squids") and possibly a yet-to-be-described species.

Is it rare or just good at hiding?

The authors believe that the squid exhibited 'masquerade' behaviour - that is, they mimicked elements of the environment to hide from predators (such as beaked whales) or, conversely, to camouflage themselves to ambush prey. This way of hunting can save energy: lying in hiding is easier than actively pursuing prey.

According to the researchers, this is the first known observation of "masquerade" in deep-sea cephalopods. Earlier in the abyssal northeast Pacific whip squid met only once, and all cephalopods in the region recorded very rarely since the 1970s. The new find hints: the animals may not be so much rare as too inconspicuous - and capable of avoiding or "fooling" observation platforms.

Why it matters

The researchers remind us that abyssal areas are under increasing threats, from ocean acidification due to climate change to the prospect of deep-sea mining, especially in areas with polymetallic nodules. Abyssal plains cover more than half of the Earth's surface, and the paper emphasises how little we know about life at these depths. The authors call for more targeted studies with less 'intrusive' cameras to better assess the diversity and behaviour of deep-sea species before habitats begin to change rapidly.