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Octopus Chronicles

Octopus Chronicles

Adventures and Discoveries with the Planet's Smartest Cephalopods

Why Is the New Deep-Sea Antarctic Octopus So Pale?

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Antarctic hydrothermal vent octopus

The deep-sea hydrothermal vent octopus discovered near Antarctica. Courtesy of Oxford University

Recent expeditions to Antarctic seafloor vents have yielded haunting new images of hairy-bellied yeti crabs, a seven-armed starfish and an eerily pale octopus—its curling arms encased in almost translucent skin.

This octopus, along with the dives' other finds, were documented via ROV (remotely operated vehicle) and described earlier this week in PLoS Biology.

"The first survey of these particular vents, in the Southern Ocean near Antarctica, has revealed a hot, dark, 'lost world' in which whole communities of previously unknown marine organisms thrive," Alex Rogers, a professor in Oxford University's zoology department who led the team, said in a prepared statement.

The octopus, found at 2,394 meters below sea level (nearly a mile and a half down), of course, isn't the first deep-sea—or the first vent-dwelling—octopus to be discovered. But it shares the same ghostly pallor as others that have been observed at similar depths. Why would these creatures, whose shallow-water cousins are so famous for their flamboyant camouflage, be slinking along as pale as a ghost?

As Janet Voight, a curator at The Field Museum in Chicago, explained to me this summer, deep-sea octopuses have little need for color or camouflage. In their dark worlds, neither predator nor prey is likely to see them. (For the same reason, these octopuses often don't bother with an ink sac—no need for a fancy visual get-away tactic in a land without light.) She has observed many of these pallid creatures over the years through her work with the ROV ALVIN, and in 2005 she even described a veritable "feeding frenzy" of a dozen pasty Pacific Ocean hydrothermal vent octopuses (Vulcanoctopus hydrothermalis) at some 2,620 meters down.

In her office, Voight has shelves and shelves of deep-sea octopuses preserved in jars—some stored singly and others smushed several to a container—collected from her expeditions. Almost all of them were about the same non-color, off-white hue. Many of her specimens had short, stubby arms and had lived primarily in the icy-cold water column near, rather than on the ground near piping-hot vents.

The team that discovered the new Antarctic sea-vent octopus was able to film the new eight-armed bottom-dweller on the go. "The back four tentacles sort of shuffle like the treads of a tank, while the front four feel in front of the octopus," Jon Copley, of the University of Southampton's National Oceanography Center and co-author on the new paper, told National Geographic. This form of locomotion isn't uncommon for octopuses that are on the prowl for dinner (possibly a tasty yeti crab or two?). And it makes plenty of sense for an octopus that lives in constant darkness would have to rely on touch—even more so than those that feel around rocks for food in sunnier environments—to catch a meal. But this shuffle was apparently too speedy for the research vehicle. "We weren't able to collect any specimens—they were quick and rare—but they're quite possibly a new species," Copley said.

Even for researchers accustomed to unfamiliar sights, the white octopus and other unusual creatures were enough to give them pause. "These findings are yet more evidence of the precious diversity to be found throughout the world's oceans," Rogers said. "Everywhere we look, whether it is in the sunlit coral reefs of tropical waters or these Antarctic vents shrouded in eternal darkness, we find unique ecosystems that we need to understand and protect."

Illustration courtesy of Ivan Phillipsen

The views expressed are those of the author and are not necessarily those of Scientific American.

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