The creature was seen for the first time in footage taken in 2005 by Woods Hole Oceanographic Institution ecologist Tim Shank. In the video and the accompanying research paper, published this week in the journal Current Biology, Shank and his colleagues report that within 10 minutes of hatching, the young octopus behaved like a fully grown adult. It could swim, survey its environment and detect chemical signals. Well-developed suckers on its arms suggest it would even be capable of catching prey.
“We therefore conclude that [dumbo octopuses] hatch as competent juveniles,” the study authors write.
Shank discovered the infant octopus while on a cruise of the seamounts — underwater peaks — in the North Atlantic. With a remote-operated underwater vehicle, or ROV, he spotted what looked like bumpy balls of chocolate clinging to the branches of a cold-water coral almost 8,000 feet below the surface. He directed the ROV to scoop up the spheres and bring them back to the surface.
It turned out the strange chocolate-colored specimens were egg cases. The first two were broken open and empty, and the next two were filled with a glob of white jelly. But the fifth — whole and apparently full — began to crack open as he retrieved it from the ROV's sampling box. By the time Shank made it to the ship's lab, a tiny octopus had emerged.
“Once the fins were observed while it was still in the bucket, it was clear that it was a dumbo octopod,” co-author Elizabeth Shea said in a news release. Shea is curator of mollusks at the Delaware Museum of Natural History.
Waving its huge ear flaps — each about as large as the rest of its tiny body — it swam around a small dish, bumping its mantle against the clear glass sides. The hatchling bore a sac filled with rich yolk, which likely would help keep the young octopus nourished as it figured out how to feed.
Not much is known about the genus Grimpoteuthis, which includes the 14 known species of dumbo octopuses. They dwell almost exclusively in the ocean's darkest depths, out of reach for all but the hardiest submersibles. Very few specimens have been collected, and little of their DNA has been sequenced. For this reason, Shank, Shea and their colleagues couldn't determine the hatchling's species.
The researchers are intrigued by the apparent link between the eggs and the corals on which they are laid, which may be threatened by trawlers and deep-sea mining. Understanding the environments that rare animals such as dumbo octopuses depend on for survival can help scientists come up with strategies to protect them.
Correction: An earlier version of this post inaccurately stated characterized the current danger that mining efforts pose to deep-water corals.