"We were blown away," said biologist Mark Norman of discovering the octopus behavior off Indonesia. "It was hard not to laugh underwater and flood your [scuba] mask."
The coconut-carrying behavior makes the veined octopus the newest member of the elite club of tool-using animals—and the first member without a backbone, researchers say.
Coconuts to Go
A team led by biologist Julian Finn of Museum Victoria in Melbourne, Australia, was observing 20 veined octopuses (Amphioctopus marginatus) on a regular basis.
The researchers noticed that the animals were frequently using their approximately 6-inch-long (15-centimeter-long) tentacles to carry coconut shells bigger than their roughly 3-inch-wide (8-centimeter-wide) bodies.
An octopus would dig up the two halves of a coconut shell, then use them as protective shielding when stopping in exposed areas or when resting in sediment.
This, on its own, astonished the team. Then they noticed that the octopuses, after using the coconut shells, would arrange them neatly below the centers of their bodies and "walk" around with the shells—awkwardly.
"I've always been impressed by what octopuses can do, but this was bizarre," said study co-author Norman, senior curator for mollusks at Museum Victoria.