Science

octopus, octopi

Jens Petersen

Ingenious Octopi Use Coconut Shells as Armor

December 15, 2009 12:30 PM
by James Sullivan
Researchers observed octopi off the Indonesian coast using coconut halves as shields and armor, making them the first invertebrates to be classified as tool-using animals.

The Coconut Defense

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A research team led by Julian Finn of Museum Victoria in Melbourne, Australia, was studying 20 veined octopi when the peculiar behavior was observed. The team was “blown away” to find that the tiny octopi carried around coconuts larger than their bodies to hide beneath, or in, when stopping in exposed areas on the sea floor.

The octopi would wrap their tentacles around the outer edges of the shells, and using suction, carry the coconuts around doing a comical tiptoe walk on the ends of their tentacles.

National Geographic reports, “Octopuses of many species are well known for their intelligence. In captivity they’ve been known to navigate mazes, seem to be able to remember past events, and are cunning escape artists.”

A press release for the study, “Tool use in an invertebrate: The coconut-carrying octopus,” is available at EurekAlert.

Background: Tool use in the animal kingdom

Octopi are by no means the only nonhuman animals that use tools, though the group is limited to an elite handful. Earlier this year crows were found to “use tools in sophisticated ways, without training, to obtain food,” Bruce Bower wrote for Science News.

Two recent studies proved the truth behind Aesop’s fable about the thirsty crow, indicating a “substantial intelligence” that allows the birds to satisfy necessity through resourcefulness.

As the Associated Press reports, a British study published in the science journal Current Biology replicated Aesop’s original fable in which “the bird comes across a pitcher with the water level too low for him to reach. The crow raises the water level by dropping stones into the pitcher.” Christopher Bird of the University of Cambridge and Nathan Emery from Queen Mary University tested this theory with rooks—relatives of the crow—and found that the birds were indeed able to reach a floating worm using rocks as tools.

According to the experiment summary, four rooks fared very well with their task, realizing “precisely how many stones were needed. Three subjects also rapidly learned to use large stones over small ones, and that sawdust cannot be manipulated in the same manner as water,” Current Biology explains. 

Although there’s no evidence of birds applying this technique in the wild, Emery and Bird suggest that the animals’ mental abilities allow them to make use of their available resources to satisfy a necessity. “Rooks do not use tools in the wild because they do not need to, not because they can’t,” Bird told Science News.

In response to the octopus discovery, LiveScience published a piece on 10 animals that use tools. Included in the article are sea otters that use stones to free abalone shells from rocks and smash them open, elephants that drop logs on electric fences to short them out and macaques that floss using hair they have pulled from the heads of tourists.
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