First Invertebrate Discovered

That Uses Tools!

Remember when we learned that the big distinction between man and the other animals was that humans used tools. Through the years we have discovered that many other vertebrates use tools including birds, chimps, dolphins, elephants, and other creatures. Now we have the first reported instance of an invertebrate that acquires tools for later use.

By Charles Q. Choi
updated 1:09 p.m. ET, Mon., Dec . 14, 2009

An octopus that uses coconut shells as portable armor is the latest addition to a growing list of animals that use tools.

The veined octopus (Amphioctopus marginatus) apparently can stack discarded coconut shell halves just as one might pile bowls, sits atop them, makes its eight arms rigid like stilts, and then moves the entire heap across the seafloor. These soft-bodied creatures perform this ungainly "stilt walking" to use the hard shells for shelter later when needed.

The discovery was a lucky accident.

"While I have observed and videoed octopuses hiding in shells many times, I never expected to find an octopus that stacks multiple coconut shells and jogs across the seafloor carrying them," said researcher Julian Finn, a marine biologist at the Museum Victoria in Australia.

In recalling the first time that he saw this behavior, Finn added, "I could tell that the octopus, busy manipulating coconut shells, was up to something, but I never expected it would pick up the stacked shells and run away. It was an extremely comical sight — I have never laughed so hard underwater."

The researchers were originally investigating the mimic octopus (Thaumoctopus mimicus) — a species that can impersonate the appearance and movements of snakes, fish and other creatures — when they chanced upon this unusual tool use on the part of the veined octopus.

Over the course of 500 hours spent diving underwater off the coasts of Northern Sulawesi and Bali in Indonesia, the researchers observed 20 veined octopuses. On four occasions, the creatures traveled up to 65 feet (20 meters) lumbering with stacked coconut shell halves beneath their bodies. Two shell-less octopuses were also seen extracting coconut shells buried under the surface and squirting jets of water at them to flush them clean of mud.