Octopus filmed walking backwards on two legs

They have eight legs and can move by jet propulsion but the octopus has another trick up its many sleeves - it can walk backwards on two legs as part of a cunning escape strategy.

Scientists have for the first time filmed bipedal walking in the octopus, which uses this unusual form of locomotion as an elaborate pretence to be an inanimate object.

One of the octopuses disguised itself as algal seaweed by dangling its other six legs around its head. The other curled its non-walking legs tightly around its body to make it look like a fallen coconut shell.

Both species carried out the mimicry while stealthily walking on their other two legs away from danger, said Crissy Huffard, a gradute student at the University of California at Berkeley who filmed the bipedal molluscs off Australia's Great Barrier Reef.

"This bipedal behaviour allows them to get away," said Ms Huffard whose pictures are published today in the journal Science.

The octopus is essentially a water-filled balloon without a skeleton. It moves around and keeps its shape with the help of muscles acting on internal hydrostatic pressure.

"This is the first underwater bipedal locomotion I know of, and the first example of hydrostatic bipedal movement," Ms Huffard said.

Octopuses normally move around by crawling on all eight legs, using their suckers to push and pull them along. The species caught walking on two legs used its limbs like the caterpillar tracks of a tank.

"It seemed like it was walking on little conveyor belts," she said.

- INDEPENDENT