Nine-arm octopus
© Mainichi (file photo)The nine-armed octopus is pictured in Susami, Wakayama Prefecture in this Dec. 25, 2008
Susami, An octopus found off the coast of Susami is attracting attention for an unusual reason -- its nine arms.

The blue-ringed octopus, found by a researcher from the Susami Crustacean Aquarium, is on display.

"Octopus arms grow back if they are cut off, and it's possible that the ninth arm grew out of a wound or from some other stimulus," said aquarium head Takuya Mori.

Aquarium researcher Atsushi Hirai found the mysterious mollusk, which measures 12 centimeters in length, while looking for sea creatures late on Dec. 15 last year. Blue-ringed octopuses are small, but they possess a deadly poison, allowing them to feed on crabs and shrimp.

"When I put it in the tank and observed it, I noticed that its movements were different from those of other octopuses, and realized that it had nine arms. I was really surprised," Hirai said.

Mori said that a common octopus with 96 arms had been found in Mie Prefecture in the past, but it was the first time he had heard of a blue-ringed octopus with nine arms.