Because octopuses can swim, crawl and manipulate objects, they make “the ideal underwater robot,” said Francesco Giorgio-Serchi, a scientist at the Research Center on Sea Technologies and Marine Robotics here, who is working on the project.

Dr. Giorgio-Serchi and his colleagues recently acquired a 3D printer that allows them to design, experiment and revise quickly.

They aim to replicate the key features of an octopus: eight arms to provide an almost infinite range of motion; the ability to squeeze through any opening larger than its chitinous beak; and an unusual nervous system in which the arms are semiautonomous and the central brain is thought to do little more than issue general commands (“Arms, let’s go catch that crab!”).

Tentacled robots (or robotic tentacles) are still at the prototype stage. I was struck by the resemblance of this little prototype robot and the metallic spider robot described by HG Wells in his 1898 blockbuster The War of the Worlds. This little "handling machine" was remotely operated by the Martians in the same way that the Poseidrone is controlled by scientists:

As it dawned upon me first, it presented a sort of metallic spider with five jointed, agile legs, and with an extraordinary number of jointed levers, bars, and reaching and clutching tentacles about its body. Most of its arms were retracted, but with three long tentacles it was fishing out a number of rods, plates, and bars which lined the covering and apparently strengthened the walls of the cylinder... Its motion was so swift, complex, and perfect that at first I did not see it as a machine, in spite of its metallic glitter. The fighting-machines were co-ordinated and animated to an extraordinary pitch, but nothing to compare with this. People who have never seen these structures, and have only the ill-imagined efforts of artists or the imperfect descriptions of such eye-witnesses as myself to go upon, scarcely realise that living quality... ...At first, I say, the handling-machine did not impress me as a machine, but as a crablike creature with a glittering integument, the controlling Martian whose delicate tentacles actuated its movements seeming to be simply the equivalent of the crab's cerebral portion. But then I perceived the resemblance of its grey-brown, shiny, leathery integument to that of the other sprawling bodies beyond, and the true nature of this dexterous workman dawned upon me.
(Read more about metallic robot spider from The War of the Worlds)