Researchers at the Scuola Superiore Sant'Anna in Pisa, Italy have designed a biomimetic robotic octopus arm, with the goal of building a robot without rigid structure.
Octupi are renowned for their ability to reach, grasp and manipulate objects in tiny spaces with extraordinary dexterity.
Using mathematical models and prototypical mock-ups the researchers have now shown how octopus's tentacles can bend in all directions and quickly thin and elongate to almost twice their length. The researchers are currently working with colleagues in the UK, Switzerland, Turkey, Greece and Israel to test different artificial muscle technologies that will more accurately mimic tentacles.
Some further reading for you:
Research paper (Biomimetics and Bioinspiration)
Also check out the previous attempt using compressed air.