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The octopus is easily identified – a soft boneless body, enormous eyes, and eight arms – not far from the way that Hollywood typically portrays aliens from outer space. But the octopus is an alien to humans for many other reasons – they are one of the ocean's most complex creatures, and one of its most enigmatic.

The octopus has lived side by side with humankind from our earliest days. But it's only now that we're beginning to unravel its secrets, and the extent of its formidable brain-power. In Aliens of the Deep Sea, scientists from around the world reveal that this already brilliant creature shares some very human traits.

In Aliens of the Deep Sea an octopus slips out of its tank and slithers surreptitiously across a concrete floor. Is it making a break for freedom? Not at all. It knows that its prey is just a short distance away in another tank. As we learn, the octopus can move on land as well as underwater – and the little round trip it has taken is not just to get from point A to point B! It's also taking this little detour because it's curious about the world it is living in.

This is not the image that we have of this invertebrate...scary monster of the deep, preying on humans, taking down ships – the stuff of myths and legend.

In La Coruña, Spain, scientists have developed a fascinating set of unusual experiments to see just how smart they are. After watching the scientists put them through their paces you'll never think about the octopus the same way again! In one novel experiment we see an octopus wrap its tentacles around a jar that has a crab inside it. In slow but determined fashion, the octopus successfully opens a screw-top jar to get to its prey. A screw-top jar is unlike anything that it would encounter in the wild – the octopus has used cognitive reasoning, not instinct, to catch its well-deserved lunch. It's hard to believe that this animal is simply a mollusk. As far as his family tree goes, the octopus is more closely related to an oyster or a snail than to any other species of animal. And yet, as we see the octopuses behave like shape shifters, moving in and out of tiny openings to get their reward, they are working out solutions in the way that humans do. They are able to think in the abstract!

In Aliens of the Deep Sea we get to see how octopuses behave in the wild too. Off the coast of Vancouver Island, underwater divers are watched by a huge octopus – a ghost like creature that lurks until it feels it's safe to emerge and be seen. It's an eerie encounter. Amazingly, with all its powerful traits, the octopus has never become king of the sea. Researchers think that it's because of the female's short life span. They give up everything, including their life, for their eggs.  But this sad reality may also be the reason that octopuses have an innate intelligence – they have no choice but to learn by trial and error. 

Just how has an animal that is so different from humans become so intelligent? From La Coruña, Spain to Vancouver Island and finally to Capri, Italy, we follow scientists in their efforts to understand how the octopus has evolved to have such intelligence, even by our standards. Through fascinating experiments in the lab, and in the wild, audiences will discover that there is still much to know about this mystifying creature.

Aliens of the Deep Sea is directed by Jérôme Julienne & John Jackson, and produced by Idéacom International and MC4.

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