Intermediate 
An octopus has escaped from the National Aquarium in New Zealand by leaving its tank, sliding down a 50-metre drainpipe and disappearing into the sea. Inky  a common New Zealand octopus  escaped after the lid of his tank was accidentally left a bit ajar. Staff believe that in the middle of the night, while the aquarium was deserted, Inky climbed to the top of his glass enclosure, down the side of the tank and travelled across the floor of the aquarium.
Rob Yarrell, national manager of the National Aquarium of New Zealand in Napier, said: Octopuses are famous for their ability to escape. I dont think he was unhappy with us, or lonely, because octopuses are solitary creatures. But, he is such a curious boy. He wanted to know what was happening on the outside. Thats just his personality.
One theory is that Inky slid across the aquarium floor  a journey of three or four metres  and, then, into a drainpipe that led directly to the sea. The drainpipe was 50 metres long and led to the waters of Hawkes Bay, on the east coast of New Zealands North Island.
It is also possible that Inky escaped by squeezing into an open pipe at the top of his tank, which led under the floor to the drain. When we came in the next morning and his tank was empty, I was really surprised, said Yarrell, who has not launched a search for Inky. The staff and I have been pretty sad. But then, this is Inky and hes always been a bit of a surprise octopus.
Reiss Jenkinson, exhibits keeper at the National Aquarium, said he was absolutely certain Inky was not stolen. I understand octopus behaviour very well, he said. I have seen octopuses on boats escape through bilge pumps. And, the security here is too tight for anyone to take Inky and why would they?
Because octopuses have no bones, they are able to fit into extremely small spaces and can squeeze through gaps the size of coins. They are also extremely intelligent and can use tools. At the Island Bay Marine Education Centre in Wellington, an octopus used to visit another tank during the night to steal crabs, then return to its own tank. Another at the centre, Ozymandias, broke a world record for opening a jar.
Inky was brought to the National Aquarium several years ago by a local fisherman who found him caught in a fishing pot. He was rough looking, with very short arms, said Yarrell. He had been living on the reef and fighting with fish so he wasnt in the best shape. According to Yarrell, Inky  who is about the size of a rugby ball  was an unusually intelligent octopus. He was very friendly and a popular attraction here. We have another octopus, Blotchy, but he is smaller than Inky and Inky had the personality.
The aquarium has no plans to step up security as a result of the escape because they dont think it will happen again. But, the staff are more and more aware of what octopuses can do. Although the aquarium is not looking for a replacement for Inky, if a fisherman brought in another octopus, it might accept it. You never know, said Yarrell. Theres always a chance Inky could come home to us.