TIFFANY+-+OCTUPUSES

Back to Year 8 Newspaper =The Argonaut Octopus- The Paper Nautilus=

-"An Argonaut octopus with its shell" ~http://www.ardeaprints.com/image/paper-nautilus-argonaut-swimming-in-21-meters-down-a-drop-off_1298020.jpg

The Argonaut Octopus has long been shrouded in mystery surrounding the 'nautilus' shell that the females create. In 300 BC, Aristotle put forward a hypothesis with no evidence, that female Argonauts used their shells to sail on the surface of the sea and used its tentacles as oars and sails. Though with a total lack of proof, this theory was championed by Jules Verne who wrote about it in //'Twenty Thousand Leagues Under the Sea'//. After, since 1923 and the work of Adolf Naef, the shell was seen as a container for her eggs. Some others have suggested that the air that was trapped in the shell was used to maintain buoyancy, but that has never been proven until now.

Now this millennium long mystery has been solved. Mark Norman, the same man who discovered the Mimic Octopus, the Bottlenose Dolphin with skills similar to a chef__, and the veined Octopus that carries around c__o__co__nuts, and Julian Finn. The reason for the shell the octopus creates has been debated for centuries, but recently it has been discovered that, as well as functioning as a protective covering for her eggs, it also acts as a 'ballast tank' for the octopus. The females secrete a thin, white, brittle shell, that gained the Argonaut Octopus the name 'Paper Nautilus'.

The octopus swims to the surface of the sea, and according to what depth it would like to sink to it traps enough air in its shell to create the right amount of buoyancy. It then dives deep into the sea until the amount of air pressure in its shell is balanced with the pressure outside its shell, then it will float in the water effortlessly aided by the air in its shell, the octopus is then able to swim freely through the water.

-"The octopus sucks in air from holes at the top of its shell. It then seals it and propels itself downwards. When it reaches the right level it begins to swim." ~http://blogs.discovermagazine.com/notrocketscience/files/2010/05/Argonaut_dive.jpg

The science to it? The shell has a couple of holes at the top, which allows the Argonaut to suck in air, sealing it inside with two of its arms. When this is sealed away, it rlolls the shell downwards forcing itself down. At the depth when the compressed air cancels out its weight, becoming neutrally buoyant. Any higher than its level it will have to keep jetting to prevent itself from rising to the surface, any lower the Argonaut will sink. At the right level it can propel itself quickly through the water with no effort at all, at the right depth it can swim faster then a human diver.

-"A Chambered Nautilus" ~http://blogs.discovermagazine.com/notrocketscience/files/2010/05/Nautilus.jpg

Its much harder shelled namesake the Chambered Nautilus, have a similar way of controlling their buoyancy. Since the Chambered Nautilus has a harder shell, it is able to withstand more pressure and able to dive to deeper depths. Their shell is divided into different chambers filled with gas as their shell is permanently stuck to their bodies.

It is obvious that the Paper Nautiluses approach is far more flexible and simpler, but the Chambered Nautiluses shell can withstand increasing water pressure allowing it to dive to depths up to 750 meters.

Its penchant for deeper waters may be one of the reasons why its behavior remained unseen till now. And even though it has been seen in aquariums, the tanks simply weren't deep enough for the octopus to dive to, the Argonaut trapped air as they would in the wild but soon they simply bobbed back to the surface of the water because it was not deep enough.

Though Finn and Norman's study has uncovered a longstanding mystery it still remains an enigmatic and mysterious creature. It has been known since Ancient Greece, but its perplexing behavior makes it one of the more unknown creatures of the sea.

~Written by Tiffany Teng 8MP Resources: http://blogs.discovermagazine.com/notrocketscience/2010/05/18/the-argonaut-%E2%80%93-an-octopus-that-creates-its-own-ballast-tank/, http://www.wired.com/wiredscience/2010/05/argonaut-octopus-mystery-solved/, http://en.wikipedia.org/wiki/Argonaut_%28animal%29