Ed Yong / DIscoverMag

The argonauts are a group of octopuses unlike any other. The females secrete a thin, white, brittle shell called the paper nautilus. Nestled with their arms tucked inside this beautiful, translucent home, they drift through the open ocean while other octopus species crawl along the sea floor. The shell is often described as an egg-case, but octopus specialists Julian Finn and Mark Norman have discovered that it has another function – it’s an organic ballast tank.

An argonaut uses its shell to trap air from the surface and dives to a depth where the encased gas perfectly counteracts its own weight, allowing it to bob effortlessly without rising or sinking. Finn and Norman filmed and photographed live animals in the act of trapping their air bubbles, solving a mystery that has been debated for millennia.

Since 1923 and the work of Adolf Naef, the shell has been viewed as a container for the argonaut’s eggs. After mating with a male (who is around 8 times smaller and 600 times lighter), the female secretes the papery shell using the tips of two large tentacles. She lays her eggs within the structure before snuggling inside herself. Besides her eggs, her only housemate is one of the male’s arms – the hectocotylus. The arm doubled as a penis, snapped off during sex and stays inside the female’s body….

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  • photo by Yasushi Okumura, Japan Underwater Films

Channel Islands National Park - CA:

On June 24th, the Kelp Forest Monitoring Program staff had a very unusual sighting of an argonaut octopus (paper nautilus) in Smuggler’s Cove off Santa Cruz Island. Since argonauts typically live in tropical and subtropical waters, this is a very rare sighting and is the first live nautilus that has been observed by a park biologist.

The females produce a calcareous shell like egg case in which they reside. This “shell” contains a bubble of air that the animal captures at the surface and uses for buoyancy control. They can dive to depths of half a mile, adjusting the amount of air in their shell to keep themselves neutrally buoyant. Females can grow up to 10 cm with shells of up to 30 cm in length while males are much smaller, typically no more than 2 cm and lack a shell.

Photo credit: Michael Vecchione


Was Jules Verne just writing fanfic for science? Our current exhibition Fantastic Worlds: Science and Fiction, 1780-1910 explores the ways discoveries around science influenced popular fiction. In the case of Jules Verne, his Twenty Thousand Leagues Under the Sea that featured adventures on the sea in the submarine, the Nautilus, which takes its name from the cephalopod of the same name. Verne captured the public’s fascination with the deep unknown and lent credibility to his fiction through reading widely on the scientific advances of the day. Such sources might have included encyclopedias of the natural world like Brehm’s Tierleben, the source of the paper nautilus pictured above.

Take a slightly tangential path this Cephalopod Week, and learn about sea creatures, discoveries, ‘paper nautiluses’ and more in the chapter Sea Change in the online exhibition.


A personal series I did during my final semester at the university.  I chose to take a different approach on the idea of mermaids and I tried to stray away from the generic looking mermaids although it did start that way.  I enjoy how strange some of these pieces turned out and how they each hold their own beauty.

**Update** - I displayed these illustrations during my graduation week (December 7 - 13) in the Lowman Student Center Art Gallery and the turnout was great.  I got lots of great feedback from artists and non-artists.  The consensus was mostly positive and I was amazed and blessed to have so many people come out and support me and my work.  The prints were 24” x 36” and are now available for sale.  If anyone is interested, please message me at  Thank you to everyone who came and supported me.  It really means a lot to me.

Did you know that all Paper Nautilus shells are from Argonauta argo females?

Commonly referred to as Paper Nautilus, Argonauta argo (Octopoda - Argonautidae) is a species of cephalopod with a very particular sexual dimorphism.

The female is lodged in a boat-shaped, unchambered shell that serves primarily as brood chamber (also called egg case). This thin-walled, transversely-wrinkled shell is secreted by lobular enlargements at the tips of the dorsal arms. Female egg cases tend to be longer than female mantle lengths, so individuals can often recede completely inside the structure 

The male is dwarf, about one twentieth the size of a female; males can only reach a maximum of several centimeters in length while females can be two meters long.

Another distinctive feature of males is that they lack of shell, so all shells of the species are from females. Occasionally whole mature males are found in the shell of the female. 

References: [1] - [2]

Photo credit: ©Xavi Simona | Locality: unknown (2009)

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Genus Argonauta

(literally meaning Sailor on the Argo)

Commonly known as the paper nautilus as they bare some resemblance to a nautilus, but in fact they are a group of octopi. they are called paper nautili because the females excrete a paper thin eggcase, not a true shell. they can be found in tropical open ocean waters worldwide, closer to the surface than other ocotpi which usually live near the seabed. they can be identified by the females “shell” large eyes and unique mantle, they are extremely dimorphic as females have a shell and grow up to 10cm with a shell of 30cm, but males are alot smaller at 2cm and no shell. they got their name sailor on the argo from the historical misconception that they sail on the surface using their tentacles, this was mentioned in 20,000 leauges under the sea



Paper nautiluses, also called argonauts, secrete the shells to serve as cases for their eggs—but it has recently been discovered that they also function as air-trapping ballast tanks, which allow the cephalopods to hang effortlessly in the water column without sinking. This is the only species known to use surface air bubbles to effectively control the animals’ buoyancy.


Video of a Paper Nautilus in an aquarium located in Japan. What an amazing animal, it is beautiful.