Paper Nautilus

No doubt every Flinders Islander will be familiar with Argonauts or Paper Nautiluses which at various times are washed up on beaches here, sometimes in very large numbers.

Argonauts, with their spectacular shells have attracted the attention of naturalists from ancient times to the present day. However there is strikingly little biological information known about them.

paper Nautilus are a type of octopus found in temperate and tropical waters world wide. There are six known species, the one found here is called Argonauts nodosa ( nodosa refers to the knobs or nodules on the shell). Only the female has a shell which serves as a brood chamber and a flotation device. This shell is secreted by the greatly extended web of one pair of arms. Young females kept in aquaria have been found to start building a shell twelve days after hatching. It is a general thought that they carry their shells throughout their lives, adding to the outer edge as they grow.

The young, which look like miniature adults when they hatch, have been collected down to a depth of 500 metres ( but mostly in the upper 100 metres.) Young males and mature females are most often caught at the surface where they feed during the the day ( on small planktonic animals caught in the web) to shallower water at night.

Unlike other cephalopods ( squids, cuttlefish and other octopus) which die soon after spawning it seems likely that paper nautilus may live for several years which might explain the variation in the size of the animals washed up.

The males are tiny, about 1.5 centimetres long. they do not have webbed arms like the females but have one very long arm which they carry in a coiled sac. This arm is called the hectocotylus and contains the sperm. During mating this arm breaks off inside the mantle or body of the female.

When first discovered, it was thought that this arm was a type of parasitic worm, and it was described in a scientific journal complete with fabricated drawings of the internal anatomy. The author later admitted his mistake.

It is not known where mating takes place as mature males are rarely caught with females.

Mass strandings as seen on Flinders Island also occur in some places on the mainland, for example Narooma and Montague Island in NSW, and Corner Inlet in Victoria. It has also been seen in other parts of the world. In Japan at times animals are caught in their thousands and sold as food in the markets.

It is uncertain whether these octopus have particular breeding grounds ( most washed up are mature females with eggs) or whether they are simply caught on currents at particular times. If breeding coincides with favourable currents the nautilus may use these to advantage.

There are a lot of gaps in our knowledge of nautilus. I would be very interested to hear any information readers have gleaned over the years regarding nautilus. In particular, I am trying to piece together what years and what time of year the shells have come in and which have been good years and bad years. This would be good to compare with other parts of Australia.

If you have any information on Paper Nautilus please contact Thelma Shaik on (03) 63592160 or E-mail Paper Nautilus

For people that wish to follow the correspondence from around the world here are a few of the e-mails, I hope they are as interesting to you as they are to me. Thanks to all the people that have emailed me details of nautilus strandings.

Emails from around the world: