The Aristotelian Anecdote on the Sailing Sea-Shell

I’ve mentioned several times before the questions that were raised in the more recent past about the supposed wisdom of the ancients and how some of their ideas were replaced by empirical scientific research. Let’s look at another example.

The Argonaut - Pierre Belon - L'histoire naturelle des estrangers poissons marins - 1551

“The nautilus is a polypus peculiar both in its nature and its actions; for it sails upon the surface of the sea, rising up from the depths of the waters. It is brought to the surface with its shell inverted, in order that it may go out more easily and navigate in an empty shell. When it reaches the surface, it turns its shell over. There is a membrane extended between two of its tentacula similar to the web feet of birds, except that theirs is thick and that of the nautilus thin and like a spider's web. This it uses for a sail when the wind blows, and it extends two of its tentacula for rudders. If alarmed, it fills its shell and sinks in the sea.”

Aristotle History of Animals Book IX Chap 25 Para 12

The Argonaut - Mrs Loudon's Entertaining Naturalist - J W Loudon - 1867

The creature Aristotle is describing in the Paper Nautilus (Argonauta argo), a cephalopod related to octopi and cuttle-fish. The English name comes from the delicate, paper-thin, white egg-case built by the females and the Latin name derives from Argus, the legendary ship-builder, who constructed the Argo, the ship that carried Jason and the Argonauts in the quest for the Golden Fleece. The beautiful shells are frequently found on Mediterranean shores (which is where the type specimen was collected). Aristotle’s description was repeated from antiquity well into the Nineteenth century – Pliny the Elder repeats it in Book IX Chap 47 of his Natural History, Oppian wrote about it in his poem Halieutics: - 

The Argonaut - J Lamarck - The Book of Shells - 1837

“Two feet they upward raise, and steady keep ;

These are the masts and rigging of the ship:

A membrane stretch'd between supplies the sail,

Bends from the masts, and swells before the gale.

Two other feet hang paddling on each side,

And serve for oars to row and helm to guide.

'Tis thus they sail, pleased with the wanton game,

The fish, the sailor, and the ship, the same.”

Lord Byron includes an allusion in The Island: -

“The tender nautilus, who steers his prow

The sea-born sailor of his shell canoe,

The ocean Mab, the fairy of the sea.

Seems far less fragile, and, alas ! more free.”

Argonauta argo - Thomas Brown - The Elements of Conchology - 1816

A particularly beautiful version is in James Montgomery’s Pelican Island: -

“Light as a flake of foam upon the wind,

Keel upward from the deep emerged a shell,

Shaped like the moon ere half her horn is fill’d;

Fraught with young life, it righted as it rose,

And moved at will along the yielding water.

The native pilot of this little bark

Put out a tier of oars on either side,

Spread to the wafting breeze a two-fold sail,

And mounted up and glided down the billow

In happy freedom, pleased to feel the air
And wander in the luxury of light.”

The Paper Nautilus sailing - Henry Lee - Sea Fables Explained - 1883

 And Alexander Pope, in his Essay on Man, wrote: -

“Learn of the little Nautilus to sail,

Spread the thin oar, and catch the driving gale.”

The class cephalopoda is divided into two subclasses – the Coleoidea (which includes octopi, squid, cuttle-fish etc and the extinct belemnites) and the Nautiloidea (the nautolids and the extinct ammonites). This is where some confusion arises – the Paper Nautilus, although a cephalopod, is not a member of the subclass nautiloidea. 

Argonauta argo - Lovell Reeve - Conchologia Systematica - Vol 2 - 1841

They get their name from the resemblance to the nautolids (from the Greek root for sailor) and the supposed sailing behaviour described by Aristotle, but the shell is actually an egg-case which forms around the female’s body and is, in effect, a nest. Although it is used as a buoyancy aid, it is not chambered like the shell of the true nautilus, which has separate air-chambers within it. 

Paper Nautilus crawling - Henry Lee - Sea Fables Explained - 1883

The female holds onto the shell with two of her eight tentacles, and often travels along the sea-bed with it raised above her. 

Swimming Nautilus - Charles Knight - A Pictorial Museum of Animated Nature - Vol 2 - 1844

When she swims, she propels herself with a siphon in the manner of other octopi, with those tentacles not holding onto the shell trailing behind her. The Paper Nautilus is usually quite a small shell, although it can reach quite large proportions – a specimen with a diameter of just over 10 inches sold in 1850s America for $500, and I have seen a shell just over 8 inches in diameter being offered for over £160 recently.

Argonauta argo