Paper Nautilus Shell That Houses An Octopus Has Expanded Arms? Who is Its True Owner?

The paper nautilus shell is an unusual but beautiful shell home to the octopus that occupies it, known as Argonauta. They spend most of their lives drifting near the surface of tropical waters far from their cephalopods cousins on the seafloor. Female paper nautilus manages to do this by tucking itself into the translucent shells that they created.

Ever since the time of Aristotle, when he wrote the History of Animals, there are two things certain about the paper nautilus. The fact that they use a pair of expanded arms as sails and that the octopus occupies the shell but was made by another animal.

However, some evidence shows that neither of these "facts" is accurate.

Debunking the Two Certain Things About Paper Nautilus

Previously, people believed that paper nautilus uses their pair of expanded arms as sails and oars. The truth is, Argonauta does not cruise the oceans as people believed. But the misconception about it still slipped in the repeated story of Georges Cuvier in his Le Régne Animal in 1817 and Jules Verne's Twenty Thousand Leagues Under the Sea in 1870 when he quoted Cuvier's work.

The second misconception is a little more complex. Unlike other nautilus species, the Argonauta is not attached to the inside of its shell, which opened many questions of who was the true owner of the shell. Some believe that it was the property of another animal, wherein they could have wrestled their way in, or the real owner abandoned the shell, and the octopus only took over shortly after.

The second misconception is a lot harder to answer because the Argonauta is an ocean-going animal that mostly conducts its affairs below the waves.

ALSO READ: 'Dumbo' Octopus Living in Pacific Discovered; Researchers Say They Formed Habitat 7,000 Deep

The Woman Who Uncovered the Secrets of Argonauta

Jeanne Villepreux was born in 1794 in Juillac, France. She recorded the life of Argonauta that are inaccessible to many scientists during her time because those scientists could only examine moribund animals in glass jars or those who have been long dead that are pickled in alcohol, according to an article written by Bronwen Scott in Snails Eye View.

Jeanne recorded how the octopus nestled in its shell and how its webbed arms expanded to encase the shell. Through her experiments and observation of the species, she confirmed that the paper nautilus were neither parasites nor hijackers of the shell.

Instead, the Argonauta constructed their shell using their webbed arms. Likewise, their two arms were also used to repair any cracks of the shell by secreting layers of calcium carbonate that matched the shell's original texture and color.

Male and Female Paper Nautilus

Paper nautilus shells primarily serve as a protective case for Argonauta since females use this to deposit and care for their eggs until they hatch, Scott wrote. Meanwhile, males do not have shells, which causes another confusion about the animal.

Unlike those of other mollusks, the Argonauta shell is not primarily a retreat for the animal- it is a protective case in which the female deposits and cares for her eggs until they hatch. The males are shell-less. They are also minuscule. And this size discrepancy was another source of confusion about the animal.

Males have a specialized arm to deliver their sperms to the females. In some species of octopus, this arm can be completely detached from the male during mating and attach to females.