Argonaut octopus

Argonauts Temporal range: Miocene – Recent PreЄ Є O S D C P T J K Pg N
Female Argonauta argo with eggs
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Order:	Octopoda
Superfamily:	Argonautoida
Family:	Argonautidae
Genus:	Argonauta Linnaeus, 1758
Species
†Argonauta absyrtus Argonauta argo (type) Argonauta bottgeri Argonauta cornuta* Argonauta hians †Argonauta itoigawai †Argonauta joanneus Argonauta nodosa Argonauta nouryi †Argonauta oweri Argonauta pacifica* †Argonauta sismondai †Argonauta tokunagai *Species status questionable.
Synonyms
Argonautarius Dumeril, 1806 Todarus nom. nud. Rafinesque, 1815 Todarus Rafinesque, 1840 Trichocephalus Chiaje, 1827 in 1823-1831

†Argonauta absyrtus
Argonauta argo (type)
Argonauta bottgeri
Argonauta cornuta*
Argonauta hians
†Argonauta itoigawai
†Argonauta joanneus
Argonauta nodosa
Argonauta nouryi
†Argonauta oweri
Argonauta pacifica*
†Argonauta sismondai
†Argonauta tokunagai
*Species status questionable.

The argonauts (genus Argonauta, the only extant genus in the family Argonautidae) are a group of pelagic octopuses. They are also called paper nautiluses, referring to the paper-thin eggcase that females secrete. This structure lacks the gas-filled chambers present in chambered nautilus shells and is not a true cephalopod shell, but rather an evolutionary innovation unique to the genus Argonauta. It is used as a brood chamber and for trapped surface air to maintain buoyancy. It was once speculated that the argonauts did not manufacture their own eggcases but instead borrowed them from other organisms, in the manner of hermit crabs. Experiments by pioneering marine biologist Jeanne Villepreux-Power in the early 19th century disproved this hypothesis, as Villepreux-Power was able to successfully rear argonaut young and observe the development of their shells.