The Argonautidae are a

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or wa ...

cephalopod A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head ...

s that inhabit tropical and temperate oceans of the world. The family encompasses the modern paper nautiluses of the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

'' Argonauta'' along with several

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genera of shelled octopods. Though argonauts are derived from benthic octopuses, they have evolved to depart the sea floor and live their life-cycle in the open seas. The family is characterised by brittle white shells constructed by the females, but which the dwarf male argonauts lack. These shells are primarily egg-cases, and are not attached to the body of the female. Paper nautiluses are often found washed up on beaches and are valued for their delicate beauty. The shell also plays the role of a buoyancy device, which the female controls by varying the amount of gulped air.Finn, Julian K., and Mark D. Norman. "The Argonaut Shell: Gas-mediated Buoyancy Control in a Pelagic Octopus." Proceedings: Biological Sciences 277, no. 1696 (2010): 2967-971. Accessed March 14, 2020. www.jstor.org/stable/27862405. All eggcases possessing nodes, ribs, and a double keel, with the exception of those of fossil ''

Kapal batavus ''Kapal'' is a monotypic genus of shelled octopods comprising the species ''Kapal batavus''. ''Kapal batavus'' was described in 1930 based on fossil material from Lower Palembang shales of Sumatra. The eggcase of this species is considerably ...

'', have been assigned to '' Argonauta''. Eggcases lacking these morphological features have been placed in the other Argonautidae genera. Fossil Argonautidae eggcases have been described from

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Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

, and

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

References

Further reading