Information about Argonauta Argo

Greater Argonaut
Eggcase of Argonauta argo
Scientific classification
Kingdom: Animalia Phylum: Mollusca Class: Cephalopoda Order: Octopoda Family: Argonautidae Genus: Argonauta Species: A. argo
Binomial name
Argonauta argo Linnaeus, 1758
Synonyms
Argonauta papyracea Roding, 1798 Argonauta grandiformis Perry, 1811 ?Argonauta striata Perry, 1811 Ocythoe antiquorum Leach, 1817 Trichocephalus acetabularis Chiaie, 1827 in 1823-1831 ?Todarus argo nom. nud. Rafinesque, 1840 Argonauta minor Risso, 1854 Argonauta naviformis Conrad, 1854 Argonauta papyria Conrad, 1854 ?Argonauta argo f. agglutinans Von Martens, 1867 ?Argonauta argo f. aurita Von Martens, 1867 ?Argonauta argo f. mutica Von Martens, 1867 ?Argonauta argo f. obtusangula Von Martens, 1867 Argonauta bulleri Kirk, 1886 ?Argonauta argo var. americana Dall, 1889 Argonauta cygnus Monterosato, 1889 Argonauta ferussaci Monterosato, 1914 Argonauta argo mediterranea Monterosato, 1914 ?Argonauta monterosatoi Coen in Monterosato, 1914 ?Argonauta monterosatoi Coen, 1914 ?Argonauta monterosatoi Coen, 1915 Argonauta sebae Valenciennes in Monterosato, 1914

The Greater Argonaut (Argonauta argo) is a species of pelagic octopus belonging to the genus Argonauta. The female of the species, like all argonauts, creates a paper-thin eggcase that coils around the octopus much like the way a nautilus lives in its shell, hence the name paper nautilus. The Chinese name for this species translates as "White Sea-horse's Nest".^[1] A. argo was the first argonaut species to be described and is consequently the type species of the genus. The female of the species, like all argonauts, creates a paper-thin eggcase that coils around the octopus much like the way a nautilus lives in its shell. A. argo is the largest species in the genus and also produces the largest eggcase. Live animals have a characteristic blue sheen on the first arm pair and around the eyes.^[1] The eggcase is characterised by two rows of small, sharp tubercles running along a narrow keel, smooth ribs across the walls of the shell, and a thickening along the shell aperture, which forms distinct protrusions or 'horns' on either side.^[1] Argonauta cygnus Monterosato, 1889 was described based on a shell which lacked these protrusions, although it is now considered a junior synonym of A. argo. The greatest recorded size of an A. argo eggcase is 300.0 mm.^[2][3]



A. argo is cosmopolitan, occurring in tropical and subtropical waters worldwide.^[1] A dwarf form exists in the Mediterranean Sea, which was described as Argonauta argo mediterranea Monterosato, 1914, although this taxon is now regarded as invalid.

A. argo is thought to feed primarily on pelagic molluscs. The species is preyed on by numerous predators. It has been reported in the stomach contents of Alepisaurus ferox from the south-western Pacific.^[4]

Males of this species reach sexual maturity at a mantle length (ML) of 8 mm.^[5] Females mature at about double the size of Argonauta bottgeri and Argonauta hians.^[5] They begin to secrete an eggcase at 6.5-7 mm ML.^[5] Eggs are usually laid when females reach 14-15 mm ML, although the size at which this takes place differs across the animal's range.^[6] A small A. argo residing in an 88 mm long eggcase was estimated to be carrying 48,800 embryos.^[7] Females grow to 100 mm ML, while males do not exceed 20 mm ML.^[1]

In the open ocean, A. argo has been observed attached to jellyfish.^[8] This behaviour has been known for a long time,^[9][8] although little was understood about the relationship prior to the work of Heeger et al. in 1992.^[10][11] In "Predation on jellyfish by the cephalopod Argonauta argo", Heeger et al. describe their observations of a female A. argo found atop a host jellyfish. The argonaut was seen holding on to the aboral (exumbrellar) surface of the jellyfish using its lateral and ventral arms. The authors found that about half of the animal's aboral surface was damaged and large pieces of mesoglea were missing, presumably removed by the argonaut. Additionally, two holes, apparently bite marks, were found in the center of this area with channels leading from these holes into the gastral cavity of the jellyfish. The argonaut presumably used these channels to suck food particles from the gastral cavity. Heeger et al. suggested that "the association provided shelter or camouflage for the argonaut".^[10][11]

Observations of captive A. argo females suggest that the expanded webs of the dorsal arms may aid the animal in feeding. Mark Norman mentions that "when food was touched against the spread webs, an arm shot out of the shell in a sweeping action, grabbing the prey".^[1] It is speculated that argonauts do not actively hunt, but employ this method to catch animals that bump into them in the open ocean.^[1]

A. argo is occasionally involved in mass strandings along the South African and southern Australian coastlines. The strandings are seasonal and generally occur between April and August, towards the end of the animals' spawning season.

A damaged beak of a female A. argo (ML = 40.0 mm; caught at ), measuring 4.30 mm in hood length and 7.80 mm in crest length, is mentioned in A Handbook for the Identification of Cephalopod Beaks.^[12]

The type specimen of A. argo was collected in the Mediterranean Sea and is deposited at the Linnean Society of London.^[13]

References

• Sweeney, M. J. (2002). Taxa Associated with the Family Argonautidae Tryon, 1879. Tree of Life web project.
• Lu, C. C. Argonautidae. Australian Biological Resources Study. Retrieved on 2006-09-13.

External links

• CephBase: Greater Argonaut
• Tree of Life web project: Argonauta

Argonauta species

A. argo • A. bottgeri • A. cornuta • A. hians • A. nodosa • A. nouryi • A. pacifica

Scientific classification or biological classification is a method by which biologists group and categorize species of organisms. Scientific classification also can be called scientific taxonomy, but should be distinguished from folk taxonomy, which lacks scientific basis.
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Mollusca
Linnaeus, 1758

Classes

Caudofoveata
Aplacophora
Polyplacophora
Monoplacophora
Bivalvia
Scaphopoda
Gastropoda
Cephalopoda
† Rostroconchia
† Helcionelloida
† ?Bellerophontida
The molluscs
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Cephalopoda
Cuvier, 1797

Orders

Subclass Nautiloidea

• †Plectronocerida
• †Ellesmerocerida
• †Actinocerida
• †Pseudorthocerida
• †Endocerida
• †Tarphycerida
• †Oncocerida

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Octopoda
Leach, 1818

Suborders

†Pohlsepia (incertae sedis)
†Proteroctopus (incertae sedis)
†Palaeoctopus (incertae sedis)
Cirrina
Incirrina
Synonyms

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Argonautidae
Tryon, 1879

Genera

Argonauta
†Izumonauta
†Kapal
†Mizuhobaris
†Obinautilus

Argonautidae
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Argonauta
Linnaeus, 1758

Species

†Argonauta absyrtus
Argonauta argo (type)
Argonauta bottgeri
Argonauta cornuta*
Argonauta hians
†Argonauta itoigawai
†
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binomial nomenclature is the formal system of naming species. The system is also called binominal nomenclature (particularly in zoological circles), binary nomenclature (particularly in botanical circles), or the binomial classification system.
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Carolus Linnaeus (Carl von Linné)

Carl von Linné, Alexander Roslin, 1775. Currently owned by and hanging at the Royal Swedish Academy of Sciences.
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In scientific nomenclature, synonyms are different scientific names used for a single taxon. Usage and terminology are different for zoology and botany.

Zoology

In zoological nomenclature, synonyms are different scientific names that pertain to the same taxon, for example
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species is one of the basic units of biological classification. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring.
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The pelagic zone is the part of the open sea or ocean that is not near the coast. In contrast, the neritic zone comprises the water that is near to (and is significantly affected by) the coast or the continental shelf.
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Octopoda
Leach, 1818

Suborders

†Pohlsepia (incertae sedis)
†Proteroctopus (incertae sedis)
†Palaeoctopus (incertae sedis)
Cirrina
Incirrina
Synonyms

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genus (plural: genera) is part of the Latinized name for an organism. It is a name which reflects the classification of the organism by grouping it with other closely similar organisms.
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Argonauta
Linnaeus, 1758

Species

†Argonauta absyrtus
Argonauta argo (type)
Argonauta bottgeri
Argonauta cornuta*
Argonauta hians
†Argonauta itoigawai
†
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A type species fixes the name of a genus (or of a taxon in a rank lower than genus).

Strictly speaking, a type species exists only in zoological nomenclature. As set in article 42.
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Argonauta
Linnaeus, 1758

Species

†Argonauta absyrtus
Argonauta argo (type)
Argonauta bottgeri
Argonauta cornuta*
Argonauta hians
†Argonauta itoigawai
†
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In scientific nomenclature, synonyms are different scientific names used for a single taxon. Usage and terminology are different for zoology and botany.

Zoology

In zoological nomenclature, synonyms are different scientific names that pertain to the same taxon, for example
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Mediterranean is a sea of the Atlantic Ocean almost completely enclosed by land: on the north by Europe, on the south by Africa, and on the east by Asia. It covers an approximate area of 2.
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For the journal, see .

A taxon (plural taxa), or taxonomic unit, is a name designating an organism or group of organisms. A taxon is assigned a rank and can be placed at a particular level in a systematic hierarchy reflecting evolutionary
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Mollusca
Linnaeus, 1758

Classes

Caudofoveata
Aplacophora
Polyplacophora
Monoplacophora
Bivalvia
Scaphopoda
Gastropoda
Cephalopoda
† Rostroconchia
† Helcionelloida
† ?Bellerophontida
The molluscs
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Alepisauridae

Genus: Alepisaurus
Lowe, 1833

Species: A. ferox
A.
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A. bottgeri

Binomial name
Argonauta bottgeri
Maltzan, 1881

Synonyms

• Argonauta boettgeri orth. var.

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A. hians

Binomial name
Argonauta hians
Lightfoot, 1786

Synonyms

• Argonauta gondola
  Dillwyn, 1817
• ?Argonauta haustrum
  Dillwyn, 1817
• ?Ocythoe cranchii

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Scyphozoa
Goette, 1887

Orders

Stauromedusae
Coronatae
Semaeostomeae
Rhizostomae
Jellyfish are marine invertebrates belonging to the Class Scyphozoa within the Phylum Cnidaria. They can be found in every ocean in the world.
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Mesoglea, also known as ectoplasma, is the clear, inert, jellylike substance that makes up most of the bodies of jellyfish, comb jellies and certain primitive sea creatures in the phylum cnidaria.
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Mark Norman is a marine biologist living in southern Australia where he works through the University of Melbourne and Museum Victoria. For over a decade, Norman has been working exclusively with cephalopods and he is one of the leading scientists in the field, having discovered and
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In biology, a type is that which fixes a name to a taxon. Depending on the nomenclature code which is applied to the organism in question, a type may be a specimen, culture, illustration, description or taxon.
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Mediterranean is a sea of the Atlantic Ocean almost completely enclosed by land: on the north by Europe, on the south by Africa, and on the east by Asia. It covers an approximate area of 2.
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The Linnean Society of London is the world's premier society for the study and dissemination of taxonomy. It publishes a Zoological Journal, as well as Botanical and Biological Journals.
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