Winged Argonaut

Taxobox
name = Winged Argonaut


image_caption = Eggcase of "Argonauta hians"
regnum = Animalia
phylum = Mollusca
classis = Cephalopoda
ordo = Octopoda
familia = Argonautidae
genus = "Argonauta"
species = "A. hians"
binomial = "Argonauta hians"
binomial_authority = Lightfoot, 1786
synonyms =
*"Argonauta gondola"
Dillwyn, 1817
*?"Argonauta haustrum"
Dillwyn, 1817
*?"Ocythoe cranchii"
Leach, 1817
*"Argonauta nitida"
Lamarck, 1822 "in" 1815-1822
*"Argonauta crassicosta"
Blainville, 1826
*?"Argonauta raricosta"
Leach "in" Blainville, 1826
*"Octopus" ("Philonexis") "minimus"
D'Orbigny, 1834 "in" 1834-1847
*"Argonauta owenii"
Adams & Reeve, 1848 "in" 1848-1850
*"Argonauta kochiana"
Dunker, 1852
*?"Argonauta cornuta"
Conrad, 1854
*?"Argonauta dispar"
[?="A. cornuta"]
Conrad, 1854
*"Argonauta polita"
Conrad, 1854
*?"Argonauta hians" f. "aurita"
Von Martens, 1867
*?"Argonauta hians" f. "mutica"
Von Martens, 1867
*?"Argonauta hians" f. "obtusangula"
Von Martens, 1867
*?"Argonauta expansa"
[="A. cornuta"]
Dall, 1872

The Winged Argonaut ("Argonauta hians"), also known as the Muddy Argonaut or Brown Paper Nautilus, is a species of pelagic octopus. The common name comes from the grey to brown coloured shell. The Chinese name for this species translates as "Grey Sea-horse's Nest".cite book | author = Norman, M. | year = 2000 | title = Cephalopods: A World Guide | publisher = ConchBooks | pages = pp. 189-195] 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 eggcase is characterised by a wide keel that gives it a square appearance, few rounded tubercles along the keel, and less than 40 smooth ribs across the sides of the shell. The shell is usually approximately 80 mm in length, although it can exceed 120 mm in exceptional specimens; the world record size is 121.5 mm.

"A. hians" is cosmopolitan, occurring in tropical and subtropical waters worldwide. It is an extremely variable species and there appear to exist at least two distinct forms; a "southern" form and "northern" form (see images). The former is most abundant in the Philippines and South China Sea. It is a much smaller animal, with a shell that rarely exceeds 80 mm and lacks the winged protrusions for which this species is named. The "northern" form, which is found in the waters surrounding Taiwan, Hong Kong and Japan, produces a much larger, darker and more robust shell that can reach 120 mm and has the characteristic winged protrusions. It is usually less elongated than that of the "southern" form and lacks its porcelain-like shine. Further research is needed to determine whether these forms represent two separate species or not.

"A. hians" feeds primarily on pelagic molluscs. Remains of heteropods have been reported from the stomachs of "A. hians".cite journal | author = Nesis, K. N. | year = 1977 | title = The biology of paper nautiluses, "Argonauta boettgeri" and "A. hians" (Cephalopoda, Octopoda), in the western Pacific and the seas of the East Indian Archipelago | journal = Zool. Zh. | volume = 56 | pages = 1004–1014] The species is preyed on by numerous predators. It has been reported in the stomach contents of "Alepisaurus ferox" from the south-western Pacific. [fr icon cite journal | author = Rancurel, P. | year = 1970 | title = Les contenus stomacaux d' "Alepisaurus ferox" dans le sud-ouest Pacifique (Céphalopodes) | journal = "Cah. O.R.S.T.O.M. Ser. Océanogr. | volume = 8 | issue = 4 | pages = 4–87]

Males of this species reach sexual maturity at a mantle length (ML) of about 7 mm, presumably the maximum size attained. Females mature at about half the size of "Argonauta argo". [de icon cite journal | author = Naef, A. | year = 1923 | title = Die Cephalopoden, Systematik | journal = Fauna Flora Golf. Napoli (35) | volume = 1 | pages = 1–863] They begin to secrete an eggcase at 6.5-7 mm ML. Egg laying usually commences when females reach 14-15 mm ML; by 18-20 mm ML female "A. hians" have laid their eggs. However, the size at which this takes place differs across the animal's range. Females grow to 50 mm ML, while males do not exceed 20 mm ML.

"A. hians" is known to cling to objects floating on the surface of the sea, including other argonauts.cite book | author = Voss, G. L. & G. Williamson | year = 1971 | title = Cephalopods of Hong Kong | publisher = Hong Kong: Government Press | pages = 138 pp] Chains of up to 20-30 argonauts of similar size have been reported. The first female in such chains usually clings to some inanimate object, while the other females hold onto the ventral part of the shell of the preceding animal. Gilbert Voss and Gordon Williamson observed six freshly-mated female "A. hians" off Hong Kong that were swimming along in a string.

In the open ocean, "A. hians" is often observed attached to jellyfish.cite journal | author = David, P. M. | year = 1965 | title = The surface fauna of the ocean | journal = Endeavour (Oxford) | volume = 24 | pages = 95–100 | doi = 10.1016/0160-9327(65)90007-4] It has been photographed atop the jellyfish "Phyllorhiza punctata" in the Philippines.cite web | author = Mangold, K. M., M. Vecchione & R. E. Young 1996 | title = Argonauta | url = http://www.tolweb.org/Argonauta/20204 |work = Tree of Life web project | accessdate = 2006-09-13] This behaviour has been known for a long time, [cite book | author = Kramp, P. L. | year = 1956 | chapter = Pelagic Fauna | pages = pp. 65-86 | editor = A. Bruun, SV. Greve, H. Mielche and R. Spärck, editors | title = The Galathea Deep Sea Expedition 1950-1952] although little was understood about the relationship prior to the work of Heeger "et al." in 1992. [cite journal | author = Heeger, T., U. Piatkowski & H. Möller | year = 1992 | title = Predation on jellyfish by the cephalopod "Argonauta argo" | journal = Marine Ecology Progress Series | volume = 88 | pages = 293–296 | doi = 10.3354/meps088293]

Underwater photographer Mark Strickland observed and photographed a female "A. hians" clinging to a jellyfish in the Mergui Archipelago, Andaman Sea, Myanmar. The argonaut was observed using the jellyfish as cover, rotating the animal to hide itself from potential predators (in this case the photographer). The argonaut was also seen using the jellyfish as a 'hunting platform', as it "manoeuvered its host close to a smaller comb jelly, quickly grasped it with another pair of tentacles and devoured it".

"A. hians" appears to be closely related to "Argonauta cornuta" from the north east Pacific and the smaller "Argonauta bottgeri" from the Indian Ocean.

The type locality and type repository of "A. hians" are unknown. [ [http://www.mnh.si.edu/cephs/newclass.pdf Current Classification of Recent Cephalopoda] ]

References

* Sweeney, M. J. (2002). [http://www.tolweb.org/accessory/Argonautidae_Taxa?acc_id=2464 Taxa Associated with the Family Argonautidae Tryon, 1879.] "Tree of Life web project".
*

External links

* [http://tolweb.org/tree?group=Argonauta Tree of Life web project: "Argonauta"]