Winged Argonaut
Encyclopedia
Argonauta hians, also known as the winged argonaut, 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". The female of the species, like all argonaut
s, 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 tubercle
s 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. The species is preyed on by numerous predators. It has been reported in the stomach contents of Alepisaurus ferox from the south-western Pacific.
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. 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. 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 L. 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. It has been photographed atop the jellyfish Phyllorhiza punctata
in the Philippines. This behaviour has been known for a long time, although little was understood about the relationship prior to the work of Heeger et al. in 1992.
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.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of pelagic octopus
Octopus
The octopus is a cephalopod mollusc of the order Octopoda. Octopuses have two eyes and four pairs of arms, and like other cephalopods they are bilaterally symmetric. An octopus has a hard beak, with its mouth at the center point of the arms...
. The common name comes from the grey to brown coloured shell. The Chinese name for this species translates as "Grey Sea-horse's Nest". The female of the species, like all argonaut
Argonaut (animal)
The argonauts are a group of pelagic octopuses. They are also called paper nautiluses, referring to the paper-thin eggcase that females secrete...
s, 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 tubercle
Tubercle
A tubercle is generally a wart-like projection, but it has slightly different meaning depending on which family of plants or animals it is used to refer to....
s 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.
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
and South China Sea
South China Sea
The South China Sea is a marginal sea that is part of the Pacific Ocean, encompassing an area from the Singapore and Malacca Straits to the Strait of Taiwan of around...
. 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
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
, Hong Kong
Hong Kong
Hong Kong is one of two Special Administrative Regions of the People's Republic of China , the other being Macau. A city-state situated on China's south coast and enclosed by the Pearl River Delta and South China Sea, it is renowned for its expansive skyline and deep natural harbour...
and Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, 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. The species is preyed on by numerous predators. It has been reported in the stomach contents of Alepisaurus ferox from the south-western Pacific.
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. 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.
Gilbert L. Voss
Gilbert L. Voss was an American conservationist and oceanographer. He was one of the main persons behind the establishment of John Pennekamp Coral Reef State Park in Florida....
and Gordon Williamson observed six freshly mated female A. hians off Hong Kong
Hong Kong
Hong Kong is one of two Special Administrative Regions of the People's Republic of China , the other being Macau. A city-state situated on China's south coast and enclosed by the Pearl River Delta and South China Sea, it is renowned for its expansive skyline and deep natural harbour...
that were swimming along in a string.
In the open ocean, A. hians is often observed attached to jellyfish. It has been photographed atop the jellyfish Phyllorhiza punctata
Phyllorhiza punctata
Phyllorhiza punctata is a species of jellyfish, also known as the Australian spotted jellyfish or the White-spotted jellyfish. It is native to the southwestern Pacific, where it feeds primarily on zooplankton. P. punctata average 45-50 cm in bell diameter but there had been a maximum reported size...
in the Philippines. This behaviour has been known for a long time, although little was understood about the relationship prior to the work of Heeger et al. in 1992.
Underwater photographer Mark Strickland observed and photographed a female A. hians clinging to a jellyfish
Jellyfish
Jellyfish are free-swimming members of the phylum Cnidaria. Medusa is another word for jellyfish, and refers to any free-swimming jellyfish stages in the phylum Cnidaria...
in the Mergui Archipelago
Mergui Archipelago
The Mergui Archipelago is an archipelago in far southern Myanmar . It consists of more than 800 islands, varying in size from very small to hundreds of square kilometres, all lying in the Andaman Sea off the western shore of the Malay Peninsula near its landward end where it joins the rest of...
, Andaman Sea
Andaman Sea
The Andaman Sea or Burma Sea is a body of water to the southeast of the Bay of Bengal, south of Burma, west of Thailand and east of the Andaman Islands, India; it is part of the Indian Ocean....
, Myanmar
Myanmar
Burma , officially the Republic of the Union of Myanmar , is a country in Southeast Asia. Burma is bordered by China on the northeast, Laos on the east, Thailand on the southeast, Bangladesh on the west, India on the northwest, the Bay of Bengal to the southwest, and the Andaman Sea on the south....
. 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
Argonauta cornuta
Argonauta cornuta 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...
from the north east Pacific
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
and the smaller Argonauta bottgeri
Böttger's Argonaut
Argonauta bottgeri, also known as Böttger's argonaut, 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 .A. bottgeri is the...
from the Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
.
The type locality and type repository of A. hians are unknown.