Velodona: Difference between revisions
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[[File:Velodona togata1.jpg|thumb|right|A top-down view of ''V. togata'', showing the membranes connecting the arms]] |
[[File:Velodona togata1.jpg|thumb|right|A top-down view of ''V. togata'', showing the membranes connecting the arms]] |
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Chun described the first specimen he caught, a male, as looking similar to the genus ''[[Eledone]]'', but with larger [[membrane]]s, a differently shaped [[hectocotylus]], and a differently shaped [[Siphon (mollusc)|siphon]]. The specimen had "a sac-shaped body and very large eyes", with arms that "are folded back and have very large membranes which enclose the whole animal", and had a "characteristic pale coloration".<ref name=Chun></ref> Reiterating Chun, Guy Robson summarized the differences between ''Eledone'' and ''V. togata'' as "the possession of (a) a funnel organ composed of two separate pieces, (b) a sigmoid bend in the hectocotylized arm, and (c) the development of extensive lateral membranes on the arms". Robson, however, was not fully convinced that the shape of the hectocotylized arm was of value in identifying the species, positing that the curve could have been caused by a shrinkage of the membrane.<ref name=Robson>{{cite journal|last=Robson|first=Guy C.|title=26. On the Cephalopoda obtained in South African Waters by Dr. J. D. F. Gilchrist in 1920-21|journal=Proceedings of the Zoological Society of London|year=1924|month=July|volume=94|issue=2|pages=589–686|doi=10.1111/j.1096-3642.1924.tb01516.x|accessdate=17 January 2014}}</ref> |
Chun described the first specimen he caught, a male, as looking similar to the genus ''[[Eledone]]'', but with larger [[membrane]]s, a differently shaped [[hectocotylus]], and a differently shaped [[Siphon (mollusc)|siphon]]. The specimen had "a sac-shaped body and very large eyes", with arms that "are folded back and have very large membranes which enclose the whole animal", and had a "characteristic pale coloration".<ref name=Chun></ref> Reiterating Chun, Guy Robson summarized the differences between ''Eledone'' and ''V. togata'' as "the possession of (a) a funnel organ composed of two separate pieces, (b) a sigmoid bend in the hectocotylized arm, and (c) the development of extensive lateral membranes on the arms". Robson, however, was not fully convinced that the shape of the hectocotylized arm was of value in identifying the species, positing that the curve could have been caused by a shrinkage of the membrane.<ref name=Robson>{{cite journal|last=Robson|first=Guy C.|title=26. On the Cephalopoda obtained in South African Waters by Dr. J. D. F. Gilchrist in 1920-21|journal=Proceedings of the Zoological Society of London|year=1924|month=July|volume=94|issue=2|pages=589–686|doi=10.1111/j.1096-3642.1924.tb01516.x|accessdate=17 January 2014}}</ref> In comparing the distinctive features of ''V. togata'' with other known octopus species, Robson found similarities between ''V. togata'' and species in the genera ''Moschites'' (now considered a [[Synonym_(taxonomy)|synonym]] for ''[[Pareledone]]'' and ''[[Eledone]]'', both in the subfamily [[Eledoninae]]), and ''Polypus'' (now considered a synonym for ''[[Enteroctopus]]'', in the subfamily ''[[Octopodinae]]''). He found ''V. togata'' closest to the southern species of ''Moschites'', such as ''M. charcoti'' (now ''[[Pareledone charcoti]]'') and ''M. brevis'' (now ''[[Eledone massyae]]''), due to having similar funnel organs and suckers as those species.<ref name=Robson></ref> |
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The specimen's head, [[Mantle (mollusc)|mantle]], and [[Anatomical_terms_of_location#Dorsal_and_ventral|dorsal]] arms were covered in warts of varying sizes. Chun measured the specimen's mantle as being 99 millimeters wide and 80 millimeters long. The specimen's head was as wide as the mantle, and was dominated by large eyes, which were measured as 38 millimeters wide and 53 millimeters long, with sickle-shaped pupils. Chun described the arms as being "well developed", and noted that the dorsal arms were the longest, and the arms got shorter as they moved to the [[Anatomical_terms_of_location#Dorsal_and_ventral|ventral]] end. ''V. togata'' has a single line of [[Cephalopod limb|suckers]] on each arm. Chun described the membranes on the arms in detail, stating that "The arms bear dorsal and ventral membranes. The ventral margins are unusually large and extend to the tip of all arms. They are not restricted to the ventral surface but also extend to the dorsal margin of the neighboring ventral arms, where they again continue to the tip, but are more weakly developed.". The hectocotylus is on the third arm.<ref name=Chun></ref> ''V. togata'' contains an ink sac, but it is tiny and does not contain any ink, a common trait in cephalopods that live in deep water where there is little or no light.<ref name=Silva>{{cite journal|last=Silva|first=Luis|coauthors=Sobrino, Ignacio; Hernández, Eva|title=Deep-sea incirrate octopus Velodona togata (Chun, 1915) in waters off Mozambique (SW Indian Ocean): Reproductive biology, distribution, and abundance|journal=Fisheries Research|year=2013|month=August|doi=10.1016/j.fishres.2013.07.013|url=http://www.sciencedirect.com/science/article/pii/S016578361300177X|accessdate=16 January 2014}}</ref> |
The specimen's head, [[Mantle (mollusc)|mantle]], and [[Anatomical_terms_of_location#Dorsal_and_ventral|dorsal]] arms were covered in warts of varying sizes. Chun measured the specimen's mantle as being 99 millimeters wide and 80 millimeters long. The specimen's head was as wide as the mantle, and was dominated by large eyes, which were measured as 38 millimeters wide and 53 millimeters long, with sickle-shaped pupils. Chun described the arms as being "well developed", and noted that the dorsal arms were the longest, and the arms got shorter as they moved to the [[Anatomical_terms_of_location#Dorsal_and_ventral|ventral]] end. ''V. togata'' has a single line of [[Cephalopod limb|suckers]] on each arm. Chun described the membranes on the arms in detail, stating that "The arms bear dorsal and ventral membranes. The ventral margins are unusually large and extend to the tip of all arms. They are not restricted to the ventral surface but also extend to the dorsal margin of the neighboring ventral arms, where they again continue to the tip, but are more weakly developed.". The hectocotylus is on the third arm.<ref name=Chun></ref> ''V. togata'' contains an ink sac, but it is tiny and does not contain any ink, a common trait in cephalopods that live in deep water where there is little or no light.<ref name=Silva>{{cite journal|last=Silva|first=Luis|coauthors=Sobrino, Ignacio; Hernández, Eva|title=Deep-sea incirrate octopus Velodona togata (Chun, 1915) in waters off Mozambique (SW Indian Ocean): Reproductive biology, distribution, and abundance|journal=Fisheries Research|year=2013|month=August|doi=10.1016/j.fishres.2013.07.013|url=http://www.sciencedirect.com/science/article/pii/S016578361300177X|accessdate=16 January 2014}}</ref> |
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Revision as of 22:56, 17 January 2014
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| Genus: | Velodona Chun, 1915
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| Species: | V. togata
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| Velodona togata Chun, 1915
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The angel octopus (Velodona togata) is a species of octopus in the monotypic genus Velodona. Named for the distinctive membranes on its arms, the species is found in the Indian Ocean, mainly off the coast of South Africa, Mozambique, and Tanzania.
Taxonomy
Velodona togata is a species of octopus, and the sole member of the genus Velodona. It belongs to the family Octopodidae, in the order Octopoda. The species was first discovered by Carl Chun in 1915. It has two subspecies, Velodona togata togata — the subspecies originally identified by Chun in 1915 — and Velodona togata capensis, which was first described by Guy Coburn Robson in 1924.[1][2] The genus and species were named after the distinctive membranes on Velodona togata togata's arms.[3] "Velo" is Latin for veil and "toga" is Latin for gown or mantle.
Description
Chun described the first specimen he caught, a male, as looking similar to the genus Eledone, but with larger membranes, a differently shaped hectocotylus, and a differently shaped siphon. The specimen had "a sac-shaped body and very large eyes", with arms that "are folded back and have very large membranes which enclose the whole animal", and had a "characteristic pale coloration".[3] Reiterating Chun, Guy Robson summarized the differences between Eledone and V. togata as "the possession of (a) a funnel organ composed of two separate pieces, (b) a sigmoid bend in the hectocotylized arm, and (c) the development of extensive lateral membranes on the arms". Robson, however, was not fully convinced that the shape of the hectocotylized arm was of value in identifying the species, positing that the curve could have been caused by a shrinkage of the membrane.[4] In comparing the distinctive features of V. togata with other known octopus species, Robson found similarities between V. togata and species in the genera Moschites (now considered a synonym for Pareledone and Eledone, both in the subfamily Eledoninae), and Polypus (now considered a synonym for Enteroctopus, in the subfamily Octopodinae). He found V. togata closest to the southern species of Moschites, such as M. charcoti (now Pareledone charcoti) and M. brevis (now Eledone massyae), due to having similar funnel organs and suckers as those species.[4]
The specimen's head, mantle, and dorsal arms were covered in warts of varying sizes. Chun measured the specimen's mantle as being 99 millimeters wide and 80 millimeters long. The specimen's head was as wide as the mantle, and was dominated by large eyes, which were measured as 38 millimeters wide and 53 millimeters long, with sickle-shaped pupils. Chun described the arms as being "well developed", and noted that the dorsal arms were the longest, and the arms got shorter as they moved to the ventral end. V. togata has a single line of suckers on each arm. Chun described the membranes on the arms in detail, stating that "The arms bear dorsal and ventral membranes. The ventral margins are unusually large and extend to the tip of all arms. They are not restricted to the ventral surface but also extend to the dorsal margin of the neighboring ventral arms, where they again continue to the tip, but are more weakly developed.". The hectocotylus is on the third arm.[3] V. togata contains an ink sac, but it is tiny and does not contain any ink, a common trait in cephalopods that live in deep water where there is little or no light.[5]
Little is known about the reproductive habits of V. togata. A 2009 study, the first to focus on V. togata, conjectured that "The high proportion of immature females obtained in the survey (76%) and the low proportion of mature females (10%) could indicate that the spawning season is finishing at the beginning of the autumn. Moreover, the wide size range of the sampled population, with a considerable number of small individuals (possibly only a few days old)' suggests the existence of an extended reproduction period.".[5]
Habitat
The first specimen of Velodona togata (Velodona togata togata) was captured off the east coast of Africa at a depth of 749 meters below sea level.[3] According to the Integrated Taxonomic Information System (ITIS) database, Velodona togata togata is possibly located in the waters north of Zanzibar, Tanzania, while Velodona togata capensis is located off of the "Natal coast, South Africa".[1][2] In 2009, a Spanish research vessel conducted a study of the cephalopod population off the coast of Mozambique. The study found populations of V. togata across the entire study area, which ran most of the coast of Mozambique, with especially high concentrations at the very southern end of the Mozambiquan coast, in the waters near the city of Maputo. The study performed trawls in four depth groups, 200-400, 400-500, 500-600, and 600-700 meters below sea level. While V. togata was found in all four depth ranges, they were most abundant between 400 and 600 meters below sea level. The study also noted that males were most common in the shallower two groups, while females were more common in the deeper two groups.[5]
Status
The conservation status of Velodona togata has not been assessed by the IUCN Red List of Threatened Species as of IUCN Red List version 2013.2.[6]
References
- ^ a b "ITIS Standard Report Page: Velodona togata togata". Integrated Taxonomic Information System. Retrieved 16 January 2014.
- ^ a b "ITIS Standard Report Page: Velodona togata capensis". Integrated Taxonomic Information System. Retrieved 16 January 2014.
- ^ a b c d Chun, Carl (1975). Albert Mercado, trans.; Prof. O. Theodor (ed.). The Cephalopoda: Part I, Oegopsida [and] Part II, Myopsida, Octopoda. Jerusalem: Keter Publishing House. pp. 373–378. ISBN 0706512596.
{{cite book}}: CS1 maint: multiple names: editors list (link) (This is a 1975 English translation of the original, two volume work by Chun, which was published in German in 1915) - ^ a b Robson, Guy C. (1924). "26. On the Cephalopoda obtained in South African Waters by Dr. J. D. F. Gilchrist in 1920-21". Proceedings of the Zoological Society of London. 94 (2): 589–686. doi:10.1111/j.1096-3642.1924.tb01516.x.
{{cite journal}}:|access-date=requires|url=(help); Unknown parameter|month=ignored (help) - ^ a b c Silva, Luis (2013). "Deep-sea incirrate octopus Velodona togata (Chun, 1915) in waters off Mozambique (SW Indian Ocean): Reproductive biology, distribution, and abundance". Fisheries Research. doi:10.1016/j.fishres.2013.07.013. Retrieved 16 January 2014.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help); Unknown parameter|month=ignored (help) - ^ "Search Results". IUCN Red List of Threatened Species. International Union for the Conservation of Nature. Retrieved 16 January 2014.