Argonautoidea
Richard E. Young and Michael Vecchione![taxon links](/Public/treeImages/Argonautoidea.png?x=-953840498)
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close boxIntroduction
All four families of the Argonautoidea are pelagic although one (Alloposidae) is "associated" with the ocean floor. The families are primarily distinguished by an unusual means of copulation which involves transferring a detached hectocotylus from the male to the female. The clade includes gelatinous species as well as very muscular species.
Brief diagnosis:
An incirrate octopod ...
- with detachable hectocotylus.
Characteristics
- Arms
- Arm suckers in two series (grade to single series near mouth in Haliphron).
- One of third arm pair entirely hectocotylized and enrolled in a sac or pouch prior to use.
- Hectocotylized arm autotomizes (i. e., detaches) during copulation.
- Funnel
- Funnel-locking apparatus well developed but structure differs among families.
- Funnel-locking apparatus well developed but structure differs among families.
- Sexual dimorphism
- Males much smaller than females; males dwarfs in three families.
- Males much smaller than females; males dwarfs in three families.
- Shell
- Internal shell present only in Alloposidae; shell lost in other families.
- Internal shell present only in Alloposidae; shell lost in other families.
- Radula
- Radula heteroglossan.
Discussion of Phylogenetic Relationships
Naef (1923) suggested that the argonautoid families were derived from the Octopodidae and presented a phylogeny, shown above in the title frame, based on the characteristics of the hectocotylus.
Voight (1997), in a cladistic study using mostly different characters, presented a less resolved phylogeny:
\ ------ Alloposidae
\ / ----- Argonautidae
\/ /
\/------ Ocythoidae
\
\----- Tremoctopodidae
References
Naef, A. 1921/23. Cephalopoda. Fauna und Flora des Golfes von Neapel. Monograph, no. 35.
Nesis, K. N. 1982. Abridged key to the cephalopod mollusks of the world's ocean. 385+ii pp. Light and Food Industry Publishing House, Moscow. (In Russian.). Translated into English by B. S. Levitov, ed. by L. A. Burgess (1987), Cephalopods of the world. T. F. H. Publications, Neptune City, NJ, 351pp.
Voight, J. R. 1997. Cladistic analysis of the octopods based on anatomical characters. J. Moll. Stud. 63: 311-325.
About This Page
University of Hawaii, Honolulu, HI, USA
National Museum of Natural History, Washington, D. C. , USA
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Page: Tree of Life
Argonautoidea
Authored by
. Richard E. Young and Michael Vecchione.
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- Content changed 21 October 2008
Citing this page:
Young, Richard E. and Michael Vecchione. 2008. Argonautoidea http://tolweb.org/Argonautoidea/20192/2008.10.21 in The Tree of Life Web Project, http://tolweb.org/
. Version 21 October 2008.