ArgonautoidaRichard E. Young and Michael Vecchione
This tree diagram shows the relationships between several groups of organisms.
The root of the current tree connects the organisms featured in this tree to their containing group and the rest of the Tree of Life. The basal branching point in the tree represents the ancestor of the other groups in the tree. This ancestor diversified over time into several descendent subgroups, which are represented as internal nodes and terminal taxa to the right.
You can click on the root to travel down the Tree of Life all the way to the root of all Life, and you can click on the names of descendent subgroups to travel up the Tree of Life all the way to individual species.close box
All four families of the Argonautoida 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.
An incirrate octopod ...
- with detachable hectocotylus.
- 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. image info
Figure. Detached hectocotylus of Argonauta argo found wiggling among contents of a midwater trawl. Photograph (overexposed) by M. Vecchione.
- Funnel-locking apparatus well developed but structure differs among families.
- Males much smaller than females; males dwarfs in three families.
- Internal shell present only in Alloposidae; shell lost in other families.
- Radula heteroglossan.
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
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.
Richard E. Young
University of Hawaii, Honolulu, HI, USA
Page copyright © 1999 Richard E. Young and
Citing this page:
Young, Richard E. and Vecchione, Michael. 2006. Argonautoida http://tolweb.org/Argonautoida/20192/2006.07.16 in The Tree of Life Web Project, http://tolweb.org. Version 16 July 2006 (under construction).