Hectocotylus

Georges Cuvier's original illustration of an octopus hectocotylus, which he named "Hectocotyle octopodis"

A hectocotylus (plural: hectocotyli) is one of the arms of male cephalopods that is specialized to store and transfer spermatophores to the female. Structurally, hectocotyli are muscular hydrostats. Depending on the species, the male may use it merely as a conduit to the female, or he may wrench it off and present it to the female.

The name hectocotylus was devised by Georges Cuvier, who first found one embedded in the mantle of a female argonaut. Supposing it to be a parasitic worm, Cuvier gave it a generic name. The hectocotyl arm was first described in the biological works of Aristotle; although he knew of its use in mating, he was doubtful that a tentacle could deliver sperm.[1][2][3]

Anatomy

Generalized anatomy of squid and octopod hectocotyli:

Squid
Octopod

Variability

Hectocotyli are shaped in many distinctive ways, and vary considerably between species. The shape of the tip of the hectocotylus has been much used in octopus systematics.

Shape of hectocotylus Species Family
Abraliopsis morisi Enoploteuthidae
Argonauta bottgeri Argonautidae
Bathypolypus arcticus Octopodidae
Graneledone verrucosa Octopodidae
Haliphron atlanticus Alloposidae
Ocythoe tuberculata Ocythoidae
Scaeurgus patagiatus Octopodidae
Tremoctopus violaceus Tremoctopodidae
Uroteuthis duvauceli Loliginidae

References

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  1. Armand Marie Leroi. The Lagoon: How Aristotle Invented Science. https://books.google.de/books?id=-DVBAwAAQBAJ&lpg=PT79&ots=G_61_CioQn&dq=aristotle%20hectocotylus&pg=PT80#v=onepage&q=aristotle%20hectocotylus&f=false
  2. Thompson, Darcy Wentworth. 1913. On Aristotle as a biologist, with a prooemion on Herbert Spencer. Being the Herbert Spencer Lecture before the University of Oxford, on February 14, 1913. Oxford University Press. Page 19.
  3. Nixon M. & J.Z. Young J.Z. 2003. The brains and lives of Cephalopods. Oxford University Press.
  4. 4.0 4.1 Young, R.E., M. Vecchione & K.M. Mangold (1999). Cephalopoda Glossary. Tree of Life Web Project.
  5. Robson, G.C. 1929. On a case of bilateral hectocotylization in Octopus rugosus. Journal of Zoology 99(1): 95–97. doi:10.1111/j.1469-7998.1929.tb07690.x
  6. Palacio, F.J. 1973. On the double hectocotylization of octopods. PDF The Nautilus 87: 99–102.
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