Hectocotylus
sex organ
A hectocotylus (pl.: 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, analogously to a penis in other animals, or he may wrench it off and present it to the female.
The hectocotyl arm was first described in Aristotle's biological works. Although Aristotle knew of its use in mating, he was doubtful that a tentacle could deliver sperm. The name hectocotylus was devised by Georges Cuvier, who first found one embedded in the mantle of a female argonaut. Thinking it to be a parasitic worm, in 1829 Cuvier gave it a generic name (Hectocotyle),
which is a New Latin term combining the Greek words for "hundred" (hec(a)to(n)) and for "hollow thing, cup" (cotyle).
Structure
Generalized anatomy of squid and octopod hectocotyli:
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.
Many coleoids lack hectocotyli altogether.
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This entry incorporates text from “Hectocotylus” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.