# Evidence for direct use of terminal organ for spermatophore transfer in giant squid, Architeuthis dux

## TL;DR

This paper provides evidence that giant squids use a terminal organ for direct sperm transfer during mating, similar to a penis.

## Contribution

The study confirms the use of a terminal organ in giant squid for spermatophore transfer, resolving a long-standing question in cephalopod reproduction.

## Key findings

- Male giant squids have terminal organs that can move actively during mating.
- The terminal organ behavior in Architeuthis dux is similar to that observed in Pholidoteuthis adami.
- This finding supports the hypothesis that some deep-sea squids use a terminal organ for direct sperm transfer.

## Abstract

During mating, males of most cephalopods use a modified arm, known as a hectocotylus, to transfer spermatophores into the female. However, a long-standing enigma has been whether some deep-sea squids use a terminal organ (TO), similar to a penis, for direct spermatophore transfer, as suggested by anatomical observations. Here, we present evidence supporting this hypothesis in the giant squid,
Architeuthis dux
. Two male squids in the moribund condition were discovered in shallow water, with their TOs passing through their own funnels and being able of active movement, a behavior previously observed in
Pholidoteuthis adami
in deep water.