Mating in pelagic octopods poses some problems. Male argonautoids have solved this simply by detaching a hectocotylized arm and giving it to the female. One submersible observation on Vitreledonella suggests that they mate a bit differently:
Figure. These pictures are from a video sequence taken from a submersible at about 900 m depth off Hawaii. A Vitreledonella drifted into view but clearly has too many arms. A closer look indicates that one octopus is within the web of another; presumably they are mating. Unfortunately, the hectocotylus cannot be identified. Photographs from Young, et al., 1999.
The females apparently brood their eggs within the mantle cavity until hatching (Joubin, 1937).
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