Octopus Sex: It's Complicated
Underwater Curacao
As befits creatures of such singular forms and behavior, octopuses have evolved ingenious ways to unite sperm and egg. Since most octopuses are solitary most of the time, there are psychological barriers to be overcome if mating is to occur. It’s the males that have the most to surmount in this regard, as there is some danger lurking if the female is not receptive. By way of assessing the female’s mood, males of many species signal from a safe distance, If the female indicates that the answer is yes, the male tentatively approaches.
The octopus male extends a specialized arm, called a hectocotylus, baring packets of sperm, which is inserted under the mantle of the female. Sometimes, by way of caution, the males extends its sex arm from the maximum distance possible, lest the female’s mood changes. An extreme example is mating across adjacent dens. Not terribly intimate. But prudent, because sometimes a female octopus will eat the males, as occurs in many spiders. Even more prudent males of some species, break off the sperm arm, at the point where it enters the mantle, and make their exit. Such males obviously have no plans for further intercourse with that or any other female.
The sperm arm itself is an evolutionary masterpiece. It conveys the sperm packets from the base of the arm to the suckerless tip, then releases the packet in the appropriate location under the female’s mantle. The longer the male can keep conveying sperm packets the better for the male. In some species, though not the ones who break and run, this can take hours, as the conveyer belt is not speedy.
In many species, a female octopus can mate with several males, storing the sperm packets securely in her oviduct for weeks or months. When it comes time to lay her eggs, she releases some or all of the sperm packets at her discretion, the males having long gone. (Except in a few species, such as the blue ringed octopus, in which the males guard the postcoital females.) In essence she self inseminates her eggs.
Though non-intimate sex is the general rule for octopuses, it is not universal. Roy Caldwell (University of California, Berkeley) has documented a case of face to face sex in one eastern Pacific species, the octopus equivalent of the missionary position. (https://doi.org/10.1371/journal.pone.0134152).
The video below, of a Caribbean reef octopus, was recorded on a night dive in Curacao yesterday (Justin Rhodes videographer). It seems to be another case of octopus missionary sex. Judge for yourself.*
No telling how long they had been coupled before the video.