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The dark world of Octopus sex: cross-dressing, erections, cannibalism and suicide.

Updated: Jun 15, 2021

Octopus having sex
Give it to me, baby

In recent months, in Nusa Penida,Bali, Indonesia, when diving, we’ve been seeing a lot of octopus (mostly octopus cyanea or day octopus) out and about, all foolhardy and visible and very unlike their usual asocial discrete selves; and we realised it must be mating season. Elaborate skin patterns, out-in-the-open sex and all sorts of shenanigans have been witnessed. This prompted us to delve a little deeper into the dark world of octopus sex. Not for the faint of heart.

Courtship and intimidation

What we’ve been seeing recently is the courtship displays of the octopus. The males will signal that they are male by showing off black and white stripes on their whole body and especially on their ‘mating’ arm (see fuller description below). This is more intended to intimidate the other males than to seduce a female. Indeed, when the aggressive male stands tall on his tentacles and runs skin patterns from dark brown/blackish to stripy, if the other male feels intimidated, it will turn pale and move away. If the other male stands its ground, it will, in turn, stand high on its tentacles and go dark brown and flashing stripes. Females seldom refuse a male so it’s a bit of a first come first served kind of mating ritual, not very romantic really; though the males can get quite jealous (see below) understandably since the females won’t refuse whichever new suitor decides turn up.


In some species of octopus (algae octopus), the male actually guards the female from other males. The larger males select a larger female and build a den near the female’s den. They then guard the den wrestling any male who tries to come near the female. They use their ‘mating’ arm to mate from one den to the other. They occasionally have ‘affairs’ when going out foraging. However, some smaller male octopus have devised a way of mating with the female without being caught, they pretend to be female. They hide their mating arm with its the distinctive brown/back stripe pattern that identify them as male. Scientists nicknamed them ‘sneakers’. The disguise was so successful on one occasion, that one confused larger male tried to mate with his cross-dressing rival, only to discover his mistake and get pretty angry (much homoerotic wrestling ensued).

Erections and detachable penises

Surprisingly, for an animal completely devoid of any hard bits apart from its beak, the octopus does get a proper erection. The very tip (or lingula) of the octopus‘ mating arm (a.k.a the hectocotylus) can get an erection similar to that of the human penis (or for that matter clitoris). Like the human reproductive organ, the lingula’s erectile tissues get engorged with blood and harden. Scientists speculate that this may not only facilitate penetration into the female mantle cavity but may also be used as a scoop like tool to remove other males’ sperm. The opening to the mantle cavity is one of the female’s two siphons which she uses to breathe, jet out water when swimming and eject waste (I’ll refrain from making a joke in bad taste here). The male’s mating arm has a grove into which packets of sperm called spermatophores are released. Once the arm is inserted, the spermatophores are deposited into the female’s oviductal gland. When she lays her eggs weeks or months later, they will be fertilised when they pass through this area. In certain species, the male octopus does his business then just leaves his erect arm/cock behind and buggers off as quickly as possible (for reasons we’ll come back to in the next paragraph). This prompted early scientists to wrongly identify discarded hectocotylus as parasitic worms!

Sexual positions and the threat of cannibalism

Interestingly, octopus have a choice in sexual positions when mating. This is not because they have read the Kamasutra, but because the males are a bit worried about being eaten by the females. The classic guy on top position sometimes ends with the female lunging at the male, wrapping her arms around him and killing him. In one instance, a male octopus mated 12 times with a female and on his 13th go the female strangled him and carried the corpse to her den. She must have got hungry after all the exertion. In certain species, octopus have developed longer arms and mate as far away from each other as possible. The day octopus, for example, mate at arms’ length. Two octopus will sit next to each other about 15cm apart and the male will discretely insert his lingula, which being at the end of an octopus arm easily stretches that far. He’ll be ready to dart off at the first sign of his missus turning on him. Another evolutionary solution, as seen above, is just to leave the whole penis tentacle behind. Only one species are romantics and mate beak to beak, tentacle to tentacle and don’t eat their suitors.

Octopus mating
Octopus mating

Babies and suicide

If you thought the sex bit wasn’t all fun and games for the octopus, neither is the aftermath. The males get completely reckless after mating and ‘forget’ their normal survival instincts, which means they are dead/ eaten within months if not weeks after copulation. Octopus are semelparous animals, which mean they mate once in their life, then die. Fun days. After having returned to their den and laid their eggs, the females spend on average a fifth of their life span protecting and looking after their unhatched babies. They will ventilate their eggs with water to keep them clean and well oxygenated and never ever leave them even to eat. After the incubation period, which may last up to 10 months for certain species, the eggs hatch and the mother dies, just like that. A combination of hormones, starvation and guilt (only joking) end her short existence. Post-natal depression, pffff.


If octopus didn’t die soon after mating, they would probably rule the world and we’d all be a lot better off. But hey.

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