I actually used to contribute to a science blog a few years ago. One thing I used to talk about a lot were reproductive habits of various animals. The octopus was one of my favorites. Unfortunately, the diaphragm shown in the link isn't 100% accurate.
First off, "octopuss" refers to the female gender of octopus (note the second s). As with most species, the female has all the eggs and will occasionally get drunk enough to let a male attempt to fertilize them. I say "attempt" because things aren't cut and dry when it comes to octopus fornication. So the male tries to fertilize the eggs of the female, after which she ceases any and all contact with him, be it by phone, e-mail, carrier pigeon, bike messenger, or what have you.
Moving right along, we have the male of the species, known as an "octopussy." Octo is in reference to the number of arms he has. Pussy references his mating habits. This is where it gets interesting. And pathetic.
You see, the octopussy isn't like other males in the animal kingdom. He doesn't just saunter up to a female and tell her she smells of lilacs and cumin seed before proceeding to stick his gift in her until spasming out some concentrated baby-making juice. No, he goes about it in a much different way than I do.
In order to impregnate a steaming female (yes, they steam when they're in heat, which makes them the world's only known animal capable of cooking itself), he must first give her his arm. That's not a euphemism, either, like "lay some pipe" or "plunder her parts unknown with grandpa's hickory stick." What it means is that he literally takes off one of his arms and gives it to the female. And not just any arm. He gives her the only one that matters: the hectocotylus.
You ever heard the saying "Don't put all your eggs in one basket"? Well, Mr. Oc T. Pus has not. That arm he gives her happens to be lined with his spermies. Like, all of them. Still, he just gives it right to her, no questions asked, like a pussy. Now, I wish I could report that they both live happily ever after once the female takes delivery of his arm, but that would be a bigger lie than telling Michael J. Fox he has good penmanship.
First off, the male's life is over. Again, this is not a euphemism like "Oh, man! Now that you have kids, your life is totally over!" In the octopus world, the reality is that he will literally die very soon after removing his arm.
"But at least he dies knowing that his genetics will live on through his children, right?"
Wrong. Though you'd think it would be polite to do so, the female is under no obligation to use his arm at all. She might simply decide to leave the thing - and I'm not making this part up - in her "mantle cavity". Before you ask, the answer is no, it's not a place where she keeps vintage baseball cards featuring certain Yankee centerfielders. She reneges on their hand tentacle shake deal, loverboy's line disappears faster than he can say "I'm dyin', Sookie."
And those are the in's and out's of octopus sex. I hoped you learned a little something.