Have you ever stopped to think about how octopuses are born? Do they have eight legs off the bat, or do they start with one? Is it more like cows (one big baby at a time) or like frogs (zillions of slimy eggs at once)?
This video will answer at least some of your questions, though probably not all of them.
Check out minute 1:02 to see the first little octopus squirt squirm out of its egg. Soon, it's a party, with baby octopuses wiggling their many legs all over the place (turns out they are born with all eight).
To make this magic happen, the mother octopus creates a den using rocks or other materials, where she will lay her vast assemblage of white, teardrop-shaped eggs—between 20,000 and 100,000 in total. She seals herself in while the munchkins form, blowing sea water to make sure they stay oxygenated and clean. This incubation period lasts anywhere between two and 10 months, depending on the species and water temperature. During this entire time, the mom gives up food in order to stand guard. But when the squishy little larval octopuses finally burst forth from their pliable swaddles, they're out there on their own.
As for how the eggs get fertilized: a male inserts a sperm packet, or spermatophore, into the female using his third right arm, which is called a hectocotylus. Copulation takes a lot out of the male, and incubation starves the female, meaning that both die not long after reproduction—and that, friends, is an exemplary example of species before self.
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