If the arm has suckers all the way to the tip, you have a female. If not, the appendage is referred to as the hectocotylized arm, and the animal is male. The reason it takes a while to tell is that octopuses won’t always let you examine this arm, especially the males. They tend to keep the tip—the ligula—balled up and protected, and for good reason: This is the specialized organ for placing the spermatophore inside the female. (But he doesn’t put it between her “legs,” or arms, because that’s where her beak is. He puts it in her mantle opening—or, as Aristotle explained it, he “has a sort of
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