The lengths male octopuses go to protect the arm they need to mate

For mating male octopuses, one limb is more important than all others. That is the third right arm or hectocotylus, which is used to transfer sperm to the female because the penis cannot do it directly. Losing the limb can severely affect their ability to father offspring, at least until a new one regenerates. That is why they take extra care to avoid damaging it or losing it to a predator, according to new research published in the journal Ethology.