Researchers at the University of Nebraska-Lincoln said they found once the male dark fishing spider transfers its sperm to the female, it dies just hours later.
Once the male spider releases its sperm, it immediately seizes up, curling its legs and lying still, appearing to be dead but still technically alive, they said.
"We measured the heartbeat, and it's still there," behavioral ecologist Steven Schwartz told ABC News.
However, he said, the spider can't move and does not respond to any poking, prodding or other forms of physical stimulation, and in less than three hours the heart stops beating and the male spider is officially declared dead.
Sexually mature male dark fishing spiders often outnumber females, so there's pressure for them to mate, Schwartz said, and any advantage in passing on your own genes is a good one, even if it spells doom for the male.
"Mating is the beginning of the end," for the males, Schwartz said.