Most of us have mercifully forgotten the plot to the 1994 Schwarzenegger/DeVito vehicle "Junior." For the purposes of scientific edification, this article will do you the disservice of reminding you that it involves the future governor of California becoming pregnant. Hilarity ensues.
Absurd concept, of course, but show this comedic gem to a seahorse, and it would shrug its shoulders (if it had them). And that's not because the film received a 32 percent rating on the Rotten Tomatoes review site, but rather because there's nothing surprising about pregnant males in the seahorse world.
When seahorses get around to reproducing, the males and females engage in an elaborate, lengthy and apparently beautiful courtship dance in which they entwine their tails and swim in tandem. Eventually, with their movements fully synchronized, the female slips a couple thousand eggs into a little pouch the male has just for that purpose.
The male fertilizes the eggs and carries them around in his pouch where they hatch. He carefully tends to their needs as they grow, and when they're ready to head off into the world he actually has muscular contractions to push them out.