Like our friends the seahorses, pipefish leave gestation and birthing to the males, after females leave their eggs in a male's pouch. But researchers were curious -- do male gestational carriers have some of the same tricks that females use for more robust offspring? (Like a female who mates with more than one male but only uses the biggest male's sperm.)
Turns out, male pipefish can play that game too. Male pipefish were bred with one less "attractive" and one more "attractive" female (attractive meaning bigger, in pipefish parlance). Male pipefish ended up withholding resources from embryos if they were from the less attractive mate. They also provided more robustly when they were carrying eggs from the more attractive pipefish partner [source: Paczolt and Jones]. Subsequently, more embryos survived -- and were healthier -- when the male bred with the more attractive female [source: Fountain].
Now, let's not look down our nose at the pipefish. Sure, we might be less obvious about it, but the fact remains that some of us would feel a lot better about carrying the baby of the cute One Direction boy than we would about that of some Joe Schmo from off the street. He's adorable!