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Superdads or fishy cads?

I've been told that when you hit a certain age, a biological alarm clock goes off and you go gaga, absolutely bonkers, for babies. Me? Not so much. But I'm suddenly very, very interested in seahorses.

As you may remember from your class trip to the aquarium, male seahorses and their brothers the pipefish and seadragons do something the males of no other animal species can do: They get pregnant. Here's how it works: They court (or are courted by) their aquatic ladies, who deliver a clutch of eggs for the males to fertilize. The dads carry the eggs, providing them with nutrients, until they are ready to emerge as fully-formed mini sea creatures. Meanwhile, the moms are off advancing their careers and sipping pumpkin-spice chai with their girlfriends.

Okay, maybe I'm projecting here. In any case, a new revelation published earlier this month in Nature shatters my fantasy of footloose undersea motherhood: Pipefish dads sometimes reject the eggs of "less attractive" (i.e. smaller) females after the little buns are already in the oven.

There are a couple of ways to spin this. Maybe the whole "Don't worry honey, I'll brood those eggs for you!" act is just a power grab. Carrying all those eggs around takes energy, and the dads don't want to waste effort on second-rate offspring when a really A-list mom might be right around the corner. On the other hand, maybe the most attractive pipefish ladies (or their eggs) have evolved a trick that enforces fatherly obedience chemically.

So maybe female pipefish can't really have it all. Now female fruit bats--well, that's another story

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