Why do male sea horses carry the baby?

The female sea horse deposites mature eggs in the male's pouch and the male incubates them, also protecting the young hatched fry in the pouch for a time.

The male has the babies because they are known to be more aggresive. With out this protection, pregnant female seahorses could easy be eaten or injured. Also, because few baby seahorses survive, the couple must constantly produce eggs. So, while the male has the eggs, the female is making more.