Here is a video I found over at Deep Sea News (check it out). It shows amazing video of the seahorse, a fish. This fish is probably best known for its odd appearance almost looking like a dragon from a fairy tale. But did you know that the seahorse has a very unique reproduction strategy. The female places her eggs in the males brooding pouch where he then fertilizes the eggs and carries them for about two months until they are ready to be released. The male then cares for the young until they are ready to look after themselves. Ok so no dad is perfect and he may occasionally eat his children every now and then. But when you have a thousand of them who can blame him!!
So for all you fish geeks out there here is the reason why. Females spend twice as much energy generating the eggs than the males do incubating them. Because this is so energetically costly to the females it seems evolution has decided to give them a break, and the males incubate them instead. This means that females have more time to go and get pregnant all over again thus raising reproductive output.