Among seahorses, only the male becomes pregnant. The female seahorse deposits eggs into the male’s brood pouch, where they are fertilized by the male. The young seahorses develop in the father’s pouch. The gestation period for seahorses ranges from 10 days up to 60 days, depending upon the species. The young seahorses are 1.5 centimeters (a little more than half an inch) long and are born fully formed.