Pregnant males!

Source: http://en.wikipedia.org/wiki/Seahorse

Seahorses reproduce in an unusual way: the male becomes pregnant. “The female inserts her ovipositor into the male’s brood pouch, where she deposits her eggs, which the male fertilizes. The fertilized eggs then embed in the pouch wall and become enveloped with tissues.”^[5] New research indicates the male releases sperm into the surrounding sea water during fertilization, and not directly into the pouch as was previously thought.^[6] Most seahorse species’ pregnancies lasts approximately two to three weeks.