Meet a Bargibanti pygmy seahorse.

Bargibant’s seahorses aren’t unique for bucking gender norms—all male seahorses rear their young. But unlike many other species, H. bargibanti and its pygmy relatives (there are about a handful of species) carry the eggs in their belly rather than in a pouch at the base of their tail. “These are just adaptations, basically, because [pygmies are] so tiny,” says Smith. “If they had the brood pouch on the tail, then they would probably have difficulty with holding onto anything.”