Male seahorses are the ones that get pregnant.

When mating, the female seahorse will deposit unfertilized eggs into the male\'s \"brood pouch\", where the eggs will get fertilized and develop into embryos.

This interesting dynamic has unusual implications on seahorse behavioral patterns and mating rituals. Unlike with most animals, female seahorses have to compete for male partners. The females are also able to have multiple partners, while the male can only mate with one female at a time.