In seahorses, the male gives birth. This is partly because we consider the sex of an animal by the size of its gametes (sex cells)-- so the ones with the larger gametes are considered females, and the smaller are males. In seahorses, the males carry the baby and give birth. I also learned a new term-- "seahorse dads"-- to describe trans men who give birth https://youtu.be/MsHCqrrU-Gk https://theconversation.com/the-secret-sex-life-and-pregnancy-of-a-seahorse-dad-46599#:~:text=Even%20though%20fish%20don't,(sex%20cells)%20they%20produce.