In seahorses, the male carries the embryos until birth.
During courtship, a female transfers her eggs into a specialized brood pouch on the male's abdomen. The male fertilizes the eggs inside the pouch, where the developing young receive protection and help with gas exchange and osmoregulation.
Near the end of development, the male undergoes muscular contractions and releases the young into the water. The number of offspring varies by species and the male's size, and the newborn seahorses receive little or no parental care afterward.
This reproductive arrangement is often called male pregnancy, although it differs from mammalian pregnancy because the embryos develop from eggs and the pouch is not a mammalian uterus. Seahorses are fishes in the family Syngnathidae, which also includes pipefishes and sea dragons.