Dad's Having the Baby
Male seahorses are the ones who get pregnant and give birth, carrying up to 2,000 babies in a specialized brood pouch.
Seahorses have completely flipped the script on reproduction: males get pregnant.
The female deposits her eggs into a special brood pouch on the male's belly. He then fertilizes them internally and carries them for 2-4 weeks, depending on the species. During this time, his pouch provides oxygen and nutrients to the developing embryos.
When it's time to give birth, the male goes through muscular contractions that can last for hours, expelling anywhere from 5 to 2,000 tiny, fully-formed seahorses. The babies are immediately independent — dad offers no parental care after birth.
Why did this role reversal evolve? Scientists believe it allows for more efficient reproduction. While the male is pregnant, the female can prepare another batch of eggs. As soon as he gives birth, she can deposit new eggs, maximizing their reproductive output.
Seahorses are also notably monogamous. Pairs perform daily greeting rituals, swimming side by side, holding tails, and sometimes changing colors together. This pair bonding likely evolved because both parents invest heavily in reproduction.