Question: Why do male seahorses get pregnant and not the female seahorses?

Daren Fearon answered on 22 Jun 2014:

While male seahorses carry seahorse eggs they don’t produce them. The female sea horse produces the eggs and then deposits them in the male who then fertilises them and carries them. Scientists aren’t sure why sea horses evolved to do this but it in some way improves survival of their species. Sea horses aren’t very efficient at reproducing, only about 5 of every 1000 eggs survive. By depositing the eggs in the male the female can get to work on producing more eggs, improving the numbers likely to make it to adulthood. This method also shares the work load more. The female uses her energy and nutrients to produce the eggs and may not be prepared to protect the eggs. The male will have more energy to look after the eggs.