By Susan Milius
When a pipefish dad gets pregnant, his brood pouch delivers a surprisingly meager amount of oxygen to the embryos developing inside.
Broad-nosed pipefish (Syngnathus typhle) swimming in 100 percent oxygenated water in lab tanks delivered on average only about 50 percent of the oxygen to embryos in their brood pouches, says Inês Braga Gonçalves of the University of Zurich. Males stuck with worse water that was only 40 percent oxygenated kept the fluid in their brood pouches at only about 35 percent oxygenation.