HOW DO FISH BREATHE UNDER WATER?

   Fish have to breathe to stay alive, just as you do. But while you breathe oxygen from the air, fish take it from water. As they swim, fish gulp in water and push it out through slits called gills on their heads. Oxygen passes from the water into the fish's blood inside their gills.


     Fish swim by using their muscles to ripple their bodies along. Wiggling their tails from side to side gives them  extra push. They use their other fins to balance and change directions. 


     Penguins can't fly through the air because their wings are too short and stumpy. They are much more at home in the ocean, where they use their wings as flippers. Squid don't have flippers or tail, but they're still fast movers. They suck water into their bodies, then squirt it out so powerfully that their bodies shoot backwards.