Here's how it works:
* Water is taken in through the mouth: The fish opens its mouth and draws in water.
* Water flows over the gills: The water passes over the gills, which are feathery structures located behind the head.
* Oxygen is extracted: The gills contain tiny blood vessels called capillaries. These capillaries absorb oxygen from the water and release carbon dioxide.
* Water is expelled: The water, now depleted of oxygen and enriched with carbon dioxide, is expelled through the gills.
This process is called gills respiration, and it's how fish extract the oxygen they need to survive.