• Question: Why is there no oxygen in water?

    Asked by anon-193413 to iainstaniland on 12 Nov 2018.
    • Photo: Iain Staniland

      Iain Staniland answered on 12 Nov 2018:

      The simple answer is there is oxygen in water. A water molecule is made up three atoms.
      2 hydrogen atoms (H) bonded to one oxygen atom (O)
      hence it is often referred to as H2O.

      But it is difficult to split this into the separate atoms so fish actually breathe something called dissolved oxygen. Which is oxygen in the form of a gas (like in the air) that is mixed in with the water molecules.
      see: https://water.usgs.gov/edu/dissolvedoxygen.html

      Fish and other animals that live in the water can use this to breathe via their gills or other specialist organs. However Marine Mammals and Birds have to breathe air as they have lungs. So they must come to the surface to get their oxygen.

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