How do underwater animals breath and live in water when it is at either a hot or cold temperature the whole time?

Question: How do underwater animals breath and live in water when it is at either a hot or cold temperature the whole time?
- Keywords:
  animal
Asked by SuperSOPHIE! :) to Maureen on 16 Nov 2018.
- Maureen answered on 16 Nov 2018:
  
  Most animals have adapted really well to life in water. Some animals, like whales, have adapted , which is a warming layer of fat. Many animals in water breathe through gills, where they take in water and take the oxygen out of it.

Question: How do underwater animals breath and live in water when it is at either a hot or cold temperature the whole time?