Organisms that breathe through gills require dissolved oxygen in the water.  How does oxygen get dissolved and how much of it do different species need?

Printables:

D.O. Visual Aid

Dissolved Oxygen Text

Additional Links:

The USGS has a good series of articles about Dissolved Oxygen.

https://www.usgs.gov/special-topic/water-science-school/science/dissolved-oxygen-and-water?qt-science_center_objects=0#qt-science_center_objects

The Chesapeake Bay Program has an interesting article about Dissolved Oxygen.

https://www.chesapeakebay.net/discover/dissolved_oxygen

A video from MIT explains dissolved oxygen.

https://www.youtube.com/watch?v=oVW5LAzd7Ec