Dear Kinsley,

Have you ever seen a diving beetle? They’re one of my favorite animals. They live underwater and breathe air from a bubble attached to their butts.

I talked about all the ways animals breathe underwater with my friend Wes Dowd. He’s a marine biologist and animal physiologist. He studies how living things interact with the world around them.

Animals need oxygen. For air-breathers like us, oxygen is mixed into the air. For water-breathers, oxygen is mixed into the water. To get oxygen into our bodies, we all need organs and tissues made of very thin material with lots of surface area. That means lots of places that touch the air or water where oxygen can pass through. Like inside lungs or gills. Or the skin of frogs, toads, newts and salamanders that can live on land or underwater.

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