How can Frogs live in Water and on Land?

Thanks for asking, Jessy!  This is a really great question, so let’s dig right into the answer.  The one thing I’m going to focus on is how frogs can breathe air on land and still get oxygen underwater.

frog has lungs.png

Breathing is how people get oxygen, O².  We pull air into our lungs, take out the oxygen, and push out carbon dioxide (die ox – ide), CO².  Fish have gills to get oxygen from water.  Water gets pushed over their gills.  The gills do the same thing that lungs do.  They take out oxygen and get rid of carbon dioxide.  Frogs are special.  At different times of their lives, frogs have both.

tadpole no lungs

When a frog is born, it comes from an egg.  It doesn’t look like a frog yet, though.  It’s called a tadpole.  Tadpoles have no legs,  but they have a tail so they can swim,.  They also have no lungs.  Tadpoles use gills to get oxygen from the water.  As a tadpole grows up, it starts to grow legs and lungs.  It will also lose its tail and its body will change so the frog can start eating bugs.  This change is called metamorphosis. (met – a – more – fa – sis)

After a tadpole becomes a frog, it has lungs.  Now it can live on the land, eat bugs, and breathe air just like people do.  But there’s also something else very special about frogs.  Frogs have a 3rd way to get oxygen.  Most frogs lose their lungs when they grow up, but they can still get oxygen when they’re underwater!  Frogs have special skin that lets oxygen in and carbon dioxide out, without using lungs or gills.  Right through the skin!  Do you know why frogs are always wet?  The skin needs to stay wet to get oxygen, so that’s why frogs are found around wet places.

yummy water oxygen

Who else has a question about frogs?


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