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Why Do Turtles Need Shells? Why Do Frogs Hop?

Why do turtles need shells and why do they move so slowly? Why do frogs hop? Why are frogs green? Are colorful frogs poisonous? Why do frogs inflate their throats? What are some of the biggest threats to amphibians and reptiles? We wade into a Vermont pond with herpetologists Jim Andrews and Kate Kelly! We also get a preview of the new Earth Rangers podcast.


"Why do turtles need shells?" - Phillip, 7, Berkeley, CA

This episode features a fun coloring page by Vermont artist Hilary Ann Love Glass. Download and print it here. You can coloring while you listen!

Shells are a great adaptation to protect against predators. A turtle's shell is actually a part of its ribcage. Jim Andrews, a herpetologist who teaches at the University of Vermont and coordinates the Vermont Reptile and Amphibian Atlas says a good way to imagine it is to think if you could pull all your limbs inside your own ribcage!

"You pull your neck in, arms in, you pull your legs in and you're pulling them inside your ribs. [The shell] is really an extension of the turtle's ribs and so he can pull in, pull his head in, pull his arms in, pull his legs in and hide inside his ribcage. So that when fox or raccoon comes around, they can chew on the shell a little bit, but he's got great protection as a result of living inside the ribcage."

Box turtles actually have a hinge that allows them to seal their shell so nothing can bite it. Other turtles, like the painted turtle, can't fit everything totally inside of their shells. So if they're caught by a raccoon or an otter, the predator might be able to take part of a leg, or a foot, but the turtle's internal organs are still nicely protected by that shell.

That good design has helped turtles survive for a really long time! They've been around since the dinosaurs.

"But there are new threats to turtles that didn't exist before, like cars," Andrews cautions. So turtles are facing threats that their strong shells won't necessarily protect them against. Climate change is another threat that turtles are not well suited to. Andrews says habitat loss and climate change are two of the biggest threats facing all reptiles and amphibians.

Read the full transcript.

About the coloring page artist: Hilary Glass is an illustrator, printmaker and tattoo artist living in Vermont. Her content often explores flora and fauna from her local woodlands as well as imaginary creatures from other worlds entirely.  She uses pen and ink, colored pencils, watercolor and gauche as her primary illustration tools and loves to depict most things with great detail and attention to posture and body language.  You can find more info on Instagram @hilaryannloveart and at the website

A woman holds a large green frog in her hand.
Credit Melody Bodette / VPR
Green frogs are very common in the northeastern United States.


Melody is the Contributing Editor for But Why: A Podcast For Curious Kids and the co-author of two But Why books with Jane Lindholm.
Jane Lindholm is the host, executive producer and creator of But Why: A Podcast For Curious Kids. In addition to her work on our international kids show, she produces special projects for Vermont Public. Until March 2021, she was host and editor of the award-winning Vermont Public program Vermont Edition.
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