Karen Connolly, from Casey Dunn's Invertebrate Zoology (Biol 0410) course at Brown University, tells the story of how echinoderms (starfish, sea urchins, and their relatives) can change the stiffness of their skin at will.

Music by Scott Joplin (freemusicarchive.org/music/Scott_Joplin/Frog_Legs_Ragtime_Era_Favorites/09_-_scott_joplin_-_original_rags).

Visit creaturecast.org for more stories about the unexpected world of Biology.