How the Starfish Got Its Arms (S05E20)

S05E01 What Happened to the World's Biggest Beaver? S05E02 The Reign of the Hell Ants S05E03 The Pandemic That Lasted 15 Million Years S05E04 When We First Talked S05E05 The Return of Giant Skin-Shell Sea Turtles S05E06 The Genes We Lost Along the Way S05E07 Our Bizarre, Possibly Venomous, Relative S05E08 How Worm Holes Ended Wormworld S05E09 How Humans Became (Mostly) Right-Handed S05E10 How Chilis Got Spicy (and Why We Love the Burn) S05E11 How To Survive the Little Ice Age S05E12 When Crocs Thrived in the Seas S05E13 When Trees Took Over the World S05E14 How Weasels Got Skinny S05E15 Where Are All The Squid Fossils? S05E16 Did These Giant Sloths Poop Themselves to Death? S05E17 The Traits That Spawned the Age of Mammals S05E18 The Island of the Last Surviving Mammoths S05E19 Where Are All the Medium-Sized Dinosaurs? S05E20 How the Starfish Got Its Arms S05E21 The Creature That Stumped Darwin S05E22 How Pollination Got Going Twice S05E23 How a Supervolcano Ignited an Evolutionary Debate S05E24 How a Mass Extinction Event Created the Amazon S05E25 When Mammals Only Went Out At Night S05E26 How Ancient Whales May Have Changed the Deep Ocean S05E27 How Dinosaurs Coupled Up S05E28 When It Was Too Hot for Leaves S05E29 Why The Paleo Diet Couldn't Save The Neanderthals S05E30 The Fossil Record In Your Mouth S05E31 When Pterosaurs Walked