Mysteries of the seas — humpback whale calls, turtle police & warming oceans

In today's episode, we dive underwater to visit creatures great and very, very small. Some of them are vocal, some are vital for the air we breathe and, sadly, many of them are threatened. How can we better protect life in the oceans? Plus — the environmental toll of your monthly bleed, and how menstrual products tell the story of the modern world, from capitalism to patriarchy to pollution.