Eleven years ago, a mysterious disease killed most of the adult starfish off California and Oregon. The most severely affected, Sunflower Seastar, was the main predator limiting the spread of Purple Urchins. The sudden disappearance of a key predator triggered a "trophic cascade" that led to an ongoing ecological crisis, including the collapse of the kelp forests. After a decade of painstaking research, the pathogen responsible for Seastar Wasting Disease has finally been identified.

Gray Whales were once nearly wiped out by commercial whaling. Once that ceased in the late 20th century, they staged a remarkable comeback, reaching a population of around 26,000 by 2016. But since then many have died on migration, and a new estimate indicates their population has been cut in half. We talk with Dr. Aimee Lang of the NOAA Southwest Fisheries Science Center about that estimate, and what might be causing the decline of these iconic marine mammals.

Just when you think you've got life all figured out... scientists find something that redefines the whole concept. Ecology Hour hosts Bob Spies and Tim Bray talk with Dr. Karen Lloyd, Professor of Earth Sciences at the University of Southern California, about her research into alien life forms right here on Earth - what she calls "Intraterrestrials" in her new book. Some of these organisms challenge our basic understanding of life: their metabolic processes function so slowly that individuals may live for hundreds of thousands of years. Some of them can breathe Arsenic; others eat methane and produce formaldehyde. Their discovery has created a new and wild frontier in scientific research, and Dr. Lloyd is in the vanguard.