Every night, the largest migration on Earth happens underwater, as jellies, crustaceans and fish swim up hundreds of meters towards the surface to feed. Those daily pilgrimages might also create propulsive jets behind the animals capable of stirring ocean waters, according to research in the journal Nature. Stanford engineer John Dabiri and his team investigated that phenomenon in the lab using brine shrimp (commonly known as sea monkeys). He joins Ira to discuss the theory. Plus: Consider the spleen. Many may not appreciate or even think about them very much at all, unless they’ve had them removed, but the Bajau people of Southeast Asia rely on them every day without even knowing it. The Bajau are “sea nomads,” meaning they get everything they need to live by diving up to 65 feet under water, multiple times, for up to 8 hours a day. But it’s not their large lung capacity that give them an advantage during a dive—it’s their extra large spleens. Dr. Melissa Ilardo, post-doctoral researcher in the Department of Molecular Medicine at the University of Utah, and Dr. Cynthia Beall, Professor of Anthropology at Case Western Reserve University, join Ira to discuss the spleen and other evolutionary adaptations that allow humans to survive in extreme environments. And it’s been a hard road getting there this year, but spring is finally in the air in much of the country. And that means summer is not far away, bringing with it warmer temperatures and lazy nights made for stargazing. Dean Regas, outreach astronomer at the Cincinnati Observatory and co-host of the PBS series ‘Star Gazers,’ joins Ira to talk about some of the highlights of the summer night skies, from planets to constellations to meteor showers.