Embryos of the red-eyed tree frog have developed an interesting strategy to survive on a patchy supply of oxygen. To permeate the normally oxygen-deficient eggs, oxygen must first pass through a strong outer membrane. But even though tiny hairs called cilia stir the fluid inside these quarter-inch-diameter eggs, most of the oxygen is near the eggs’ exposed surface.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.