Biology
Counter-Illumination Camouflage in Midwater Cephalopods
Quick fact
Some midwater squid can match the intensity of downwelling sunlight so precisely that their silhouette disappears to predators below, even as they change their light output instantaneously to match passing clouds.
Why this is interesting
Have you ever tried to hide in the shadows of a bright room? In the ocean's twilight zone, shadows don't exist—the only light comes from above. So how do you vanish?