You guys like tiny sharks that glow in the dark, right?
New research has explained why the smalleye pygmy shark (pictured, with a yolk sac still attached) and lantern shark are able to make their bellies glow: camouflage. Whenever these small sharks swim close to the surface, they put themselves at risk of being spotted by larger predators below them. The glowing bellies are a form of counter-illumination, allowing their silhouette to blend in with the bright sky above.
So, how do they do it?