30 August is the international whale sharks day. The largest fish in the sea are notable for their size and the fact that we know precious little about them. We know precious little about how and where whale sharks (Rhincodon typus) breed, their migratory patterns or any social structures. Even their lifespans remain a mystery with estimates from field data suggesting they may live for 130 years. Whale sharks have very large mouths and are filter feeders, which is a feeding mode that occurs in only two other sharks, the megamouth shark, and the basking shark. They feed almost exclusively on plankton and small fishes and pose no threat to humans.