The whale shark, like the world's second largest fish

The whale shark, like the world's second largest fish, the basking shark, is a filter feeder. In order to eat, the beast juts out its formidably sized jaws and passively filters everything in its path.  The mechanism is theorized to be a technique called “cross-flow filtration,” similar to some bony fish and baleen whales.
The whale shark is actually the world’s largest fish and have mouths up to 1.5 metres wide that contains 350 rows of teeth.
They eat by sucking vast amounts of water into their mouths where they filter feed plankton.
This photograph was taken in Isla Mujeres, Mexico, where more than 600 of the 12 metre animals converged to feed on tuna spawn.