Manta rays glide through the ocean with their mouths open, filter feeding copious quantities of zooplankton. Parallel lobes in their mouths with tiny gaps between them let mantas eat plankton while releasing the seawater.
Water entering a manta mouth flows between the cartilaginous lobes, forming vortices before swooshing out. Instead of getting sucked into these vortices, plankton ricochet off the lobes, back toward the manta’s esophagus to be swallowed. The biological implementation is ideal. Because incoming particles are pushed away from the lobes via fluid dynamics, these filters remain clean and manta rays can continuously feed.
If there’s no clogging, they don’t have to shut their mouth and try to clean off all these little particles. ~ American marine zoologist Misty Paig-Tran