Tongues have many functions – making sounds, tasting and manipulating food, and swallowing. Sharks are unusual among vertebrates in that they completely lack these handy organs.
Sharks can slosh water around in their mouths to manipulate food to some extent, but swallowing is another matter. They may compensate by using the muscles of their pectoral girdle – the equivalent of our shoulders – that supports and powers the anterior ns during swimming.
Research on white-spotted bamboo sharks has shown that a backwards shrug of the shoulders creates the suction required to draw food down into the digestive tract.
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Main image: Indonesian speckled carpetshark in Indonesia. © Borat Furlan/Getty