Input (grade 13): When the tongue is retracted, the prey is caught on backward-facing keratinous "teeth", located along the roof of the buccal cavity, allowing the animal both to capture and grind food.
Output (grade 8): When the tongue is retracted, the prey is caught on backward-facing keratinous "teeth", located along the roof of the buccal cavity. This allows the animal to both capture and grind food.