The sticky tongue
They are all carnivorous, and indeed some are quite formidable such as the horned toads (Family Leptodactylidae) which can easily prey on a nestling bird or a small vertebrate such as a mouse. Although these frogs have a large mouth serviced with sharp teeth, their purpose is for defence and to grip the prey item, but does not help with breaking the prey item into smaller parts for digestion. Most amphibians are smaller and restrict their prey items to invertebrates. For this purpose an extendible tongue attached to the front of the mouth has evolved. The tongue is sticky at its tip and when it is flipped out it adheres to the small prey item which is bodily brought back into the mouth. The tongue helps with swallowing since it produces mucous which lubricates the food before passing it into the gut.