What is the sticky stuff on a frog’s tongue and how does it help catch prey?

There is no special name for the sticky substance, but scientists do know it is secreted by mucous glands at the moment the frog’s tongue hits the prey. Otherwise it would stick the frog’s mouth together.

The tongue of a frog, which is hinged at the front of the mouth, not the back, can be envisioned as working like a human arm with the fist folded up to the shoulder.

When the “arm” is flipped out straight, the part of the tongue that hits the prey corresponds to the back of the hand, not the palm. Where it touches the prey, muscles in the tip contract so that it instantly exudes a sticky substance. Then, like an arm folding back up to the shoulder, it carries the prey back into the mouth.

The tongue moves in and out as fast as the blink of an eye. Then the eyes are depressed by a further set of muscles, which forces the food backward into the mouth. Once it is in the throat, hairlike projections called cilia move it toward the gut.

Some aquatic frogs have evolved with no tongues. They never come out of the water and move food into their mouths using their limbs.