Why do snakes stick out their tongues?

The old belief that a snake stings with its tongue isn’t true.  The flickering tongue is actually a delicate sense organ that helps the snake to smell.  A snake’s tongue is long and forked at the end.  It darts through a small hole in the front of the snake’s mouth.  

As the snake moves along the ground, its flickering tongue senses odors in the air.  The tongue relays the information to special organs in the mouth which are linked to the snake’s sense of smell.  By picking up the odors, the tongue helps the snake to locate food and sense the presence of enemies. – Dick Rogers

How Does A Frog Catch Its Food?

Frog

The frog catches insects and other small food animals on the sticky tip of its long tongue.  All summer long, the little frog squats, motionless, on the bank of a quiet pond or brook and watches for passing insects.

If a fly or cricket passes within reach, the frog’s long tongue will snap out like a flickering whip, so fast that you can scarcely follow the action.  The insect is caught on the sticky tip.  Just as quickly the frog flips its tongue back into its mouth.

The frog’s tongue is fastened at the front of its mouth, not the back, so that it can be flipped out a long way.  The frog’s mouth is equipped with feeble, practically useless teeth, which are present only in the upper jaw.  So it must live mostly on small creatures that it can swallow in one gulp.

Frogs also eat earthworms, spiders and minnows that they catch in the water.  Toads capture their food in much of same way frogs do.  Frogs and toads help man by eating many harmful insects to be found in gardens and on farms. - Dick Rogers