THE WOODPECKER’S TOOLS: HIS TONGUE
We have seen how the woodpecker spears his grubs: now we will study his spear.
Tongue of Hairy Woodpecker. (After Lucas.)
There are many interesting points about a woodpecker’s tongue, and they are not hard to understand. If a woodpecker would kindly let us take hold of his tongue and pull it out to its full extent we should be afraid we were “spoiling his machinery,” for the tongue can be drawn out almost incredibly—between two and three inches in a hairy woodpecker and more in a flicker. A strange-looking object it is, much resembling an angle-worm in form, color, and feeling; for it is round, soft, and sticky, except at the flat, horny, bayonet-pointed tip, and as it lies in the mouth it is wrinkled like the wrist of a loose glove; but it grows smaller and smoother the more we pull it out. Evidently we are only drawing it into its skin. But where does so much tongue come from? Does it stretch like a piece of elastic cord? Or is a part hidden somewhere? And if so, where is it kept?
Tongue-bones of Flicker. (After Lucas.)
a. Cerato-hyals, fused and short.
b. Basi-hyal, long, slender.
c. Cerato-branchials.
d. Epibranchials.
Basi-branchial is wanting.
These questions are answered by studying the bones of the tongue, for without bones it could not be guided as swiftly and surely as it is. Indeed, all tongues have bones in them, as you will discover by cutting carefully the slices near the root of an ox-tongue; but no other creature has such long and elaborate tongue-bones as some of the woodpeckers. They are the slenderest and most delicate little bony rods, joined end to end, but not really hinged nor needing to be, because they are so elastic. Here are the bones of a flicker’s tongue. The little knob at the end, marked a, bore the horny point of the tongue and directed it; the straight shaft marked b was inside the round part of the tongue as it lay within the bird’s mouth; but what was done with these two long branches, fully three quarters of the entire length of the bones? They are too sharply curved to pass down the bird’s throat, and, not being jointed, they cannot be doubled back in his mouth. They were tucked away very neatly and curiously. As the hyoid or tongue-bone lies in the mouth its branches diverge just in front of the gullet, and, traveling along the inner sides of the fork of the lower jaw, pass up over the top of the skull, looking in their sheath of muscles like two tiny whipcords. But still the bones are too long by perhaps half an inch for the place they occupy, and the ends must be neatly disposed of. Usually both pass to the right nasal opening and along the hollow of the upper mandible. Very rarely they may curl down around the eyeball in a spiral spring. So when the flicker thrusts out his tongue he feels the pull in the end of his nose, for the tip of the tongue being run out, the long slender bones are drawn out of their hiding-places, down over the skull until they lie flat along the roof of his mouth. As soon as he wishes to shut his bill, back fly the little bones guided by their hollow sheaths of elastic muscle into their hiding-place in the top of the bill. The muscular covering is a part of the same soft envelope that we saw lying in wrinkles at the root of the tongue. It covers the whole length of the little bones just as the woven outside covers an elastic cord.
