LESSON XXX.
THE LITTLE WATER-MEN.
You know of spiders that live on land. You also know of spiders that run upon the water. There are also land-beetles and water-beetles.
The water-spiders have rafts, boats, skates, and diving-bells. They sit and float on lily leaves. Their homes are cool and bright under the clear, still waters.
There is also a happy race of beetles that have all these things. The story of these beetles is like the story of a fairy prince, but it is a true story.
A Happy Race.
A Happy Race.
All living things are fitted for the places where they are to live. The animals that live in cold lands have thick fur. Birds are made with light bodies,[18]so that they can fly easily. The fish have scaly, pointed, slippery bodies, so they can glide swiftly through the water.
So you must expect to find that the water-beetles are not quite like the land-beetles. They have bodies made fit to live in their water-home.
If you place a water-beetle beside a land-beetle, you will see that the parts of the water-beetle fitmore closely than the land-beetle’s. They join each other so as to form a smooth, water-tight case. When we build a boat, is it not our first care to make it tight, so that it will not leak?
Next you will see that the water-beetle’s body is longer, narrower, and more pointed in front than the land-beetle’s. It is made so as to part the water as it moves along. The water-beetle’s shape is more fish-like than that of the land-beetle. When we build a boat, we do not make it broad or square at both ends. We make the fore-part narrow and sharp, to cleave the water as the fish does.
As the water-beetles will swim much and walk very little, their first and second pairs of legs are small and feeble, but the hind legs are wide and strong, and reach far back. They are used for swimming.
Mr. Swimming Crab has broad hind legs, used for oars or paddles. Mr. Water-Beetle’s legs are made in much the same way, and have hairs or bristles upon them.
Though the water-beetles are to walk but little, they are to fly much, and so their wings are fine and large.
In fact, the water-beetle likes to fly. Very often he flies at night, and he seems to delight in a clear moonlight. Then the water of his pond spreadsout like a sheet of silver, and the crickets chirp in the grass. The air is moist and cool; it is sweet with the scent of flowers.
On such nights the water-beetles rise quite high into the air, and fly here and there, as if full of joy. Then they turn, close their wings, and drop into the water with a plash, like a stone.
When a number of these beetles drop with this quick plash, what do you think happens? Why, the green frogs who sit on logs or rocks, with their big eyes above the water, dive in a great fright. I wonder if the beetles think it is fun to scare the frogs? The frogs give a loud croak as they dive.
The larvæ of water-beetles live in the water, as their parents do. They are very greedy, and hunt their food as if they were angry. They have large jaws, shaped like a sickle. Their bodies are long and narrow, and they have on each side of the head six tiny eyes.
With so many eyes, they can see all about them, so they keep out of danger. They also see bugs which they wish to catch. Their straight, narrow bodies dart through the water with such quick motion as Mr. Crab has when he runs on the sand. They pounce on their prey, and their curved jaws hold it fast.
Some of these great water-beetles have a sharppoint, like a thorn, on the under side of the breast. This is not of use to kill what they eat, or to fight their enemies. The beetle seizes his prey with his jaws, or with his fore feet. But if you try to hold him, then he draws his body back, and drives this thorn into your hand.
Water-beetles have flat pads on their feet, as water-spiders do. The hairs on these pads hold tiny bubbles of air.
When these beetles wish to fly, they do not rise straight out of the water; they climb up the stem of some plant. Then, when they are high enough to make a good start, they spread their lovely wings, and skim away.
If you watch the ponds, you may see a water-beetle floating with his head down, and the tip of his tail stuck out of the water. What does he mean by that queer action?
He is getting air to breathe. Though he lives under the water, he breathes air, and he is filling up his diving-bell; or, rather, he is turning himself into a diving-bell. How does he do that? Let us see.
This beetle’s wing-covers are air-tight. The mouths of his breathing-tubes open under the wing-covers. When he has used all the fresh air he had, he wants some more. So he comes to the top of the water, turns his head down, and spreads out his feetto balance himself. Then, with a little jerk, he drives out any air that is yet under his wing-covers.
Then he draws in fresh air, shuts his wing-covers up close, and goes down with plenty of fresh, pure air to breathe.
I have known people who will shut themselves up in a room and breathe the same air over and over again.[19]The beetle, you see, is more sensible. He knows that if he is to keep his health and spirits, he must have good, fresh, clean air to breathe. So he takes all this trouble to get pure air.
FOOTNOTES:[18]See Third Book.[19]Let the teacher explain the evils of vitiated air.
[18]See Third Book.[19]Let the teacher explain the evils of vitiated air.
[18]See Third Book.
[19]Let the teacher explain the evils of vitiated air.