The Raft-Spider
There are several spiders which live on or in the water. One of these is the raft-spider, which is found in the fen districts of England. If you should happen to meet with it you can recognize it at once, for all round the upper part of its body is a narrow band of yellow, and inside this is a row of small white spots.
This spider is about an inch long, and owes its name to the fact that it actually makes a little raft on which to go out searching for water-insects. Collecting together a quantity of little bits of leaf and cut grass and reeds, it fastens them firmly together with silken threads, just as shipwrecked sailors might lash planks together with ropes in order to escape from a sinking vessel. In this way it makes a small floating platform, perhaps a couple of inches in diameter. When the raft is finished, the spider gets upon it, pushes off from the shore, and allows the current to carry it along. By and by, perhaps, it catches sight of some water-insect floating at the surface, or of a drowning fly which has fallen into the stream. Then it leaves its raft, runs along over the surface of the water, seizes its victim, and carries it back to the raft to be devoured. And if it should be alarmed, or think itself in danger, it gets under the raft and clings to the lower surface, so that it cannot be seen from above.
The Water-Spider
More curious still is the water-spider, which actually makes its nest under water. This spider, which is almost black in color, and has a very hairy body and legs, is common in ponds and canals, and spends almost the whole of its life beneath the water. Its little silken nest is shaped like a thimble, with the mouth downward, and is placed among weeds, to which it is firmly fastened down by guy-ropes, also of silk. And when it is finished the spider fills it with air. She does this in a most curious manner. Rising to the surface, she turns upside down, pokes her long hind legs out of the water, and crosses the tips. Then she dives again, carrying down a big bubble of air between these hairy legs and her equally hairy body as she does so. She next gets exactly underneath the entrance to her nest and separates her legs. The result is, of course, that the air-bubble floats up and occupies the upper part. Another bubble is now brought down in the same way, and so the spider goes on, fetching bubble after bubble, until at last her little nest is completely filled with air. Then she gets inside it, and watches for the grubs of water-insects to swim by.
In this wonderful nest the spider lays her eggs and brings up her family. When the little ones have been hatched, of course, the air in the nest very soon becomes too impure to breathe. Then the little spiders cling tightly to the walls, while the mother gets outside and tilts the whole nest sideways, so that all the exhausted air floats up in one big bubble to the surface. Then she pulls the nest back into position, hurries up to the top of the water and brings down a bubble of air, and then another, and so on until the nest is filled with air all over again.
If you ever catch one of these spiders, and keep it for awhile in a jar of water with a little piece of water-weed, you may see it spinning its wonderful nest, and filling it with air, perhaps half a dozen times a day.
Gossamers
Before we leave the spiders altogether, we must tell you something about the wonderful little creatures called gossamers. These are really the young of a good many different kinds of spiders. It often happens, of course, that several families, with perhaps five or six hundred little ones in each, are all living quite close to one another. The result is that there is not sufficient food for them all. So they make up their minds to go out into the world and seek their fortunes; and this is how they do it.
Choosing a warm, sunny morning in the early part of the autumn, all the little spiders climb the nearest bush, and each one makes its way to the very tip of a leaf. Then, clinging firmly to its hold, it begins to pour out a very slender thread of silk from one of its spinnerets. You know that on warm, sunny days the air near the ground soon becomes heated and rises, as hot air always does; and in rising it carries up these delicate gossamer-threads, as they are called, with it. Still the little spiders hold on, and pour out their lines, till at last each has several feet of thread rising straight up into the air above it. Then suddenly they all let go, and are carried up into the air at the ends of their own threads. So they go on, up and up and up, till at last they meet a gentle breeze, which carries them along with it. So, perhaps, they travel for thirty, forty, or fifty miles, or even farther still. And when at last they make up their minds to descend, all that they have to do is to roll up the threads which have been supporting them, and down they come floating gently back to earth. One good name for them is ballooning spiders.