Fig. 175.—Jaws of a spider.
The male and female spiders often present a very different appearance, the male being smaller. The spiders deposit eggs which are inclosed in silken balls or nests of various kinds, in which they remain until the young are hatched. Some are concealed in the web; others are placed underground; and some are perched upon a stalk resembling a plant.
There appears to be no limit to the uses to which the marvelous silk of spiders is put. Some spiders form balloons with which they sail away through the air. I have seen scores of these aëronauts in the air at one time. Another form constructs a raft of leaves bound together with silk. Some build nets for small game, as gnats. The silken cord made by others is so tough that it can be used as thread.
By partly destroying a web and suspending a black cloth behind the locality, the operations of the spider in building and repairing can be plainly seen. It is well to place the spinnerets beneath a microscope, under which they appear to be made up of many points. Touch one of these and a glutinous secretion adheres, which when stretched is seen to be silk, and each point provides a separate thread which joins with the others, producing one cable. The spinnerets are to some extent movable. They can be turned to the right or left, and wherever they touch, the silk remains glued fast. This explains why the spider moves and works so quickly and accomplishes so much. The amount of silk secreted is astonishing, and some idea of it can be obtained by walking over the country in spring, early in the morning. On the slopes of the Sierra Madre, in the San Gabriel Valley, I have seen the surface of the ground for a great distance covered with webs which caught the rays of the sun as it rose, presenting a most beautiful appearance. This fabric covered hundreds of acres in a fairy maze of web, so many traps for unwary small fry of the insect world. With a small stick I have wound a large amount of silk from the spinnerets of a spider, there apparently being no diminution of the supply. Professor Burt Wilder wound from the large spider known as Nephila plumipes several miles of silk. Some spiders have long, slender legs and are rapid runners. Others, as Salticus, are very deliberate, but powerful leapers, jumping upon their prey like a cat. Perhaps the most remarkable leaping spider is one from Australia, called the flying Attus, having singular flaps or winglike extensions upon its sides. One of the spiders not only runs over the surface of the water readily, but spends a part of its time under the surface, carrying down a bubble of air for its supply of oxygen, the bubble acting as a diving bell.
The spiders are very solicitous of their young, placing every safeguard about them, and resenting any attack by a fierce rush. Several large spiders (Fig. 176) carry their young upon their backs. The little spiders are rubbed or scraped off when they become too great a burden. The spiders are natural hunters and trappers, and a volume could be written on their methods and adventures in running down prey. Once as I was crawling through the almost stifling brush of one of the Florida Keys I came to a little opening about five feet wide, across which was a large, conspicuous, and powerful web. In the center of this web clung a huge and most remarkable spider, colored a vivid yellow and black. I watched it for a few moments while resting, and then touched the web, whereupon the spider began to swing, by raising and depressing its body, increasing its speed rapidly, until I could with difficulty see it. A moment later it disappeared almost entirely before my eyes. For half a minute the spider kept up this motion, then it slowly came to a standstill, having demonstrated that it could easily disappear from any bird enemy without running away. I have seen the daddy longlegs perform the same feat in California.
Fig. 176.—Spider with young upon its back.
The spiders which build webs, from plain geometrical traps to conelike affairs, are interesting; but the trapdoor spiders and those which dig burrows are among the wonderful artisans and engineers of the insect world. One of the most perfect doors, in hinge, fit, beauty of interior, finish, and quality of its outward defense is built by a spider (Fig. 177). In the illustration, the den and its trapdoor is shown, and in Figure 178 a sectional view of the same is seen; but the door is never found open, the spring or hinge being so devised as to remain closed. I have found many of these dens in southern California sometimes a foot or more in length. The spider is not the large one shown in the cut, which is a tarantula, but is very much smaller, though a large spider. The genera, Cteniza and Nemesia, are best known for their cunning and skill as builders. The California spider begins its den when very small, and I have found many the size of goose quills, with door complete, in the vicinity of a large den.
Fig. 177.—Tarantulas (Mygale) and the opening of a trapdoor den of another spider (Cteniza).