Fig. 9. “Face” of an Attid spider, shewing the anterior eyes and the chelicerae.
Our quarry is of small size, not more than a quarter of an inch long in the body, which resembles that of the wolf-spiders in build, the abdomen not rising above the level of the fore-body or cephalothorax. It is thickly clothed with short hairs—black, white, and grey—so arranged as to show oblique zebra-like stripes on either side of the abdomen. The legs are short and robust, very different from the long thin limbs of the garden-spider; especially strong are the fore-legs. The head is broad and square, with a high perpendicular forehead, but the most remarkable features are the eyes.
On the vertical front are four splendid eyes. The wolf-spider’s eyes were large, but these, in comparison, are immense, especially the median pair. Their axes are directed straight in front. Four other eyes are placed on the top of the head, far apart from each other, the more forward pair very small, the hind pair of moderate size. In some Attid spiders these great anterior eyes are wonderful objects under the microscope, deep sea-green in hue and fringed with coloured hairs. They form a veritable battery which the spider brings to bear upon the object of its chase. Human eyes, to match them in comparative size, would literally have to be as large as saucers!
If we are in luck, we soon descry a Salticus showing up boldly against the black surface of the fence, and to set ourselves to watch its antics attentively. One thing strikes us at once; it is quite at home on a perpendicular surface—nay, on the under side of a horizontal beam, for that matter. Now a garden-spider would have great difficulty in maintaining itself in such a position unless well supplied with silken lines to which to cling; evidently there is some difference in the structure of the feet of these spiders which may be worth investigating later on.
Also we notice some odd tricks of movement in the jumping spider; a curious way of exploring the surface on which it is working by a succession of short runs alternately with periods of absolute stillness as though on the qui vive; a noticeable freedom of movement between the fore- and the hind-bodies so that its battery of eyes may be directed to this side or that; sometimes an elevation of fore part as though for the purpose of obtaining a wider view.
We may have to wait long before we see it successful in the chase. It will often patiently explore a large area, testing the surface with its palps as it goes, without any obvious reward. It conscientiously searches all depressions and crannies, and, sometimes remains in them for a considerable time—perhaps to devour some minute creature which did not call into play its special methods of attack. At last it sights a small insect which has alighted on the fence a few inches away; we see it turn its head in that direction and remain motionless. Soon it begins to edge nearer in a stealthy manner, striving to approach its prey from behind, till, with a sudden spring, it pounces on its back. Not always is the spring successful; often the insect sees its peril at the last moment and takes to wing. But in this case, how does the spider avoid a fall? We see, what we had not noticed before, that it is anchored to the fence by a silken line; indeed all the time it has been hunting it has been trailing behind it an exceedingly fine thread of silk which it has attached at frequent intervals to the fence, so that it can check its fall at will in the case of accident. At the right angle, we may see the delicate filaments glistening in the sun over the surface of its explorations. The garden-spider entangles its prey in a web, the wolf-spider runs it down by sheer strength and speed, but the jumping spider stalks it like a Red Indian.
The actions of the spider make it quite evident that its power of sight is well developed. Mr and Mrs Peckham, whose remarkable observations on the mating habits of jumping spiders must presently be considered, established friendly relations with some of their captives which became so tame as to jump on their hands and take food from their fingers. They frequently induced them to jump from a finger of one hand to one of the other, gradually increasing the distance up to eight inches. They also twice observed a male chasing a female upon a table covered with jars, books and boxes. “The female would leap rapidly from one object to another, or would dart over the edge of a book or a box so as to be out of sight. In this position she would remain quiet for a few moments and then, creeping to the edge, would peer over to see if the male were still pursuing her. If he happened not to be hidden, she would seem to see him, even when ten or twelve inches away, and would quickly draw back.”
Moreover that they have the ability to discriminate colours has been shown by their behaviour when imprisoned in cages consisting of a series of communicating chambers each with a glass top of a different hue. They show a marked preference for the red chamber under these circumstances while the least attractive colour seems to be blue.
It has been known for a long time that the males of many kinds of birds—and especially of the more ornamental species—are accustomed to perform the most extraordinary antics in the presence of the female at the time of mating. The Peckhams made the unexpected discovery that precisely similar “love dances” took place in the case of the jumping spiders. Even the comparatively sober-coloured “zebra spider” performs a weird pas seul in courting its mate, but its display is feeble compared with that of some of the more ornate of the Attidae.