Musical Lovers among Spiders and Scorpions—Colour among Spiders, and its uses—The Spiders’ Dance of Death—Spiders and Conjugal Bliss—How Pairing is accomplished—Scorpions in Love—Musical Crabs—Quarrelsome Fiddler-crabs—Crabs and Courtship in the Deep Sea—Amazons among Prawns—Brine-shrimps and Water-fleas—“Natural” v. “Sexual” Selection. It is a curious and significant fact that in the most brilliantly coloured of the Invertebrates—the Butterflies and Moths—” courtship” in the sense of “wooing” is extremely rarely met with; and this is quite contrary to what the Sexual Selection theory of Darwin demands, for, according to this, the colours are the result of that selection. On the other hand, Spiders, which are for the most part dull-coloured creatures, and the Scorpions, which are also dull-coloured, are commonly extraordinarily demonstrative during the early stages of “mate-hunger.” Some practise the form of instrumental music known as “stridulation,” others dance and indulge in other forms of posturing.
In the Spiders the stridulating apparatus is formed either between the limb-bearing portions of the body, or “cephalothorax,” and the abdomen; between the 237palps or leg-like feelers, and the jaws; or between these feelers and the front legs. But the construction is similar in all. In some Spiders the abdomen bears a horny collar, which is toothed, and these teeth, as the abdomen is raised and depressed, scrape against a number of delicate ridges on the thorax, or “chest,” which form a surface recalling that of a file. The grating of these opposing surfaces against one another produces shrill rasping or chirping sounds, which, in some cases at any rate, seem to be designed to inform the female of the presence of a suitor. Those who will, may examine this strange instrument for themselves if they will take the trouble to seek for it in one of our commonest English Spiders (Steatoda bipunctata). That it serves as a sexual excitant, or as an aid to mate-hunting, is indicated by the fact that it is found in males only, or in a very rudimentary condition in the female. There is a large Spider in Assam (Chilobrachys stridulatus) which produces a sound like the drawing of the back of a knife along the edge of a strong comb; and there are others which, by the friction of the feelers against the jaws, produce sounds like the buzzing of bees. One of the Wolf-spiders (Lycosa kochy) is known as the “purring” or “drumming” Spider from its custom, at mating-time, of rapidly drumming on dead leaves with its feelers. It is a wood-haunting species, and runs hither and thither over the ground as if searching for something, and pausing frequently to “purr.” This singular method of producing sound recalls that of the drumming of Woodpeckers on the hollow branches of trees, and similarly is produced without any special mechanism.
That the Scorpions should possess similar stridulating organs is only what we should expect, having regard to 238their kinship with the Spiders. In the great Rock scorpions of India and Africa the stridulating apparatus lies between the basal segment of the pincers and that of the first pair of legs, and consists of a set of tubercles and a cluster of curved, hair-tipped spines. During moments of excitement the pincers are waved up and down so that the spinules scrape against the tubercles, emitting a rustling sound, which has been compared to that produced by rubbing a stiff tooth-brush with one’s finger-nails. In the South African Opisthophthalmus the mechanism differs, consisting of leaf-like hairs placed on the inner surface of the jaws. But since both sexes possess these strange sound-producing mechanisms it has been suggested that their main, if not their only purpose, is to serve as a warning to enemies to keep their distance. Some of the great bird-eating Spiders (Aviculariid?) produce a kind of whistle; others, sounds like the dropping of shot upon a plate.
These stridulating contrivances present some curious and puzzling features. In the first place the sounds they produce are never loud to human ears; therein they differ from the shrill piercing sounds produced by like mechanism by the Crickets and Grasshoppers, though even with some of these the notes are, to us, inaudible. In the second, it has been suggested that where both sexes possess a stridulating apparatus its purpose is solely to warn off enemies, and this because the performers have no sense of hearing, and are thus, we presume, unaware of the sounds they produce. There is something unsatisfactory about this line of argument. There seems to be no evidence either that the sounds produced are loud enough to terrify an enemy, or that the performers are really deaf.
239In cases where the males alone stridulate it is always supposed that this “music” serves the purpose of a lure, or acts as an excitant, to the female, even though inaudible to human ears. But there are many people who are unable to hear the shrill squeal of our native bats. Yet no one doubts but that all bats hear it. The argument as to the absence of any sense of hearing in certain Spiders is based on their failure to respond to the vibrations of a tuning-fork, but this evidence is not conclusive. Neither is it safe to infer that the presence of stridulating organs in the adult and immature stages of both sexes, in some species, precludes their recognition as secondary sexual characters. They may serve the double purpose of sexual excitants and terrifying enemies, their motive being expressed by the quality of the sound as certainly as the timbre of the human voice may express rage or pleasure.
Neither Spiders nor Scorpions exhibit any very striking secondary sexual characters. As a rule the female is the larger, often strikingly so. Bright colours are rare, and are met with only among the Spiders, wherein sometimes the male, sometimes the female, is the more resplendent; where bright colours—apple-green, red and yellow—do occur, they seem rather to be of the type known as Anti-cryptic, or aggressive resemblance colours. That is to say, they are hues developed to deceive prey by reason of the likeness they afford the wearer to its surroundings. Thus, for example, one of our native Spiders (Tibellus oblongus) is straw-coloured, and has an elongated body, which is therefore seen with difficulty amid dry grass and rushes which are the haunts of the species. Misumena vatia, one of the Crab-spiders, resembles the flowers on which it is accustomed to lurk for its prey. It is of a 240variable hue, commonly yellow or pink, and a favoured lurking-place is near the blooms of the great mullein (Verbascum thapsus), where it seizes upon bees coming for honey. Exotic relatives of this species afford far more striking illustrations of this kind. One has a pink, three-lobed body which bears a striking likeness to a withered flower, and it exhales a sweet odour of jasmine. Insects attracted by the smell are thus readily pounced upon. Dr. Trimen, of Cape Town, describes a rose-red species which exactly matches an oleander flower, and to complete the deception the abdomen is marked with white. The same observer, approaching a bush of the yellow-flowered Senecio pubigera, noticed that two of the numerous butterflies settled upon it did not fly away with their companions. Each of these he found to be in the clutches of a spider whose remarkable resemblance to the flower lay not only in its colour, but in the attitude it assumed. “Holding on to the flower-stalk by the two hinder pairs of legs, it extended the two long front pairs upwards and laterally. In this position it was scarcely possible to believe that it was not a flower seen in profile, the rounded abdomen representing the central mass of florets, and the extended legs the ray florets; while to complete the illusion the femora of the front pair of legs, addressed to the thorax, have each a longitudinal red stripe which represents the ferruginous stripe on the sepals of the flower.” But more remarkable still is the case cited by my friend Dr. H. O. Forbes. This came under his notice while butterfly hunting in Java. The butterflies of the family Hesperid? have a habit of settling on the excreta of birds. Forbes noticed one on a leaf apparently enjoying a feast. Creeping up, he seized hold of this victim 241of a depraved taste and found it mysteriously held down. On further examination of this “excreta” he found that it was really a spider! Later, when in Sumatra, the same species once more in like manner deceived him. The deception is more than usually remarkable, for it is not due to the coloration of the body, but to what may almost be described as a diabolically ingenious display of intelligence. For the creature weaves upon a leaf a small white patch of web exactly resembling the fluid excrement of a bird sliding down the smooth surface of the leaf. Having completed this, the weaver lies on its back in the middle of the web holding on by the spines with which the legs are furnished. It then awaits its victim with the disengaged portions of the legs ready to close in a deadly embrace the moment the lure has done its work. Though somewhat in the nature of a digression, these facts show that colour often plays a vital part in well-being; though in the matter of courtship its r?le has probably been overestimated. Colour as an aid to “mate hunting “probably nowhere plays so important a part as was at one time believed. The Warblers among the birds, and the Spiders among more lowly animals, seem to demonstrate this fact.
The actual mating of Spiders, the act of coition, is peculiar, and demands notice, for the orgasm is not accomplished at the moment of the ejection of the sexual products. The male discharges the seminal fluid upon a small web woven for the purpose, and the liberated spermatozoa are then sucked up into a tube—the receptaculum seminis—which lies coiled up within a hollow bulb attached to the base of the last joint of the leg-like feeler, or “pedipalp” at the base of the head. The precious fluid is there stored and retained until the moment arrives when these palps can be thrust into die 242genital aperture of the female, and their contents discharged for the second and last time. This is the critical moment of the Spider’s life, and it is noteworthy that it should occur now, instead of at the moment of the discharge from the body. The ejection from the palpal organ is effected by means of a fibro-elastic bag, in its normal, collapsed, state spirally disposed round the base of the bulb which contains the sperm tube. Immediately preceding copulation this elastic bag or “h?matodocha” becomes turgid with blood, and it is probably the pressure thus exerted on its base which affords the final fury of desire without which, indeed, one might well imagine the necessary courage for copulation would never be raised, at any rate, in the case of some species.
Strange as these facts are, the nice adjustment of the instincts for their effectual performance is, by comparison, stranger still. By what subtle sense is the male Spider informed of the importance of the fertilizing fluid which escapes his body? What prompts him before its escape to prepare a web for its reception? What prompts him after its deposition to collect it within the palp till it shall be needed? The least defect in the instincts appertaining to these vitally important acts would mean the extinction of the race. We cannot suppose that the nature of their performance is in any way realized by the performer, and this makes their orderly execution the more wonderful.
Plate 34.
 
MALE ASTIA DISPLAYING BEFORE THE LESS BRILLIANT FEMALE.
 
From drawings, T. Carreras, in “Marvels of the Universe.”
MALE ICIUS DISPLAYING.
The “courtship” of the male spider takes the form of a “display” recalling that of birds. He commonly ends in being eaten by his mate.
[Face page 242.
Our knowledge of Spiders under the afflatus of sexual desire has been immensely increased by the long and patient observations of Mr. and Mrs. Peckham. The fact that their investigations were carried on with captive specimens, and therefore under artificial conditions both as to environment and the number of individuals placed 243together at one time, must not be lost sight of; nor must we forget that they worked under the firm conviction that the Sexual Selection theory of choice by the females was an indisputable fact. Wherever colour was present they looked for, and saw, evidence that the female appreciated such hues, though from their observations it would seem that dull-coloured species behaved as though they were suffused with resplendent hues. In the course of their studies the courtship of several species was investigated, but a summary of their results is all that can be given here. Saitis pulex formed the subject of one of their experiments. A male was placed in a box containing a mature female. “He saw her as she stood perfectly still, twelve inches away; the glance seemed to excite him and he moved towards her; when some four inches from her he stood still, and then began the most remarkable performance that an amorous male could offer to an admiring female. She eyed him eagerly, changing her position from time to time so that he might be always in view. He, raising his whole body on one side by straightening out the legs, and lowering it on the other by folding the first two pairs of legs up and under, leans so far over as to be in danger of losing his balance, which he only maintains by sidling rapidly towards the lowered side. The palpus, too, on this side was turned back to correspond to the direction of the legs nearest to it. He moved in a semicircle for about two inches, and then instantly reversed the position of the legs and circled in the opposite direction, gradually approaching nearer and nearer to the female. Now she dashes towards him, while he, raising his first pair of legs, extends them upwards and forwards as if to hold her off, but withal slowly retreats. Again and again he 244circles from side to side, she gazing towards him in a softer mood, evidently admiring the grace of his antics. This is repeated until we have counted one hundred and eleven circles made by the ardent little male. Now he approaches nearer and nearer, and when almost within reach whirls madly around and around her, she joining and whirling with him in a giddy maze. Again he falls back and resumes his semicircular motions with his body tilted over; she, all excitement, lowers her head and raises her body so that it is almost vertical; both draw nearer; she moves slowly under him, he crawling over her head, and the mating is accomplished. After they have paired once the preliminary courtship is not so long. On one occasion a female was the more eager of the two, but this is evidently very exceptional. The female always watches the antics of the male intently, but often refuses him in the end, even after dancing before her for a long time.”
Of another species—Epiblemum scenicum—they write: “The females seemed to have some difficulty in choosing from among the males, but after a decision has been reached and a male accepted, there appeared to be complete agreement.” A species of the genus Iritis, which seems to have baffled identification, was watched for hours under natural conditions as well as in confinement.” A dozen or more males, and about half as many females, were assembled together within the length of one of the rails. The males were rushing hither and thither, dancing opposite now one female, now another; often two males met each other, when a short passage of arms followed. They waved their first legs, sidled back and forth, and then rushed together and clinched, but quickly separated, 245neither being hurt, only to run off in search of fairer foes.”
These most patient observers seem to have been convinced that whenever Spiders possess vividly coloured areas on their bodies they are not only conscious of this fact, but desire to make the most of such splendour during the period of love-making. Thus they interpret the behaviour of a curiously ant-like Spider—Synageles picata—which has the first pair of legs especially thickened, flattened on the anterior surface, and of a highly iridescent steel-blue colour. As he approaches the female he pauses “every few moments to rock from side to side, and to bend his brilliant legs so that she may look full at them; ... he could not have chosen a better position than the one he took to make a display.” And similarly they interpret the movements of another species—Dendryphantes capitatus—which has a bronze-brown face, rendered conspicuous by snow-white bands. The attitude he assumes when sexually excited is one which seems, to them at any rate, to serve admirably to expose this feature to the watchful female. But he has other charms, and his “antics are repeated for a very long time, often for hours; when at last, the female, either won by his beauty or worn out by his persistence, accepts his addresses.” Habrocestum splendens—unhappily these creatures have no names in common speech—possesses an abdomen of a magnificent purplish red, and the attitude which he assumes at courtship they regard as one designed to display this to the full. Another case of quite remarkable interest is that of Astia vittata, because the males appear to be dimorphic. That is to say, they appear under two quite distinct forms, the one red, like the female; and the other black, with three tufts of hair just behind the head. The attitudes and 246the movements of courtship, it is significant to remark, are entirely different in the two varieties: the black form, assumed to be the later development, “is much the more lively of the two, and whenever the varieties were seen to compete for a female, the black one was successful.”
Professor Poulton, commenting on this particular case, contends that “it must be admitted that these facts afford the strongest support to the theory of Sexual Selection.” But do they? A further examination of the facts will probably show that the red “form” is but an immature example, and this being so, the difference in performance and the invariable success of Othello is at once accounted for. The fact that the “two forms pass into each other” and that the “tufts only occur in the fully developed niger form” is an additional reason for regarding the red form as immature.
Professor Poulton remarks: “When the males possess any special adornment they make a point of displaying them as fully as possible.” If this be so it seems to be a very foolhardy proceeding, akin to holding the proverbial “red rag” to a bull: for it is well known that the male Spider seeking a mate carries his life in his hands, at any rate in the case of many species. Mr. and Mrs. Peckham observed several instances of this remarkable sequel to Love’s embraces. In describing the female of Phidippus morsitans they remark that she was “a savage monster. The two males we provided for her had offered her only the merest civilities, when she leaped upon them and killed them.” The first pair of legs in the males of this species possess “special adornments” in the shape of long white hairs, and it was “while one of the males was waving these handsome 247legs over his head that he was seized by his mate and devoured.” Again, in the case of a male of Phidippus rufus, the display of his “ornaments” was his undoing, for he was “caught and eaten when he insisted upon showing off his fine points too persistently.” Thus the females seem to “select” the more resplendent males as much for eating as for mating! The ogre-like habits of the females in this regard, indeed, are almost without parallel in the animal kingdom.
Anyone who cares to take the trouble to watch the web of the large Garden Spider (Epeira diademata) may witness one of these connubial tragedies. In this species, the males are conspicuously smaller than the females, and it is possible that this disparity has been brought about by Sexual Selection, the largest and least active males having been exterminated. In some species the discrepancy in size is most striking, as for example in Nephila chrysogaster, the female of which measures two inches in length, the male not more than one-tenth of an inch, and less than one one-thousand-three-hundredth part of her weight.
The males, apparently, fully realize the perils which their amours may lead them into. They haunt the borders of the webs of unmated females, but exhibit a hesitating, irresolute manner. For hours they will linger near her, feeling the silken carpet cautiously with their legs, and apparently trying to ascertain the nature of the welcome likely to be extended to them. The odds are against them: for even if allowed to mate, unless they are extraordinarily agile in slipping away the moment they have attained their object, the chances are they will be slain and eaten!
Among some species, however, matters are otherwise: 248for the males of the genus Linyphia, for example, are generally to be found living peacefully with their consorts.
More rarely the male weaves a small nuptial tent, into which he partly leads and partly drives the female: though the “driving” would appear to be merely for form’s sake! The habits of the Cellar Spider (Tegenaria parietina), a long-legged species fairly common in the South of England, affords a yet further interesting and instructive contrast with the foregoing accounts. The pairing habits of this species have been studied by many observers, but perhaps the best account is that of Mr. F. M. Campbell. He found, to begin with, that in this species the tender ties of mating are at any rate rarely violated by the horrible aftermath of cannibalism so common a feature with so many other Spiders.
One or two illustrations from Mr. Campbell’s work must suffice. On one occasion he placed together a male and a female. For four days they took no notice of one another; then the female cast what proved to be her last skin, and within three hours after, the male began to show signs of interest in her presence—which is a fact of some significance, for not till then had she attained maturity. “After a few convulsive twitchings of the legs, the male pressed forwards, moving his palpi”—the leg like “feelers” on each side of the head which form the genital organs (page 241)—“up and down, when, as they touched the palpi of the female, the pair played with these organs like two friendly bees with their antenn?. After a few minutes the female raised herself, leaning a little on her left side, and the male crept forward until his head was under the breast of his mate, while his first pair of legs were resting upon hers. He now 249advanced his right palpus, leaning a little to the left and using the left palpus as part of his support. The right palpus was slightly twisted so as to bring the surface (containing the fertilizing germs) opposite the sexual organs of the female.... He now rapidly raised his palpus up and down for four or more seconds, and with such energy as to compel her to assume a vertical position. He then retired and again approached her, repeating the movements ... occasionally pausing before he withdrew his palpus.... At times he would leave the female for five minutes, and strut with straightened legs round the vase, wagging his abdomen. Now and then he would remain perfectly still with the palpus withdrawn, or play with the palpi of the female, while she seemed in a comatose state. He would then renew the union with undiminished vigour, appearing on each occasion less desirous of changing his position. I left them at 12–30 a.m. and returned at 7 a.m. The male was still using his right palpus. I saw no application of the left palpus, but have no doubt that it was employed during the night, as in other cases. I have not observed the pairing ever interrupted by a fresh collection of semen, although there is no reason to think this may not occur. The duration of pairing is long; but I am inclined to think it is more dependent on the difficulty in inserting the palpus than on sexual endurance. The impregnation appeared to take place when the male retained his palpi in front of the bursa copulatrices for about thirty seconds, which was frequently the case.” There are occasions, however, when a very different sequel attends this dalliance. In one instance, for example, Mr. Campbell placed a pair together, and at once the male began to pay his addresses. “Shortly 250afterwards he rapidly applied one of his palpi to the female ... apparently with her consent.” Five hours later “he charged her, tore away two legs ... and began to suck one, using the mandibles to hold the limb as a human being would a stick of asparagus.” It is not surprising to find she died an hour afterwards. An examination of her remains brought to light the fact that she was not mature. But this does not apparently explain the ferocity of her partner, for this investigator on two other occasions saw males similarly dismember their spouses an hour or so after impregnation. This horrid feast cannot have been prompted by hunger, for one of these males had, but a few hours previously, eaten a daddy-long-legs and two blow-flies. Only twice did this investigator see a female of this species drive away a male, and in each case immediately after union. “On the other hand,” he says, “I have kept an adult pair together from the 22nd of August to the 28th of October, and they lived in perfect amity. The male never ceased paying unrequited attentions except to feed.” It will have been remarked that the behaviour of this species in regard to mating differs conspicuously from the accounts of observations on other species, wherein the aggressive instincts are displayed by the female. Mr. Campbell, commenting on these facts, remarks that such conduct is just what one would expect from creatures which lead solitary lives, and must have “come to regard weaker forms of animal life as food, or as an inconvenience, if we except its young or its mate when in the act of pairing.” Instincts which are habitually practised throughout the greater port............