a surprising relationship—the lion’s mane—the sabre-toothed tiger—some theories about origins—sea-lions in love—some strange ornaments—whales and weapons.
that the lion and the lamb could possibly have been derived from the same stock seems incredible: yet such is the case, though the pedigree is now well-nigh lost in the mists of a hoary antiquity. it is not surprising, then, that in their present-day garb they should show so little in common. nor is it strange that among their many points of divergence the one should differ so conspicuously from the other in the matter of secondary sexual characters. for when these are conspicuous among the ungulates they usually take the form of horns, of which the carnivores have no need, for the teeth and claws whereby they win their daily portion of meat make equally serviceable weapons of offence when turned against their own kind.
among the larger carnivora, the lion alone displays any obvious distinction between the sexes in the matter of ornament, and this in the form of the well-known mane. darwin, and later authorities, have regarded this 78as a shield to protect the great blood-vessels from injury during battles between rivals. but it is not very clear that this alone is sufficient to explain its presence, inasmuch as the tiger in this respect is defenceless. mr. f. c. selous long ago pointed out that the varying abundance of the mane is due to climatic causes. lions which live in districts where the nights are very cold, as in high table-lands, have large manes; those which occupy lower ground, where the nights are relatively warm, have but a scanty mane. it is clear, however, that the abundance of the mane is not determined by the need for warmth, otherwise it would have been as well developed in the female. rather we must regard a low temperature as conducive to the growth of long hair when a natural tendency to produce this is present.
there are few men who can claim to have so great a first-hand acquaintance with lions as mr. selous, and he has pointed out to me one significant fact which seems to show not only that the mane has not been developed to serve as a shield when fighting, but that fights between rival males must be rare. and this because of the absence of any evidence in the shape of scars on the skin. with claws so formidable as those of the lion, ugly wounds would certainly be made in any prolonged conflicts, for the skin of this animal is very thin.
in the now extinct sabre-toothed tiger the upper canines were of enormous length, and it is not improbable that they, on this account, exceeded the bounds of usefulness; that, while as weapons of offence they may have proved exceedingly effective, yet they hampered the animal when feeding. in many ways one is reminded by these weapons of the huge tusks of the walrus. these are 79blunt-pointed, and are said to be used very largely for digging up the large clams and other burrowing shell-fish on which this animal mainly feeds. they are also used as levers to drag the huge body out of the water on to the ice. as fighting weapons they are formidable, and the wounds they inflict are sometimes serious. the polygamous habits of this huge creature may account for the fact that they are so much larger in the males, wherein they may attain a length of thirty inches, and a weight of eight pounds a-piece.
in connection with the monstrous tusks of the sabre-toothed tiger there is a point which so far seems never to have attracted the attention it deserves. and this concerns two small flanges of bone which project from the lower border of the end of the lower jaw. in themselves they are unimportant: they lie, it is to be noticed, parallel with the points of the great upper teeth which descend on either side of them. their full significance is not apparent till we turn to the skull of another extinct animal of quite another type—the huge dinoceros, one of the ungulates. this animal was also armed with an enormous pair of tusks, which also, when the mouth was closed, descended on either side of a flange. in this case, however, the flange was developed to such an extent that its free edge descended to the level of the point of the tusk, thus affording it protection against injury. the really striking feature of this curious down-growth is not apparent till an attempt is made to explain its presence. what determined its growth? it seems to furnish us with another of the many instances which are to be found of the correlation of growth between unrelated parts, for there is apparently no traceable connection between the growth of this pair of teeth in 80the upper jaw and the development of the flanges of the lower border of the jaw which are embraced by these teeth. in the sabre-toothed tiger the inciting cause to this flange growth, whatever it may have been, seems to have been much weaker than in the case of dinoceros.
naturally one asks, can the whole thing be explained by the theory of kinetogenesis promulgated years ago by cope? that is to say, are these curious down-growths the result of a response to a stimulus set up in the lower jaw by constant lateral blows dealt by the tusks against the side of the jaw during the lateral movements of the jaw when feeding or ruminating? such movements in an ungulate would be frequent and constant: hence perhaps the more striking result. on account of the scissor-like action of the jaws in the sabre-tooth such lateral movements were far less extensive, and less powerful. but though this explanation sounds plausible, it presents many difficulties. in the first place it seems to commit one to the admission that the responses of the somatoplasm during the life of the individual are transmitted to the germ-plasm: that, in short, the characters acquired by the individual during its lifetime are transmitted to its offspring. and there are insuperable difficulties in the way of such a theory. yet, it must be admitted, it is no less difficult to believe that this correlation of growth is due solely to fortuitous variation, for one cannot really conceive of a variation of this kind taking place in two such different structures independently. such a conception would have been less difficult if the case of dinoceros alone were known to us. we could have supposed that, somehow, the lower jaw started to produce its flange just as the teeth began to develop an excess of growth which carried their points beyond the level of 81the jaw. but the sabre-tooth shows that the tusks had assumed a growth relatively exaggerated as in dinoceros, and yet the flange never attained to more than feeble development. we cannot rest content with the theory that the flange is due to the constant stimulus of blows struck against this region of the jaw during the lateral movements which take place when feeding. were these animals alive to-day it could be tested by extracting the tusks during infancy, when, the stimulus being removed, the flanges should not appear.
there are yet other aspects of the skull of dinoceros which may well be considered here. the first concerns the excessive armature of horns, there being no less than three pairs supported on massive bony cores; and the second the ridiculously small brain cavity which is proportionately smaller than that of any other known mammal, recent or fossil. this poverty of brain-power was probably one, if not the chief, factor among the causes which brought about the extinction of this strange beast. even more formidable horns were borne by the extinct arsinoetherium. but this animal did not display the double armature of horns and tusks.
among the carnivora monogamy is the rule, though the lion is occasionally polygamous. but the eared-seals (otaria), or sea-lions, and sea-bears afford a striking example of polygamous species and of the ferocity they display when sexually excited. these animals, moreover, are capable of the most astonishing powers of endurance and vitality, exceeding indeed that of all other mammals. since the habits of the northern fur-seal (otaria ursina) have been more carefully studied than those of any others, it may serve as a sample of the rest.
living for the greater part of the year in the open 82sea, the old bulls—animals of six or seven years old—are the first to seek the “rookeries,” or breeding grounds, taking up their territory a full month before the cows arrive. later, the younger bulls appear, and the more daring endeavour to force their way through the ranks of those who have already taken up positions. this often leads to fighting, but more usually nothing further than “bluffing” is indulged in, though it is commonly supposed that very severe engagements take place. this seems, however, to be only occasionally true. in due course, generally about the second week in june, the cows begin to arrive, at first in straggling numbers, but soon the main body puts in an appearance, and before the end of the month many thousands of both sexes are crowded along the foreshore. but yet, contrary to the generally accepted belief, no serious fighting takes place. the bulls quietly seize the females as they arrive. it would seem that the first arrival serves as a focus of attraction for all later comers landing in the vicinity. the bull holding the most advantageous post—that is to say, that nearest the best landing-place—starts the collection and, unintentionally, the distribution of the cows. having seized the first arrival, he places her by his side. as the later females arrive he gives each a most cordial welcome, and then proceeds to round up his harem. but soon he has more wives than he can continue to control. do what he will, he cannot be in two places at once; and thus it is that in rushing off to chastise some covetous neighbour, one or more bulls on the opposite side of his harem proceed to make captures from his horde. and this system of abduction goes on over the whole rookery till all the cows have been appropriated, leaving a crowd of envious bachelors in the background who have not yet developed either courage or strength to secure mates for themselves.
plate 13.
photo by new york zoological society, from “the living animals of the world.”
californian sea-lions, or eared seals.
the “bulls” of the eared seal are much larger than the “cows”; they have otherwise no very conspicuous “secondary sexual characters.”
[face page 82.
83
but within forty-eight hours of their landing the cows give birth to their “pups.” and it is for this purpose, and not for mating, that they come to land. within a few days of the birth, however, the females are “in use” again. this is the critical period in the life in the rookery. for the bulls now become frenzied with excitement and fight most viciously one with another, each hoping to possess himself of his opponent’s harem. each tries to seize the other by the fore flipper, and, failing in this, the fangs are buried in the back. they hold tenaciously, each trying to force the other to relax his hold; but commonly this vice-like grip is maintained till the skin gives way, leaving great bleeding rents. sometimes the contest rages till one or both is fatally wounded. often during such duels an idle bull, hitherto unable to secure a harem, will rush in and capture that of one of the combatants!
in the management of the harem the bull is an adept. whether he has five cows or fifty, he is, says dr. lucas, “master of the situation.” his will is law. not that it is always tamely accepted as such, but the result is the same. if a cow becomes restless, and moves about, a warning growl usually quiets her. if the movement is persisted in and an attempt to escape evident, the bull is up at once with a show of fierceness and in chase. he may simply strike her down with his open mouth. often in doing so his sharp canines tear a gash in her skin. he may even seize her in his mouth and deliberately throw her, or carry her back into the harem. if the cow thinks she has a chance to get away she may try to outrun him. if she miscalculates the distance he seizes her, after a few swift bounds, by the skin of the back, or by the hind flipper, and tosses her, often torn and bleeding, into the 84family circle. as a rule, however, she avoids this seizure by turning and facing her lord and master, and biting him in the breast and throat. but all to no purpose. in spite of her violent protests he pushes her backwards before him into the fold.
sometimes in her efforts to improve her position she runs up to, and is seized by, a rival bull. her lord speedily asserts his ownership by getting a grip wherever he can on the would-be truant. then begins a tug-of-war between the two bulls, during which the wretched victim of their rage may be torn in pieces. by the elimination in each generation of the more querulous and discontented, the peculiarly gentle and passive nature so characteristic of the females has been developed.
after the first ten days’ sojourn ashore the female is allowed to go to sea to feed, returning presently to suckle her young. the bull, on the other hand, can enjoy no such privilege. for three long months he must keep watch and ward fasting—at first, in order that he may retain his territory; later, that he may retain his harem. this fast, having regard to the loss of energy and blood which this strenuous period entails, is wonderful; for in the case of all other animals fasts are always associated with absolute rest and sleep. not so with the sea-lion; he arrives at the breeding-ground fat and well-liking, he leaves a starved and battered wreck.
the foregoing summary of the habits of these most interesting and much persecuted animals is taken from the exhaustive report of dr. f. a. lucas and mr. charles townsend. these two distinguished naturalists accompanied the united states contingent of the fur-seal international commission despatched in 1896–97 to 85inquire into the threatened extermination of these animals. major barrett hamilton accompanied the british contingent, and also made a report. and it is curious to note that on some points he is diametrically opposed, not only to the american naturalists, but to all other writers on this theme. he contends, for example, that “nothing could better illustrate the fact that it is the cows, and not the bulls, which have the real control of the harem-system.” he traced the rapid growth of two harems from four or five to as many as eighty cows. and he tells these were completely out of control and free to move about as they wished. “the bulls, in spite of all their bluster, had the flimsiest of nominal dominion, and the cows were always able to, and frequently did, leave the harems daily to dally with the cowless bulls on the outside. yet ... as long as they chose to sit massed together on the ground which had been appropriated by the two stronger bulls, no weaker rivals could approach to within ten yards of them. the master of the harem had no control over its occupants, but he was absolute lord of the ground on which they sat.” this is certainly curious, but more so is the fact that these females were allowed to return by the “cowless bulls” outside the charmed circle. later in the season he tells us he witnessed an even better illustration of this singular behaviour. at this time “the division of the cows into harems was a very unequal one, the smaller bull being only able to keep a very few cows, while the larger one claimed the greater part of the rookery. but the cows could pass over to the smaller bull’s ground as often as they liked; and he probably was father to a great many more of the pups born in 1898 than those of the half-dozen cows over whom he claimed control.” in regard to two 86other bulls in another cart of the island, there came a time when the inequality of the harems reached such a pitch, that the newly-arriving cows “had to lie in scattered groups outside the main mass, and thus permitted the weaker bulls to form new harems out of the reach of the two strong old bulls.” but perhaps the most singular feature of all was the indifference which one old bull displayed towards a little bachelor, permitting him to enjoy the most intimate relations with one of his cows without displaying the least sign of annoyance, as if he could scarcely regard one so young as a rival.
there is much evidence to show that the erotic side of the male-seal develops early. “i saw,” he says, “the little black pups acting to each other in a way that made it certain that their sexual feelings had already made themselves felt.” this one can well understand, for only animals of strong sexual tendencies could survive the strenuous life which the period of sexual activity entails.
the very different interpretation of the behaviour of these animals at this very important stage of their life-history must be due to the fact that different colonies were studied which were living, too, under somewhat different conditions. it seems clear, for example, that the landing of the females so graphically described by dr. lucas was a landing under exceptional circumstances, the master bulls having taken up positions at the only spot where access to the desired breeding quarters was to be found; while major barrett hamilton was probably fortunate in seeing phases which were wanting in the “rookeries” examined by dr. lucas. and both these observers again differ in the accounts they give of the life of such “rookeries” with those by mr. elliot, who explored these teeming colonies some years earlier when 87the number of animals forgathered there was far larger and the fighting, apparently in consequence, was far more severe.
in the matter of secondary sexual characters the most remarkable of the seal-tribe are those of the elephant seal and the bladder-nosed seal, and this because of the extraordinary development of inflatable tissue above the muzzle which these animals display. of their life-history we know little enough, and this despite the fact that for generations the elephant seal was mercilessly hunted and slain for the sake of its oil. millions were slaughtered during the last century, yet only scraps of information on the economy of the creatures has come down to us. all that is of any value, and especially in regard to the “courting” period, we owe to mr. charles townsend, of the new york aquarium, and this in regard to the northern species, macrorhinus angustirostris of guadelupe, though it may safely be inferred that the southern, antarctic species, m. leoninus, differs in no essential respects.
according to mr. townsend, the adult bull, having taken possession of his territory and formed a harem, is constantly called upon to wage duels for both with less fortunate rivals. and the severity of such combats was attested by the deep wounds and festering sores of the necks of these old warriors—which, at their maximum, attained in the days of their prosperity a length of nearly thirty feet and a girth of sixteen feet; but the last survivors of the race to-day seem rarely to exceed twenty-two feet. the weapons used in fighting are the canines, and the only armour they possess is that formed by the thickening of the skin of the neck, which forms a great massive shield, so that really dangerous wounds are rare. the great fleshy proboscis, the most vulnerable part, is carefully 88guarded by the upturned position of the head. the use of this trunk-like organ, which may attain a length of about fifteen inches, is not clear; it seems to serve mainly as an “ornament,” at times, too, furnishing a very definite indication as to the temper of its owner. while the animal is slowly moving its great carcase from place to place, this remarkable organ is relaxed, and pendent; but when fighting it is closely contracted so as to be out of harm’s way. whether it plays any useful part in the capture of food is not known; but it is probably much displayed during phases of sexual excitement. in young animals, it is significant to notice, as well as in the adult female this trunk is entirely wanting, which seems to suggest that this peculiar feature has only been recently acquired, the young and the adult female, as is the rule, standing nearer to the early forebears of this strange type. there is an enormous difference, it should be remarked, between the sexes in the matter of size, the female not attaining more than half the bulk of her lord. a further interesting point concerns the coloration of the young, which are black, while the adults are brown. doubtless this is connected with the requirements of the young, the black coat attracting more heat than the lighter-coloured coat of the adult.
as touching that curious creature, the crested, or hooded seal (cystophora cristatus), a native of the colder regions of the north atlantic. this animal is remarkable for the development, in the males alone, of a great crest or casque on the head, which is formed by a large inflatable air-sac over the ridge of the nose, and communicating with the nostrils. when fully inflated, it covers the head as far back as the eye. its purpose is a matter of conjecture. it seems to be inflated either when he animal is greatly excited, as when challenging rival 89males, or when threatened with danger from other causes, as when attacked by man. the males are exceedingly pugnacious, and fight with one another for the possession of females with great ferocity, such contests being accompanied by cries which can be heard for miles. from the difficulty which esquimaux and sealers find in killing the animal with clubs it certainly seems as if this strange wind-bag were more than merely ornamental.
plate 14.
photo copyright, w. p. pycraft.
elephant seal.
this is a young animal. note the great size of the eyes, and the general “seal-like” character of the head as compared with that of the adult.
photo by courtesy of charles haskins townsend, director of new york aquarium.
northern elephant seal.
adult male and female, and yearling. the male shows the enormously inflated snout.
[face page 88.
that those extraordinary creatures the cetacea—the whales and their kin—are derived from the same common stock as the typical carnivora there can nowadays be no doubt, widely as they have departed from their land-dwelling relatives in almost every possible feature of their organization. in the matter of their “courtship” we know nothing, but we may infer certain incidents in this critical period of their life-history from the peculiar nature of the secondary sexual characters which some species display. thus in the pilot whale (globicephalus) and the bottle-nose whale (hypero?don) the forehead, in the bulls, is enormously swollen by a mass of fibrous tissue so dense as to turn the blade of the sharpest knife, as i know well from attempts to dissect this region. now the only use, surely, for such a cushion is that of a battering-ram by rival males in charging one another, as rams and other horned animals will do. in the bottle-nose whale this cushion is backed up by an enormous mass of solid bone thrown up by the maxill?. the origin of this bony growth is interesting, for it appears first as a slight swelling in the rare species berardius; it is seen at a further stage of growth in the female “bottle-nose” (hypero?don), and attains its maximum in the male, where it stands unique. there are two other species which demand 90notice here. the first is layard’s beaked whale (mesoplodon); the second the narwhal. the former is the only vertebrate which in a wild state wears a muzzle! in this species the teeth have totally vanished save for a pair in the lower jaw, which are found towards the end of the jaw. these in the adult, or perhaps we should say senile, male grow upwards and inwards, finally meeting one another above the upper jaw, so as to make it impossible for the animal to open its mouth more than the fraction of an inch! surely here we have a secondary sexual character carried to an excess, and so proving not only disadvantageous to the animal, but positively disastrous, for it seems clear that so hampered the creature can feed only on the most minute forms of animal life, which could only be captured and swallowed with difficulty. it is true that the rorquals feed on excessively minute crustacea, but they are able to take in enormous quantities at a time, the “whalebone” serving the office of a sieve to prevent their escape. the mesoplodon has no such aids. one is tempted to believe that the skulls displaying this most curious feature are abnormal, comparable to those, say, of rabbits wherein the teeth have grown so excessively long as to close the mouth, on account of the displacement of the cutting surfaces by accident. but there is nothing to afford support to this view, and one must therefore fall back on the suggestion of senility.
the narwhal has long been celebrated for the enormous size of the canine teeth, the only teeth present in the jaws. as a rule, only one leaves its bony socket, the other, commonly the right, remaining as a mere vestige, seven or eight inches long within the skull. the protruding tooth, which is spirally fluted, may attain a length of nine feet. occasionally both teeth are developed, and in this 91case the spiral is the same, differing in a very striking manner from the spiral horns of ruminants, wherein one presents a right, the other left-handed spiral. but what purpose do these teeth serve? this question has never yet been definitely settled. some hold that it is used to break open breathing holes in the ice, for the animal lives in the far north: others that it is used as a spear in hunting prey. some aver that it serves as a weapon of offence, being used by rival males in their struggle for mates. scoresby, the explorer, indeed, says he has seen young males in mock-battle, fencing with these remarkable weapons. but until we have more satisfactory data, we must regard this armature of the narwhal as affording another instance of a secondary sexual character of doubtful value to its possessor.
