parenthood among reptiles and fishes
a chapter on good fathers
“nature is a riddle without a definite solution to satisfy man’s curiosity.”—maurice maeterlinck.
in this chapter i shall consider certain examples, which i think are important to establish what we have learnt in our examination of the insects, that the parental impulse was not always fixed in the mother. among the reptiles and fishes the reverse is true, and what care is afforded to the young is given most frequently by the father.[16]
the bond between the mother and her young is directly dependent on their helplessness and the duration of time during which they require her care and attention. young reptiles are from birth independent, and, as a consequence, there has been no stimulus to develop maternal solicitude. between mother and offspring there are no ties of affection save in one or two exceptional cases.
young alligators, for example, are guarded by their mothers and owe more to her than they can ever know. she prepares a hatching nursery by scraping together a large mound of leaves, twigs, and fine earth, and upon this mound the eggs are placed about eight inches from the surface. then the mother digs a hole in the river bank, close by, and here she waits and watches to protect her children.
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a more advanced form of nursery building is practised by the tortoise, who prepares a sort of nest with considerable care, which she afterwards cunningly conceals. but when once the eggs are safe she shows no further interest in the safety of the nest.[17]
most snakes bury their eggs and then leave them. but a more enduring maternal interest is felt by the mother python; she coils her body around her future family and jealously guards them during the period of incubation, refusing all food and never leaving her duty.
a similar guardianship is shown to young crocodiles by their mothers. the home is prepared by digging a deep hole in the sand in which the eggs are placed, and during the period of incubation each mother sleeps in guard above her family. the naturalist voeltzkow, to prove the reality of one mother crocodile’s solicitude, built a fence around the nest just before the hatching time. each night on her return, the mother broke down the fence, though each time it was made stronger than the last. finally the nest was found to be deserted, and then it was discovered that this intelligent and persecuted mother had dug a hole beneath the fence and thence had led her brood away to safety.
it is impossible to admire sufficiently such a case as this one, where we see so clearly the driving power of maternal solicitude in quickening the intelligence of even the lowliest mothers. such cases are, however, few in number out of the 2,600 species of reptiles of whom the majority are unnatural parents.
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but again surprises await us. many frogs and toads, both the mothers and the fathers, show a really marked development of the familial instincts.[18] an illustration of this care is furnished by a large tree-frog (hyla faber) of brazil, commonly known as the ferreiro, “the smith,” from its strange voice resembling the mallet of a smith, slowly and regularly striking on a metal plate. this frog prepares a nursery in the shallow waters of the ponds, where a basin-shaped hollow is dug in the mud. the building is done by the mother, the material removed being used to form a wall, circular in shape, which is carried up to the surface of the water. in this cavity the eggs are placed, protected against the attacks of aquatic insects and fishes. a japanese tree frog (rhacophorus schlegelii) builds a similar nest, but here the mother lines the walls of her nursery with a secretion, a kind of milk food, from her own body, which by rapid movements of her feet is worked into a froth, and in the midst of this foamy mass the eggs are laid. more remarkable is the nursery building of the “wollunnkukk” frog (phyllomedusa hypochondrialis) of paraguay, whose habits were noted by dr. budgett during the exploration of the paraguayan chaco. “whilst sitting near the water’s edge he saw a female carrying a male upon her back. at last she climbed up the stem of a plant, reached out and caught hold of an overhanging leaf and climbed on to it. both then caught hold of its edges and held them together; and into the funnel thus formed the female poured her eggs, the male fertilising them as they passed. the jelly surrounding the eggs served as a cement to hold the edges of the leaves together. then, moving[82] up a little further, the process was repeated until the leaf was full, and about a hundred eggs had been enclosed.”[19]
a similar leaf nest is made by a brazilian frog, known as ihering’s frog (p. iheringí), while a home of more elaborate construction, in which several leaves are used, is prepared by savage’s leaf-frog (p. sauvagii).
it should be noted that in these cases the care of the parents is confined to the providing of a nursery; when once this is done the young are abandoned. but many frogs and toads do much more than this, and one or other parents, most often the father, guard their offspring with jealous care. a papuan frog-father, for instance, takes up the duties of a nurse; and when the eggs are laid, he sits upon them, holding the mass with both hands. and this vigil he keeps during the whole time while the young are undergoing growth, passing through the larval and tadpole stage.
we must own that such a father acts with singular devotion. it should be noted that seventeen eggs only are laid by the mother, a much smaller number than is common among the species where neither parent affords any kind of guardianship. this is what we should expect. nature has different ways of gaining the same end. life must be carried on, that is all that matters—an incessant renewal, an undying fresh beginning and unfolding of life. but a species is maintained sometimes by the prodigality of production and sometimes by the expenditure of care and sacrifice on the part of the parents. and here we find again a lesson waiting for us to learn. for it is hardly necessary to point out that the same facts are true of[83] human births; just as the family is unregulated or considered, do we find waste and many births with parental neglect in the first case and restricted births with parental devotion in the second. there seem to be no problems of the family that these pre-human parents have not had to face and solve.
but to return.
“the celebrated midwife toad (alytes obstetricans) gives us a further delightful example of the father nursing the young. the mother-toad lays her eggs attached to one another by threads so that they form a long chain. the father-toad then twines this chaplet of his wife’s eggs round and round his thighs. he has the strange appearance, it has been said, of a gentleman of the court of the time of james i, arrayed in puffed breeches. his devotion is very complete. after having encumbered himself with the coming family, he retreats to a hole in the ground. here he stays with admirable patience by day, stealing forth at night to feed, and to bathe his egg-burdened legs in dew or, when possible, in water. when his period of service is past and the young are ready for quitting the eggs, he seeks the water. here before long the young burst forth and swim away, whereupon the father, now free from his family duties, makes himself tidy (cleans himself of the remains of the eggs) and resumes his normal appearance.”
with some frogs, as, for example, in certain s. american and african species, the parents take up the burden of caring for the young only after they have reached the tadpole stage. the german naturalist brauer recently found in the seychelles islands a small frog (arthroleptis seychellensis) undertaking the guardianship of the young family. an adult frog (it is not stated whether it was[84] the father or the mother) was carrying nine tadpoles on its back, to which they were attached by a sucker on the belly. unfortunately, little is known of the habits of these frogs. it is believed that the eggs are laid in some shallow pool, and that later one or other parent returns to the nursery to take up the care of the young tadpoles.
a further remarkable case of care exercised by the father is that of darwin’s frog, the rhinoderma darwini, where the eggs are guarded in a great pouch under the throat, and opening by two slits into the mouth. during the courtship this pouch is used as a voice organ to charm the female, with sharp ringing notes like a bell. but the love-calls end with the birth of the family. there is now serious work to be accomplished. the father takes his wife’s eggs into his pouch, which now enlarges and extends backwards under the belly to the groin, and upwards on each side almost to the backbone. in the warm chamber thus formed, the tadpoles live until they become young frogs. they then make their way up through the doorways into their father’s mouth, and from that living nursery they swim out into the wide world.
well, what can we say of this case? we have heard of some animal fathers eating their progeny, but here the father’s mouth is turned into the hatching nursery. did i not tell you we should find very much to astonish us?
i could give many more examples of reptile parents whose family habits are more or less singular. there are the little-known “c?cilians,”[20] the strange, snakelike amphibians of s.e. asia and ceylon; where the mother, with her limbless body, yet contrives to dig a nursery for her eggs, which she jealously guards. i should like to write[85] of the families of the newts and salamanders, among whom the young are never completely abandoned, and whose parental habits present many features of interest. but to tell their life stories with all the vivid facts would take more space than i can allow to this one chapter of my book; and to give a bald record of their habits would afford little interest. i must, however, recount two instances of marked solicitude for the family, shown in each case by a different parent. take the case of a mother’s care first. a captive mother-salamander, of the species known as oregon plethodon, was placed with her eggs in a jar. she at once took possession of them, forming a loop around them with her tail. but, displeased with this unfamiliar house, she moved the eggs repeatedly from place to place till at length she was satisfied, and all the time using her tail for the work of transportation as a kind of maternal arm. in the second case the father most faithfully guards the eggs. a giant salamander in the zoological gardens of amsterdam kept watch over a clump of his wife’s eggs for a period of ten weeks. this careful father was seen every now and then to crawl among the eggs and lift them up, apparently for the purpose of aerating them.
from the foregoing examples it may, i think, be taken as established that among the reptiles there are many exemplary fathers. if the question is asked as to why in some species the care of the young is undertaken by the father and in others by the mother, i can only answer that i do not know. it would seem almost that at this early stage of life nature was making experiments as to which was the better parent. i would suggest that possibly such a reversal of the family duties was started by chance, possibly by the loss of the mother, or even by a specially energetic[86] father, and on being found successful the arrangement was continued and became fixed as a habit. i have not sufficient knowledge to know if this is possible. at any rate, it appears to be plain that, where for any reason the family duties are neglected by the mother, and where the maintenance of the species demands protection being given to the young, the father steps in to take the place of the mother; and by his care and devotion he becomes a truly constituent part—a working member—of the family group. i would ask you to keep this fixed in your attention, as i shall have to refer again and again to this fact that is here suggested.
what obtains among reptiles with regard to the father’s care for the young is even more frequent among fish-fathers. the common stickleback of our ponds and streams affords an admirable illustration of intelligent and devoted fatherhood. in this species the r?le of the two sexes is completely reversed; when once the eggs are deposited by the mother, the whole task of guarding them is undertaken by the father. his labours begin with the construction of a nest. this is formed of bits of weed, of fibre and dirt, collected with much care, the whole being held together by a cement produced by the clever father out of a secretion from his kidneys. having prepared the nursery, the stickleback sets out to find a wife heavy with eggs. his love choice apparently is decided by the capability of his spouse for her maternal function. by means of much persuasion and passionate courtship he woos her and induces her to deposit her burden of eggs in his nest.
i must wait to impress upon you the wonder of this fact. these love-antics of the stickleback, which are unique among fishes, would seem not to be exercised for the gratification[87] of male desire, but for the purpose of inducing the female to lay her eggs,—to do her part in giving him offspring. vainly do i ask myself the reason of this quite unusual sexual altruism. this is very extraordinary. the father woos the reluctant mother with passionate dances and his glad excitement is apparently intense. at this season the stickleback is transformed and glows with brilliant colours, his scales make silver look dim, his throat glows with flaming vermilion, he literally puts on a wedding garment of love.[21] and did i not fear being tedious by again waiting to point a moral, i should ask attention to this further proof given by the stickleback’s love joys to the truth which stands out in these life histories of pre-human parents. i mean this: the parent—the mother or the father—lives in the offspring. you will see how deep is the truth here. the parent is, after all, only the transitory custodian of the undying gift of life.
the conduct of the mother stickleback is in sharp contrast with the devotion of the stickleback father. at once, having rid herself of her eggs, her desire would seem to be to escape any further responsibilities. she forces her way out of the nest by wriggling through the wall opposite the entrance. true, by doing this she renders a service to the nursery, as she thereby furnishes a channel through which a continuous supply of fresh, cool water can be driven, thus keeping the eggs bathed. this is the only work the stickleback mother does for the family. the male, after the first laying, may persuade her to add still further to the deposit of eggs. sometimes, wearied with her one effort, she refuses. thus forced, the stickleback seeks a second wife, driven into polygamous conduct through his[88] desire for offspring. i know of no other case that is parallel with this. and the stickleback’s action has often been misrepresented. he is instanced as a polygamist; such is the fate that ever awaits self-sacrifice!
when the nest is full the father stickleback mounts guard over the entrance of the nursery for nearly a month, and he watches by day and by night, defending his precious charge against all comers.
and here another curious fact must be noted: the most dangerous assailants to the safety of the nursery are his own wives; these unnatural mothers would, if they were permitted, devour every single egg. is it this conduct of the female sticklebacks that explains the devotion of the male? again i do not know. certain it is, however, that the safety and care of the young is the stickleback father’s constant occupation—the duty to which he sacrifices his life. from time to time he changes the position of the eggs; he is a master in sanitation and keeps them constantly bathed with fresh water. this he does by driving a stream through the nest by means of a fanning motion of his breast, fins and tail. through all the hatching period he works with unceasing care.
when at length the fry are born, the father’s vigilance is even further taxed. the children, vigorous and venturesome, have to be watched by day and by night and protected. around and across and in every direction the father, as guardsman, continually swims. he drives off all comers with splendid courage. on one occasion a stickleback father was watched while his nest was attacked by two tench and a golden carp; he seized their fins and struck with all his might at their heads and eyes. truly the stickleback’s care of his children is extraordinary. his[89] vigilant eye is everywhere. if any members of the young brood stray too far from the nest for safety, he immediately swims after them, seizes them in his mouth, and brings them back to the safe playwater in the vicinity of the nursery. this continuous watchfulness lasts for about six days after the hatching.[22]
well, what do you think now of the common view of the parental instinct being stronger always in the mother than in the father? have we not been taking too much for granted and accepting theory for truth? in the light of our knowledge gained from these examples of the father’s extreme devotion, it seems impossible to refrain from thinking that the most intelligent and fit parent is the one who cares for the young. no doubt it is difficult, or even impossible, to decide the circumstances that have contributed to this strange result of the father taking the mother’s place in the family. we do not know whether these acts of his sacrifice to the children’s welfare imply the presence of the mind element—that is, whether they can be regarded as conscious as distinguished from unconscious adaptation, but this is altogether a separate matter and has nothing to do with the question we are considering.
fish display, according to romanes,[23] emotions of fear, pugnacity, social, sexual and parental feelings, anger, jealousy, play and curiosity. such emotions, he states, correspond with those that are distinctive of the psychology of a child of about four months.
in many diverse species there is clear evidence of some form of parental solicitude. the spotted goby, or pole-wing,[90] for instance, a fish which is found in the thames, is a nest-builder. an old cockle-shell is skilfully utilised to form the nursery. the shell is placed with its cavity turned downwards, beneath it the soil is removed and then the earth-walls are cemented together with a secretion from the skin of the parents. access to the nest is gained by a cylindrical tunnel, and the whole nursery is covered and concealed by loose sand. again it is the father who mounts guard over the eggs; his vigil lasts for about nine days.[24]
there are many instances of nursery building undertaken by fish parents. agassiz[25] records a case in which an elaborate nest formed of knotted weeds is made by a certain fish, known as chironectes. this rocking fish-cradle is carried by both parents and is a kind of arbour, affording protection and afterwards food for its living freight.[26] a remarkable nest is built by the american bow-fin (amia calva), found in the eastern states of north america. both the mother and the father work together to construct the nursery, which is formed by a large circular area cleared among the weedy shallows; these intelligent parents actually bite through the stems of all the plants that they cannot break or push aside. in the pool that is thus made the eggs are placed by the mother and fertilised by the father; the young develop with remarkable rapidity and hatch out in about eight days from time of laying. the family is then jealously guarded by the father, who herds the children—often numbering as many as a thousand individuals[27]—by circling around and above them in untiring[91] watchfulness. another remarkable nest is that of the eel-like gymnarchus of the nile; a huge floating nursery is made of grasses, measuring some two feet long and a foot broad. within this nest some thousand eggs are laid, and as soon as they are deposited by the mother, the father mounts guard, defending them, and afterwards the young, with great ferocity.
some fishes’ nests, like those made by the frogs, are constructed of foam. m. carbonnier gives the case of a chinese butterfly fish in his private aquarium in paris. the male fish constructed a large nest of froth, fifteen to eighteen centimetres horizontal diameter and ten to twelve centimetres high: this he did by a curious sucking and expelling air which formed the mucus in his mouth into a white foam. when the nest was thus prepared the female was induced to enter. i do not know whether the father’s duty was continued after this point.[28]
even where no nest is made, the eggs and young are sometimes guarded by one or other of the parents, but generally the father. schneider saw several fishes at the naples aquarium protecting their eggs; in one case the male mounted guard over a rock where the eggs were deposited, and swam with open mouth against all intruders. again, the butter-fish (pholis) of our coasts lays a mass of eggs, and around this future family the father coils[92] his body, just as does the python among the reptiles. some fishes, as for instance the cat-fishes (siluridae), have the curious habit of carrying the eggs in their mouth.
a further interesting case of paternal solicitude is furnished by the male fish of the common lump-sucker. the eggs are deposited in large clumps, and the father’s first care is to secure their proper oxygenation. this he does by pressing his head into the centre of each clump, an action which not only prevents the eggs from being too closely crowded, but serves also to press the spawn firmly into the crevices of the rock on which it is always laid. as soon as this is done this fish-father mounts guard over his family. all would-be enemies, such as star-fish and crabs, who make ceaseless efforts to rob the nursery, are driven off. the work of oxygenation is still carried on, and streams of fresh water, so necessary for the young lives, are driven by the careful father into the masses of the eggs. when the young appear new family duties await him, for the fry at once attach themselves to his body and are carried about by him.[29]
there are other instances where the young are attached to the body of the parent. sometimes it is the mother who gives this protection, and bears her eggs attached to the under surface of her body. the lophobranchiate fish incubate their eggs in pouches in the same way as some frogs, and they show elaborate parental feelings. when the young are hatched out, one or other parent, usually the father, carefully guards them, and the pouch then serves as a place of shelter or retreat from danger.
dr. reinhold hensel states of a little-known brazilian[93] fish (geophagus scymnophilus) that one of the parents—he does not say which—keeps careful guard over the family, which numbers from twenty to thirty. at a distance he watches his children. when alarmed for their safety, he takes a swift swim towards them, and they, as if at his word of command, collect around his mouth. suddenly, if the cause of alarm is not removed, the mouth is opened, and the whole family is engulfed. in an adult which was captured while thus laden, the young were seen to be crowded together in the mouth with their heads towards the gills. here the family is safe, and when the cause for alarm is passed, the youngsters are probably suddenly expelled from their living cavern. another extraordinary case is recorded by m. carbonnier, which certainly appears to show anxiety on the part of fish-fathers to have offspring. the males of the grotesque telescope-fish (a variety of carassius auratus) have the curious habit of acting as accoucheurs to the females. on one occasion three males were watched pursuing one mother heavy with spawn. they rolled her like a ball upon the ground for a distance of several metres, and this process they continued, without rest or relaxation, for two days. then the exhausted mother, who had been unable to recover her equilibrium for a moment, at last evacuated her eggs.
there is perpetual variety in the actions of even the lowliest parents. i might add many further examples more or less extraordinary, of the habits of fish and reptile mothers or fathers; but, even did the limit of my space permit this, it is not, i think, necessary: i have proved the existence low down in the scale of life of marked solicitude for the young, and shown that such care and sacrifice is shown frequently by the father.
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let me summarise now what we have learnt in this and the preceding chapter, so as to establish the lessons that seem to me may be taken from these pre-human parents. the diversity in the expression of the parental instincts must first be grasped. there is no fixed order, nor does there seem to be any continuity of development in this matter of care for the young. we have to give up quite the evolutionary idea of a certain and uninterrupted progress. throughout our inquiry we have been met with surprises. these things baffle our attempts to find an explanation. what is it that decides and develops the strong instinct of parenthood? a parent in a species that is lower in the scale will often have more parental feeling than a parent in a higher species. why, for instance, is the stickleback such a devoted father; more self-sacrificing than any other fish-father? and why is the stickleback mother without regard for her children? why among the dung-beetles is the same parental sacrifice shown by both parents? again, why is a nursery made in some cases and not in others? why are the young guarded sometimes by the mother and sometimes by the father? we may say that all this wide diversity in habits has arisen through adaptation; the circumstances that have conditioned the life of the species have been different, and this has necessarily caused variety in their behaviour. this is, of course, true, but does it really teach us very much? no sooner do we begin to apply our reasons to any particular case of family behaviour than we find ourselves at a loss. our reasoning suddenly breaks down, either because our knowledge is incomplete, or because one set of facts we possess seem to be contradicted by other facts of which we are equally sure.
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let us at once acknowledge our ignorance; there is much that cannot be explained.
if, however, we speculate at all on the matter, certain general ideas may be suggested. we are led to the view that when the father undertakes the care of the young, this reversal in the family duties must be primarily due to some failure on the part of the mother in performing the work in the nursery and home which customarily is hers. it is as if the father steps into her place in order that the species may escape the nemesis of elimination. the facts we have learnt are of no little importance. they tend to minimise, in the beginning of the family at least, the importance of the mother in relation to the young as compared with the importance of the father. it is this that i wish to establish.
and what we have learnt suggests the further interdependence, that does seem to exist among all species, between intelligence and good parenthood. fabre, out of his wisdom and as a result of his great knowledge, says that the duties of caring for the young are the supreme inspirers of the intellect. wherever we find devoted parents there also do we find lofty instincts. this is the second idea i ask you to accept. i think that we have proved its truth.
i may not stay here to point out the immense importance of these suggestions to the inquiry we are making as to the action of the maternal instinct, nor shall i pause to indicate the lessons that seem to me to await us from the curious transformation found in so many species in the duties of the two sexes. these considerations must wait until we know more. we have, i trust, extended somewhat, as well as rendered more exact, our knowledge on this complex and difficult question of motherhood. in the next two[96] chapters i shall endeavour to extend it still further by a brief consideration of certain striking habits i have met with of parenthood among the birds and higher animals.
i am well aware that there are many people who cannot bring themselves to believe in, or even listen without impatience to, any comparison between the conduct of animals and that which prevails among ourselves. it is absurd, they will say, to try to explain the conditions of human parenthood by references to animal parents. i have no hope of convincing, nor do i much desire to convince, those who thus object. i would merely advise them to leave out this section of my book altogether.
