Motherhood and the Relationships of the Sexes

by C. Gasquoine Hartley

In many diverse species there is clear evidence of some form of parental solicitude. The spotted goby, or pole-wing, 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 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 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 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.

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.