Science in Arcady

Fish As Fathers

Comparatively little is known as yet, even in this age of publicity, about the domestic arrangements and private life of fishes. Not that the creatures themselves shun the wiles of the interviewer, or are at all shy and retiring, as a matter of delicacy, about their family affairs; on the contrary, they display a striking lack of reticence in their native element, and are so far from pushing parental affection to a quixotic extreme that many of them, like the common rabbit immortalised by Mr. Squeers, 'frequently devour their own offspring.' But nature herself opposes certain obvious obstacles to the pursuit of knowledge in the great deep, which render it difficult for the ardent naturalist, however much he may be so disposed, to carry on his observations with the same facility as in the case of birds and quadrupeds. You can't drop in upon most fish, casually, in their own homes; and when you confine them in aquariums, where your opportunities of watching them through a sheet of plate-glass are considerably greater, most of the captives get huffy under the narrow restrictions of their prison life, and obstinately refuse to rear a brood of hereditary helots for the mere gratification of your scientific curiosity.

Still, by hook and by crook (especially the former), by observation here and experiment there, naturalists in the end have managed to piece together a considerable mass of curious and interesting information of an out-of-the-way sort about the domestic habits and manners of sundry piscine races. And, indeed, the morals of fish are far more varied and divergent than the uniform nature of the world they inhabit might lead an priori philosopher to imagine. To the eye of the mere casual observer every fish would seem at first sight to be a mere fish, and to differ but little in sentiments and ethical culture from all the rest of his remote cousins. But when one comes to look closer at their character and antecedents, it becomes evident at once that there is a deal of unsuspected originality and caprice about sharks and flat-fish. Instead of conforming throughout to a single plan, as the young, the gay, the giddy, and the thoughtless are too prone to conclude, fish are in reality as various and variable in their mode of life as any other great group in the animal kingdom. Monogamy and polygamy, socialism and individualism, the patriarchal and matriarchal types of government, the oviparous and viviparous methods of reproduction, perhaps even the dissidence of dissent and esoteric Buddhism, all alike are well represented in one family or another of this extremely eclectic and philosophically unprejudiced class of animals.

If you want a perfect model of domestic virtue, for example, where can you find it in higher perfection than in that exemplary and devoted father, the common great pipe-fish of the North Atlantic and the British Seas? This high-principled lophobranch is so careful of its callow and helpless young that it carries about the unhatched eggs with him under his own tail, in what scientific ichthyologists pleasantly describe as a subcaudal pouch or cutaneous receptacle. There they hatch out in perfect security, free from the dangers that beset the spawn and fry of so many other less tender-hearted kinds; and as soon as the little pipe-fish are big enough to look after themselves the sac divides spontaneously down the middle, and allows them to escape, to shift for themselves in the broad Atlantic. Even so, however, the juniors take care always to keep tolerably near that friendly shelter, and creep back into it again on any threat of danger, exactly as baby-kangaroos do into their mother's marsupium. The father-fish, in fact, has gone to the trouble and expense of developing out of his own tissues a membranous bag, on purpose to hold the eggs and young during the first stages of their embryonic evolution. This bag is formed by two folds of the skin, one of which grows out from each side of the body, the free margins being firmly glued together in the middle by a natural exudation, while the eggs are undergoing incubation, but opening once more in the middle to let the little fish out as soon as the process of hatching is fairly finished.

So curious a provision for the safety of the young in the pipe-fish may be compared to some extent, as I hinted above, with the pouch in which kangaroos and other marsupial animals carry their cubs after birth, till they have attained an age of complete independence. But the strangest part of it all is the fact that while in the kangaroo it is the mother who owns the pouch and takes care of the young, in the pipe-fish it is the father, on the contrary, who thus specially provides for the safety of his defenceless offspring. And what is odder still, this topsy-turvy arrangement (as it seems to us) is the common rule throughout the class of fishes. For the most part it must be candidly admitted by their warmest admirer, fish make very bad parents indeed. They lay their eggs anywhere on a suitable spot, and as soon as they have once deposited them, like the ostrich in Job, they go on their way rejoicing, and never bestow another passing thought upon their deserted progeny. But if ever a fish does take any pains in the education and social upbringing of its young, you're pretty sure to find on enquiry it's the father--not as one would naturally expect, the mother--who devotes his time and attention to the congenial task of hatching or feeding them. It is he who builds the nest, and sits upon the eggs, and nurses the young, and imparts moral instruction (with a snap of his jaw or a swish of his tail) to the bold, the truant, the cheeky, or the imprudent; while his unnatural spouse, well satisfied with her own part in having merely brought the helpless eggs into this world of sorrow, goes off on her own account in the giddy whirl of society, forgetful of the sacred claims of her wriggling offspring upon a mother's heart.

In the pipe-fish family, too, the ardent evolutionist can trace a whole series of instructive and illustrative gradations in the development of this instinct and the corresponding pouch-like structure among the male fish. With the least highly-evolved types, like the long-nosed pipe-fish of the English Channel, and many allied forms from European seas, there is no pouch at all, but the father of the family carries the eggs about with him, glued firmly on to the service of his abdomen by a natural mucus. In a somewhat more advanced tropical kind, the ridges of the abdomen are slightly dilated, so as to form an open groove, which loosely holds the eggs, though its edges do not meet in the middle as in the great pipe-fish. Then come yet other more progressive forms, like the great pipe-fish himself, where the folds meet so as to produce a complete sac, which opens at maturity, to let out its little inmates. And finally, in the common Mediterranean sea-horses, which you can pick up by dozens on the Lido at Venice, and a specimen of which exists in the dried form in every domestic museum, the pouch is permanently closed by coalescence of the edges, leaving a narrow opening in front, through which the small hippocampi creep out one by one as soon as they consider themselves capable of buffeting the waves of the Adriatic.

Fish that take much care of their offspring naturally don't need to produce eggs in the same reckless abundance as those dissipated kinds that leave their spawn exposed on the bare sandy bottom, at the mercy of every comer who chooses to take a bite at it. They can afford to lay a smaller number, and to make each individual egg much larger and richer in proportion than their rivals. This plan, of course, enables the young to begin life far better provided with muscles and fins than the tiny little fry which come out of the eggs of the improvident species. For example, the cod-fish lays nine million odd eggs; but anybody who has ever eaten fried cod's-roe must needs have noticed that each individual ovum was so very small as to be almost indistinguishable to the naked eye. Thousands of these infinitesimal specks are devoured before they hatch out by predaceous fish; thousands more of the young fry are swallowed alive during their helpless infancy by the enemies of their species. Imagine the very fractional amount of parental affection which each of the nine million must needs put up with! On the other hand, there is a paternally-minded group of cat-fish known as the genus Arius, of Ceylon, Australia, and other tropical parts, the males of which carry about the ova loose in their mouths, or rather in an enlargement of the pharynx, somewhat resembling the pelican's pouch; and the spouses of these very devoted sires lay accordingly only very few ova, all told, but each almost as big as a hedge-sparrow's egg--a wonderful contrast to the tiny mites of the cod-fish. To put it briefly, the greater the amount of protection afforded the eggs, the smaller the number and the larger the size. And conversely, the larger the size of the egg to start with, the better fitted to begin the battle of life is the young fish when first turned out on a cold world upon his own resources.

This is a general law, indeed, that runs through all nature, from London slums to the deep sea. Wasteful species produce many young, and take but little care of them when once produced. Economical species produce very few young, but start each individual well-equipped for its place in life and look after them closely till they can take care of themselves in the struggle for existence. And on the average, however many or however few the offspring to start with, just enough attain maturity in the long run to replace their parents in the next generation. Were it otherwise, the sea would soon become one solid mass of herring, cod, and mackerel.

These cat-fish, however, are not the only good fathers that carry their young (like woodcock) in their own mouths. A freshwater species of the Sea of Galilee, Chromis Andre by name (dedicated by science to the memory of that fisherman apostle, St. Andrew, who must often have netted them), has the same habit of hatching out its young in its own gullet: and here again it is the male fish upon whom this apparently maternal duty devolves, just as it is the male cassowary that sits upon the eggs of his unnatural mate, and the male emu that tends the nest, while the hen bird looks on superciliously and contents herself with exercising a general friendly supervision of the nursery department. I may add parenthetically that in most fish families the eggs are fertilised after they have been laid, instead of before, which no doubt accounts for the seeming anomaly.

Still, good mothers too may be found among fish, though far from frequently. One of the Guiana catfishes, known as Aspredo, very much resembles her countrywoman the Surinam toad in her nursery arrangements. Of course you know the Surinam toad--whom not to know argues yourself unknown--that curious creature that carries her eggs in little pits on her back, where the young hatch out and pass through their tadpole stage in a slimy fluid, emerging at last from the cells of this living honeycomb only when they have attained the full amphibian honours of four-legged maturity. Well, Aspredo among cat-fish manages her brood in much the same fashion; only she carries her eggs beneath her body instead of on her back like her amphibious rival. When spawning time approaches, and Aspredo's fancy lightly turns to thoughts of love, the lower side of her trunk begins to assume, by anticipation, a soft and spongy texture, honeycombed with pits, between which are arranged little spiky protuberances. After laying her eggs, the mother lies flat upon them on the river bottom, and presses them into the spongy skin, where they remain safely attached until they hatch out and begin to manage for themselves in life. It is curious that the only two creatures on earth which have hit out independently this original mode of providing for their offspring should both be citizens of Guiana, where the rivers and marshes must probably harbour some special danger to be thus avoided, not found in equal intensity in other fresh waters.

A prettily marked fish of the Indian Ocean, allied, though not very closely, to the pipe fishes, has also the distinction of handing over the young to the care of the mother instead of the father. Its name is Solenostoma (I regret that no more popular title exists), and it has a pouch, formed in this case by a pair of long broad fins, within which the eggs are attached by interlacing threads that push out from the body. Probably in this instance nutriment is actually provided through these threads for the use of the embryo, in which case we must regard the mechanism as very closely analogous indeed to that which obtains among mammals.

Some few fish, indeed, are truly viviparous; among them certain blennies and carps, in which the eggs hatch out entirely within the body of the mother. One of the most interesting of these divergent types is the common Californian and Mexican silver-fish, an inhabitant of the bays and inlets of sub-tropical America. Its chief peculiarity and title to fame lies in the extreme bigness of its young at birth. The full-grown fish runs to about ten inches in length, fisherman's scale, while the fry measure as much as three inches apiece; so that they lie, as Professor Seeley somewhat forcibly expresses it, 'packed in the body of the parent as close as herrings in a barrel.' This strange habit of retaining the eggs till after they have hatched out is not peculiar to fish among egg-laying animals, for the common little brown English lizard is similarly viviparous, though most of its relatives elsewhere deposit their eggs to be hatched by the heat of the sun in earth or sandbanks.

Mr. Hannibal Chollop, if I recollect aright, once shot an imprudent stranger for remarking in print that the ancient Athenians, that inferior race, had got ahead in their time of the modern Loco-foco ticket. But several kinds of fish have undoubtedly got ahead in this respect of the common reptilian ticket; for instead of leaving about their eggs anywhere on the loose to take care of themselves, they build a regular nest, like birds, and sit upon their eggs till the fry emerge from them. All the sticklebacks, for instance, are confirmed nest-builders: but here once more it is the male, not the female, who weaves the materials together and takes care of the eggs during their period of incubation. The receptacle itself is made of fibres of water-weeds or stalks of grass, and is open at both ends to let a current pass through. As soon as the lordly little polygamist has built it, he coaxes and allures his chosen mates into the entrance, one by one, to lay their eggs; and then when the nest is full, he mounts guard over them bravely, fanning them with his fins, and so keeping up a continual supply of oxygen which is necessary for the proper development of the embryo within. It takes a month's sitting before the young hatch out, and even after they appear, this excellent father (little Turk though he be, and savage warrior for the stocking of his harem) goes out attended by all his brood whenever he sallies forth for a morning constitutional in search of caddis-worms, which shows that there may be more good than we imagine, after all, in the domestic institutions even of people who don't agree with us.

The bullheads or miller's thumbs, those quaint big-headed beasts which divide with the sticklebacks the polite attentions of ingenious British youth, are also nest-builders, and the male fish are said to anxiously watch and protect their offspring during their undisciplined nonage. Equally domestic are the habits of those queer shapeless creatures, the marine lump-suckers, which fasten themselves on to rocks, like limpets, by their strange sucking disks, and defy all the efforts of enemy or fishermen to dislodge them by main force from their well-chosen position. The pretty little tropical walking-fish of the filuroid tribe--those fish out of water--carry the nest-making instinct a point further, for they go ashore boldly at the beginning of the rainy season in their native woods, and scoop out a hole in the beach as a place of safety, in which they make regular nests of leaves and other terrestrial materials to hold their eggs. Then father and mother take turns-about at looking after the hatching, and defend the spawn with great zeal and courage against all intruders.

I regret to say, however, there are other unprincipled fish which display their affection and care for their young in far more questionable and unpleasant manners. For instance, there is that uncanny creature that inserts its parasitic fry as a tiny egg inside the unsuspecting shells of mussels and cockles. Our fishermen are only too well acquainted, again, with one unpleasant marine lamprey, the hag or borer, so called because it lives parasitically upon other fishes, whose bodies it enters, and then slowly eats them up from within outward, till nothing at all is left of them but skin, scales, and skeleton. They are repulsive eel-shaped creatures, blind, soft, and slimy; their mouth consists of a hideous rasping sucker; and they pour out from the glands on their sides a copious mucus, which makes them as disagreeable to handle as they are unsightly to look at. Mackerel and cod are the hag's principal victims; but often the fisherman draws up a hag-eaten haddock on the end of his line, of which not a wrack remains but the hollow shell or bare outer simulacrum. As many as twenty of these disgusting parasites have sometimes been found within the body of a single cod-fish.

Yet see how carefully nature provides nevertheless for the due reproduction of even her most loathsome and revolting creations. The hag not only lays a small number of comparatively large and well-stored eggs, but also arranges for their success in life by supplying each with a bundle of threads at either end, every such thread terminating at last in a triple hook, like those with which we are so familiar in the case of adhesive fruits and seeds, like burrs or cleavers. By means of these barbed processes, the eggs attach themselves to living fishes; and the young borer, as soon as he emerges from his horny covering, makes his way at once into the body of his unconscious host, whom he proceeds by slow degrees to devour alive with relentless industry, from the intestines outward. This beautiful provision of nature enables the infant hag to start in life at once in very snug quarters upon a ready-made fish preserve. I understand, however, that cod-fish philosophers, actuated by purely personal and selfish conceptions of utility, refuse to admit the beauty or beneficence of this most satisfactory arrangement for the borer species.

Probably the best known of all fishes' eggs, however (with the solitary exception of the sturgeon's, commonly observed between brown bread and butter, under the name of caviare), are the queer leathery purse-shaped ova of the sharks, rays, skates, and dog-fishes. Everybody has picked them up on the seashore, where children know them as devil's purses and devil's wheelbarrows. Most of these queer eggs are oblong and quadrangular, with the four corners produced into a sort of handles or streamers, often ending in long tendrils, and useful for attaching them to corallines or seaweeds on the bed of the ocean. But it is worth noticing that in colour the egg-cases closely resemble the common wrack to which they are oftenest fastened; and as they wave up and down in the water with the dark mass around them, they must be almost indistinguishable from the wrack itself by the keenest-sighted of their enemies. This protective resemblance, coupled with the toughness and slipperiness of their leathery envelope or egg-shell, renders them almost perfectly secure from all evil-minded intruders. As a consequence, the dog-fish lay but very few eggs each season, and those few, large and well provided with nutriment for their spotted offspring. It is these purses, and those of the thornback and the edible skate, that we oftenest pick up on the English coast. The larger oceanic sharks are mostly viviparous.

In some few cases, indeed, among the shark and ray family, the mechanism for protection goes a step or two further than in these simple kinds. That well-known frequenter of Australian harbours, the Port Jackson shark, lays a pear-shaped egg, with a sort of spiral staircase of leathery ridges winding round it outside, Chinese pagoda wise, so that even if you bite it (I speak in the person of a predaceous fish) it eludes your teeth, and goes dodging off screw-fashion into the water beyond. There's no getting at this evasive body anywhere; when you think you have it, it wriggles away sideways, and refuses to give any hold for jaws or palate. In fact, a more slippery or guileful egg was never yet devised by nature's unconscious ingenuity. Then, again, the Antarctic chim** (so called from its very unprepossessing personal appearance) relies rather upon pure deception than upon mechanical means for the security of its eggs. The shell or case in this instance is prolonged at the edge into a kind of broad wing on either side, so that it exactly resembles one of the large flat leaves of the Antarctic fucus in whose midst it lurks. It forms the high-water mark, I fancy, of protective resemblance amongst eggs, for not only is the margin leaf-like in shape, but it is even gracefully waved and fringed with floating hairs, as is the fashion with the expanded fronds of so many among the gigantic far-southern sea-weeds.

A most curious and interesting set of phenomena are those which often occur when a group of fishes, once marine, take by practice to inhabiting freshwater rivers; or, vice-vers, when a freshwater kind, moved by an aspiration for more expansive surroundings, takes up its residence in the sea as a naturalised marine. Whenever such a change of address happens, it usually follows that the young fry cannot stand the conditions of the new home to which their ancestors were unaccustomed--we all know the ingrained conservatism of children--and so the parents are obliged once a year to undertake a pilgrimage to their original dwelling-place for the breeding season.

Extreme cases of terrestrial animals, once aquatic in habits, throw a flood of lurid light (as the newspapers say) upon the reason why this should be so. For example, frogs and toads develop from tadpoles, which in all essentials are true gill-breathing fish. It is, therefore, obvious that they cannot lay their eggs on dry land, where the tadpoles would be unable to find anything to breathe; so that even the driest and most tree-haunting toads must needs repair to the water once a year to deposit their spawn in its native surroundings. Once more, crabs pass their earlier larval stages as free-swimming crustaceans, somewhat shrimp-like in appearance, and as agile as fleas: it is only by gradual metamorphosis that they acquire their legs and claws and heavy pedestrian habits. Now there are certain kinds of crab, like the West Indian land-crabs (those dainty morsels whose image every epicure who has visited the Antilles still enshrines with regret in a warm corner of his heart), which have taken in adult life to walking bodily on shore, and visiting the summits of the highest mountains, like the fish of Deucalion's deluge in Horace. But once a year, as the land-crabs bask in the sun on St. Catherine's Peak or the Fern Walk, a strange instinctive longing comes over them automatically to return for a while to their native element; and, obedient to that inner monitor of their race, down they march in thousands, velut agmine facto, to lay their eggs at their leisure in Port Royal harbour. On the way, the n*****s catch them, all full of rich coral, waiting to be spawned; and Chloe or Dinah, serves them up hot, with breadcrumbs, in their own red shells, neatly nestling between the folds of a nice white napkin. The rest run away, and deposit their eggs in the sea, where the young hatch out, and pass their larval stage once more as free and active little swimming crustaceans.

Well, crabs, I need hardly explain in this age of enlightenment, are not fish; but their actions help to throw a side-light on the migratory instinct in salmon, eels, and so many other true fish which have changed with time their aboriginal habits. The salmon himself, for instance, is by descent a trout, and in the parr stage he is even now almost indistinguishable from many kinds of river-trout that never migrate seaward at all. But at some remote period, the ancestors of the true salmon took to going down to the great deep in search of food, and being large and active fish, found much more to eat in the salt water than ever they had discovered in their native streams. So they settled permanently in their new home, as far as their own lives went at least; though they found the tender young could not stand the brine that did no harm to the tougher constitutions of the elders. No doubt the change was made gradually, a bit at a time, through the brackish water, the species getting further and further seaward down bays and estuaries with successive generations, but always returning to spawn in its native river, as all well-behaved salmon do to the present moment. At last, the habit hardened into an organic instinct, and nowadays the young salmon hatch out like their fathers as parr in fresh water, then go to the sea in the grilse stage and grow enormously, and finally return as full-grown salmon to spawn and breed in their particular birthplace.

Exactly the opposite fate has happened to the eels. The salmonoids as a family are freshwater fish, and by far the greater number of kinds--trout, char, whitefish, grayling, pollan, vendace, gwyniad, and so forth--are inhabitants of lakes, steams, ponds, and rivers, only a very small number having taken permanently or temporarily to a marine residence. But the eels, as a family, are a saltwater group, most of their allies, like the congers and mur***, being exclusively confined to the sea, and only a very small number of aberrant types having ever taken to invading inland waters. If the life-history of the salmon, however, has given rise to as much controversy as the Mar peerage, the life-history of the eel is a complete mystery. To begin with, nobody has ever so much as distinguished between male and female eels; except microscopically, eels have never been seen in the act of spawning, nor observed anywhere with mature eggs. The ova themselves are wholly unknown: the mode of their production is a dead secret. All we know is this: that eels never reproduce in fresh water; that a certain number of adults descend the rivers to the sea, irregularly, during the winter months; and that some of these must presumably spawn with the utmost circumspection in brackish water or in the deep sea, for in the course of the summer myriads of young eels, commonly called grigs, and proverbial for their merriment, ascend the rivers in enormous bodies, and enter every smaller or larger tributary.

If we know little about the paternity and maternity of eels, we know a great deal about their childhood and youth, or, to speak more eelishly, their grigginess and elverhood. The young grigs, when they do make their appearance, leave us in no doubt at all about their presence or their reality. They wriggle up weirs, walls, and floodgates; they force there way bodily through c****s and apertures; they find out every drain, pipe, or conduit in a given plane rectilinear figure; and when all other spots have been fully occupied, they take to dry land, like veritable snakes, and cut straight across country for the nearest lake, pond, or ornamental waters.

These swarms or migrations are known to farmers as eel-fairs; but the word ought more properly to be written eel-fares, as the eels then fare or travel up the streams to their permanent quarters. A great many eels, however, never migrate seaward at all, and never seem to attain to years of s****l maturity. They merely bury themselves under stones in winter, and live and die as celibates in their inland retreats. So very terrestrial do they become, indeed, that eels have been taken with rats or field-mice undigested in their stomachs.

The sturgeon is another more or less migratory fish, originally (like the salmon) of freshwater habits, but now partially marine, which ascends its parent stream for spawning during the summer season. Incredible quantities are caught for caviare in the great Russian rivers. At one point on the Volga, a hundred thousand people collect in spring for the fishery, and work by relays, day and night continuously, as long as the sturgeons are going up stream. On some of the tributaries, when fishing is intermitted for a single day, the sturgeons have been known to completely fill a river 360 feet wide, so that the backs of the uppermost fish were pushed out of the water. (I take this statement, not from the 'Arabian Nights,' as the scoffer might imagine, but from that most respectable authority, Professor Seeley.) Still, in spite of the enormous quantity killed, there is no danger of any falling off in the supply for the future, for every fish lays from two to three million eggs, each of which, as caviare eaters well know, is quite big enough to be distinctly seen with the naked eye in the finished product. The best caviare is simply bottled exactly as found, with the addition merely of a little salt. No man of taste can pretend to like the nasty sun-dried sort, in which the individual eggs are reduced to a kind of black pulp, and pressed hard with the feet into doubtful barrels.

In conclusion, let me add one word of warning as to certain popular errors about the young fry of sundry well-known species. Nothing is more common than to hear it asserted that sprats are only immature herring. This is a complete mistake. Believe it not. Sprats are a very distinct species of the herring genus, and they never grow much bigger than when they appear, broch*, at table. The largest adult sprat measures only six inches, while full-grown herring may attain as much as fifteen. Moreover, herring have teeth on the palate, always wanting in sprats, by which means the species may be readily distinguished at all ages. When in doubt, therefore, do not play trumps, but examine the palate. On the other hand, whitebait, long supposed to be a distinct species, has now been proved by Dr. G*****, the greatest of ichthyologists, to consist chiefly of the fry or young of herring. To complete our discomfiture, the same eminent authority has also shown that the pilchard and the sardine, which we thought so unlike, are one and the same fish, called by different names according as he is caught off the Cornish coast or in Breton, Portuguese, or Mediterranean waters. Such aliases are by no means uncommon among his class. To say the plain truth, fish are the most variable and ill-defined of animals; they differ so much in different habitats, so many hybrids occur between them, and varieties merge so readily by imperceptible stages into one another, that only an expert can decide in doubtful cases--and every expert carefully reverses the last man's opinion. Let us at least be thankful that whitebait by any other name would eat as nice; that science has not a single whisper to breathe against their connection with lemon; and that whether they are really the young of Clupea harengus or not, the supply at Billingsgate shows no symptom of falling short of the demand.