Aquatic life

“ Upon being hatched the young are immediately led to water and the protection of thick and dank herbage. Here, too, food is abundant, which for these tiny things consists of the lowest forms of aquatic life. ”

“ All higher life, indeed, was originally aquatic; it is only just because ponds dry up in summer that the ancestors of beasts and birds and reptiles ever ventured on dry land, at first for a brief excursion, and afterwards for a permanence. ”

“ The pressure of competition has probably driven them into the water, where they descend as far as the lessening light-supply will allow. Some—presumably the earliest to take to an aquatic life—have all their relations to keep them company, the remote ancestor which adopted an aquatic habit being now represented by many species, or even by many genera. In other cases a terrestrial genus or order has few or only a single aquatic representative. ”

“ A Animal life had its beginning in the waters, and to this day the waters are the chief habitat of animals, especially of the lower forms. If we divide the animal kingdom into great leading types, the lowest of these groups, the Protozoa, includes only aquatic forms; the next, that of the coral animals and their allies, is also aquatic. So are all the species of the Sea Urchins and Star Fishes. Of the remaining groups, the Mollusks, the Crustaceans, and the Worms are dominantly aquatic, only a small proportion being air-breathers. ”

“ Aquatic in different ways, the differences depending on bodily relation to external temperature and on habit of life, are such animals on the one hand as take in air but live in water, and such on the other hand as take in water and are furnished with gills but go upon dry land and get their living there. ”

“ On the other hand, millions of aquatic animals may have been left quite dry, or buried in newly formed strata or thrown violently on the coasts, while their races may have been still preserved in more peaceful parts of the sea, whence they might again propagate and spread after the agitation of the water had ceased. ”

“ Admit a full glare of summer sun to the aquarium, and forth-with the water loses its pellucid fluidity, and becomes deeply tinged throughout of a dull green, as if some pigment had been dissolved in it. Instead of plants attached to stones and glass only, and animals that float unseen, the whole of the water is occupied by visible masses of animal and vegetable life; and, if the fishes suffer, it will be from undue heat, not from the addition to the element in which they live of this new mass of being. ”

“ A prawn or two, and a few minute star-fish, will make your aquarium complete; though you may add to it endlessly, as one glance at the salt-water tanks of the Zoological Gardens, and the strange and beautiful forms which they contain, will prove to you sufficiently.
You have two more enemies to guard against, dust, and heat. If the surface of the water becomes clogged with dust, the communication between it and the life-giving oxygen of the air is cut off ”

“ In this small space may be found animal and vegetable life of all kinds, anemonæ, lovely weeds, zoophytes, curious fish, sponges, shells, coral, and a hundred other things, all in such perfection and orderly wildness that no artificial aquarium [Pg 153] can ever hope to present, for they are made by hands, and can never vie with Nature in the formation of the wild and picturesque aspect of these rocky pools. ”

“ It is a life of swimming and climbing and resting after exertion. The skin seems to grow more sensitive to light and air, and the feel of water and the earth and leaves. Hour after hour one may float in the warm lagoons, conscious, in the whole body, of every shred and current of the multitudinous water, or diving under in a vain attempt to catch the radiant butterfly-coloured fish that flit in and out of the thousand windows of their gorgeous coral palaces. ”

“ Artificial water soon acquires the properties of natural sea water under the influence of these plants, which grow rapidly, and disseminate their spores throughout the tank, at the same time giving abundance of oxygen for the support of animal life. ”

“ The fisherman, meanwhile, stands in three feet of water, under the same summer’s sun, arbitrating in other cases between muckworm and shiner, amid the fragrance of water-lilies, mint, and pontederia, leading his life many rods from the dry land, within a pole’s length of where the larger fishes swim. Human life is to him very much like a river,
—“renning aie downward to the sea.” ”

“ Those principles, the knowledge of which was requisite to enable us thus to view the wonders of the ocean in their living state in an Aquarium, were not mastered at once, or by one man, or in one generation. The nature of certain relations between animal and vegetable life, upon which they are founded, was first advanced by Priestley, towards the close of the last century, who proved that plants give forth the oxygen necessary to animal life. ”

“ Balanced salt water aquariums are as easily made and kept as those of fresh water. Of course they must be filled with sea water fresh from the sea and all the inhabitants must be the young of various sea creatures, such as crabs, starfish, shrimps, and anemones. The plant life also must be the varieties that flourish in the sea, and where possible I believe in taking the pebbles and sand from a sea washed beach. ”

“ Study of a Balanced Aquarium.—Perhaps the best way for us to understand the interrelation between plants and animals is to study an aquarium in which plants and animals live and in which a balance has been established between the plant life on one side and animal life on the other. Aquaria containing green pond weeds, either floating or rooted, a few snails, some tiny animals known as water fleas, and a fish or two will, if kept near a light window, show this relation. ”

“ But in the salt as in the fresh water aquarium, vegetation is necessary for a healthful condition of the inmates. Here we see on a miniature scale that wonderful balance 204of organic forces which exists on the larger globe around us. The vegetation exhales the purifying oxygen, which renders the water fit for sustaining animal life ”

“ THE AQUARIUM. The successful treatment of aquatic plants and animals, in the confined space of a glass Aquarium, depends entirely upon the discovery that there exists in Nature a self-adjusting balance between the supply of oxygen created in water, with the quantity consumed by aquatic animals. ”

“ But artificial water is quite unsuited for animal life of any kind, until it has been brought into condition by means of growing weeds for eight or ten days, and for crustacea, star fishes, and fishes proper, it is not suitable till it has been in use for many months, and even then [60] some species lose their health in it, and at last perish. But for anemones of all kinds, many mollusks and crustaceans, and some other forms to be presently described, artificial water does well, and improves daily if properly managed. ”

“ The stream of water also passes but once along the gills of fish, as it is sooner deprived of its virtue; whereas the air is both received and ejected by the action of the lungs of land-animals. The whale seems to be an exception to the above, as he receives water and spouts it out again from an organ, which I suppose to be a respiratory one. As spring-water is nearly of the same degree of heat in all climates, the aquatic plants, which grow in rills or fountains, are found equally in the torrid, temperate, and frigid zones, as water-cress, water-parsnip, ranunculus, and many others. ”

“ For aquatic animals, water is their medium; without it they die. However the condition of the water is also important: dissolved salts and oxygen, currents and levels of light may be critical. Aquatic animals evolve to suit specific hydrological conditions: if these conditions change the animals may die. ”

“ A great deal that has been learned in modern times concerning the growth of the vegetation of the sea, of the habits of the animals, of their manner of life, their food and their growth, has been obtained from the chance of observation afforded by the various aquaria. ”

“ They swim about in companies of some hundreds, and frequent the still water of deep pools, will not take a bait, and are only seen when the water is clear. Then it is a delightful sight for any one to lie upon the bank of some ti-tree-fringed creek or pool, when the sun illumines the water and reveals the bottom, and watch a school of these fish swimming closely and very slowly together, passing over submerged logs, roots of trees or rocks, their scales of pure silver gleaming in the sunlight as they make a simultaneous side movement. ”

“ Thus the water, if the due proportion of its animal and vegetable tenants be observed, need never be changed. This is the true Aquarium, which aims to imitate the balance of Nature. By this balance the whole organic world is kept living and healthy. For animals are dependent upon the vegetable kingdom not only for all their food, but also for the purification of the air, which they all breathe, either in the atmosphere or in the water. ”

“ In a very small pond or tank the quantity of this kind of work is soon appreciable, and if we reflect on the amazing amount of water all over the globe, including seas and oceans, which swarm with infusoria, the total effect produced in a single year must seem considerable, even when compared with that portion of the earth's crust that is subject to alteration from all other causes put together. ”

“ The equilibrium between plant and animal life must be secured and maintained. Animals do not thrive in water where no plants are growing. Nature keeps plants and animals in the same pond, and we must follow her lead. The plants have three valuable functions in the Aquarium. ”

“ In other innumerable instances the apparently inexplicable profusion of fish in moist spots away from water is accounted for by the remarkable retention of vitality possessed by the mud-loving species, which emerge from torpidity into active life as soon as the waters return. ”

“ Thus the real Aquarium is a water-garden and a menagerie combined,—and aims to show life beneath the waters, both animal and vegetable, in all the domestic security of its native home, and in all the beauty, harmony, and nice adaptation of Nature herself. It is no sudden discovery, but the growth of a long and patient research by naturalists.
"What happens, when we put half a dozen gold-fish into a globe? The fishes gulp in water and expel it at the gills. As it passes through the gills, whatever free oxygen the water contains is absorbed, and carbonic acid given off in its place ”

“ But since this is a digestive or nutritive process, it follows that aquatic plants may derive much or all of their food from the water itself, or the carbon in it, in the same manner as the so-called air-plant, which grows without soil, does from the air. It is true, at any rate, that, in the fresh-water aquarium, the river and brook plants need no soil but pebbles; and that the marine plants have no proper root, but are attached by a sort of sucker or foot-stalk to stones and masses of rock. ”

“ I propose, therefore, that for a little while we consider the sea as an aquarium—a place adapted to the growth of animals and plants. Our subject is somewhat large, I must confess, but if we can see and understand how these things live and grow in the ocean we must be able to grow them in our parks, and possibly in our houses. For what Nature does on a grand scale may also be done in a small way; and principles that govern the successful growth of plants and animals in a bottle of sea water must be the same that govern the fauna and flora of the Pacific Ocean. ”

“ And now, having got the aquarium in order, comes the point how to keep it in order,—how to keep the creatures alive, and how to prevent the water from growing cloudy and thick. The main rule is to secure sunlight,--hot enough to raise the water to a temperature above that of the outer air,-- to remove all dirt and floating scum, and to furnish the tank on every cloudy day with a supply of air and with motion by means of a syringe. The creatures should never be fed in warm weather with any animal substance, its decay being certain to corrupt the water. ”

“ The secret herein involved, that animal and vegetable respirations counterbalance each other, has only of late years been discovered; yet it is apparent to any observing eye at the sea-shore; there we never meet with a rock-pool containing living animals, that is not more or less adorned with sea-weeds. ”

“ Marine testacea.—The aquatic animals and plants which inhabit an estuary are liable, like the trees and land animals which people the alluvial plains of a great river, to be swept from time to time far into the deep; for as a river is perpetually shifting its course, and undermining a portion of its banks with the forests which cover them, so the marine current alters its direction from time to time, and bears away the banks of sand and mud against which it turns its force. ”

“ Aquatic mammals which pass their lives entirely, or, for the greater part, in the water are, of course, subject to very different laws of distribution from those of the terrestrial forms. As regards aquatic mammals, land is of course an impassable barrier to their extension, and, subject to restrictions in certain cases, water offers them a free passage. ”