CHAPTER III.

LIFE IN THE OCEAN.

"See what a lovely shell, small and pure as a pearl, Frail, but a work divine, made so fairly well, With delicate spore and whorl, a miracle of design."

TENNYSON.

"The appearance of the open sea," says Frédol, from whose elegant work this chapter is chiefly compiled, "far from the shore--the boundless ocean--is to the man who loves to create a world of his own, in which he can freely exercise his thoughts, filled with sublime ideas of the Infinite. His searching eye rests upon the far-distant horizon. He sees there the ocean and the heavens meeting in a vapoury outline, where the stars ascend and descend, appear and disappear in their turn. Presently this everlasting change in nature awakens in him a vague feeling of that sadness 'which,' says Humboldt, 'lies at the root of all our heartfelt joys.'"

Emotions of another kind and equally serious are produced by the contemplation and study of the habits of the innumerable organized beings which inhabit the great deep. In fact, that immense expanse of water, which we call the sea, is no vast liquid desert; life dwells in its bosom as it does on dry land. Here this mystery reigns supreme in the midst of its expansions, luxuries, and agitations. It pleases the Creator. It is the most beautiful, the most brilliant, the noblest, and the most incomprehensible of His manifestations. Without life, the world would be as nothing. The beings endowed with it transmit it faithfully to other beings, their children, and their successors, which will be, like them, the depositaries of the same mysterious gift; the marvellous heritage thus traverses years and hundreds of years without losing its powers; the globe is redolent with the life which has been so bounteously distributed over it. In the words of Lamartine, "We know what produces life, but we know not what it is;" and this ignorance is perhaps the powerful attraction which provokes our curiosity and excites us to study.

Every living being is animated by two principles, between which a silent but incessant combat is being carried on--_life_, which assimilates, and _death_, which disintegrates. At first, life is all powerful--it lords it over matter; but its reign is limited. Beyond a certain point its vigour is gradually impaired; with old age it decays; and is finally extinguished with time, when the chemical and physical laws seize upon it, and its organization is destroyed. But the elements, though inert at first, are soon reanimated and occupied with a new life. Every plant, every animal is bound up with the past, and is part of the future, for every generation which starts into life is only the corollary upon that which expires, and the prelude of another which is about to be born. Life is the school of death; death is the foster-mother of life.

Life, however, does not always exhibit itself at the moment of its formation. It is visible later, and only after other phenomena. In order to develope itself, a suitable soil or other medium must be prepared, and other determinate physical and chemical conditions provided. The presence and diffusion of living beings are no chance products; they follow rigorously an order of law. Speaking of the higher forms of animal life, the Duke of Argyll says, in his able and satisfactory work, "The Reign of Law,"--"In all these there is an observed order in the most rigid scientific sense, that is, phenomena in uniform connexion and mutual relations which can be made, and are made, the basis of systematic classification. These classifications are imperfect, not because they are founded on ideal connexions where none exist, but only because they fail in representing adequately the subtle and pervading order which binds together all living things."

The knowledge of fossils has thrown great light upon the regular and progressive development of organization. The evolution of living beings seems to have commenced with the more rudimentary forms; the more ancient rocks, until very recently, had revealed no traces of life, and what has been revealed tends to confirm this view. In the Cambrian rocks of Bray Head, county Wicklow, the _Oldhamia_ is a zoophyte of the simplest organization, and the Rhizapods found near the bottom of the Azoic rocks of Canada are the lowest form of living types; and it is only in beds of comparatively recent formation that complex organization exists. Vegetables first show themselves, and even among these the simplest forms have priority. Animals afterwards appear, which, as we have seen, belong to the least perfect classes. The combinations of life, at first simple, have become more and more complex, until the creation of man, who may be considered the masterpiece of organization.

If we expose a certain quantity of pure water to the light and air in the spring, we should soon see it producing shades of a yellowish or greenish colour. These spots, examined through the microscope, reveal thousands of vegetable agglomerates. Presently thousands of animalcules appear, which swim about among the floating masses, nourishing themselves with its substance. Other animalcules then appear, which, in their turn, pursue and devour the first.

In short, life transforms inanimate into organized matter. Vegetables appear first, then come herbivorous animals, and then come the carnivorous. Life maintains life. The death of one gives food and development to others, for all are bound up together--all assist at the metamorphoses continually occurring in the organic as in the mineral world, the result being general and profound harmony--harmony always worthy of admiration. The Creator alone is unchangeable, omnipotent, and permanent; all else is transition.

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The inhabitants of the water are much more numerous than those of the solid earth. "Upon a surface less varied than we find on continents," says Humboldt, "the sea contains in its bosom an exuberance of life of which no other portion of the globe could give us any idea. It expands in the north as in the south; in the east as in the west. The seas, above all, abound with it; in the bosom of the deep, creatures corresponding and harmonizing with each other sport and play. Among these especially the naturalist finds instruction, and the philosopher subjects for meditation. The changes they undergo only impress upon our minds more and more a sentiment of thankfulness to the Author of the universe."

Yes, the ocean in its profoundest depths--its plains and its mountains, its valleys, its precipices, even in its ruins--is animated and embellished by innumerable organized beings. These are at first plants, solitary or social, erect or drooping, spreading into prairies, grouped in patches, or forming vast forests in the oceanic valleys. These submarine forests protect and nourish millions of animals which creep, which run, which swim, which sink into the sands, attach themselves to rocks, lodge themselves in crevices, which construct dwellings for themselves, which seek for or fly from each other, which pursue or fight, caress each other lovingly, or devour each other without pity. Charles Darwin truly remarks somewhere that our terrestrial forests do not maintain nearly so many living beings as those which swarm in the bosom of the sea. The ocean, which for man is the region of asphyxia and death, is for millions of animals the region of life and health: there is enjoyment for myriads in its waves; there is happiness on its banks; there is the blue above all.

* * * * *

The sea influences its numerous inhabitants, animal or vegetable, by its temperature, by its density, by its saltness, by its bitterness, by the never-ceasing agitation of its waves, and by the rapidity of its currents.

We have seen in preceding chapters that the sea only freezes under intense cold, and then only at the surface, and that at the depth of five hundred fathoms the same permanent temperature exists in all latitudes. On the other hand, it is agreed that the agitations produced by the most violent storms are never felt beyond the depth of twelve or thirteen fathoms. From this it follows that animals and vegetables, by descending more or less, according to the cold or disturbing movements, can always reach a medium which agrees with their constitutions.

The hosts of the sea are distinguished by a peculiar softness. Certain pelagic plants present only a very weak, feeble consistence; a great number are transformed by ebullition into a sort of jelly. The flesh of marine animals is more or less flaccid; many seem to consist of a diaphanous mucilage. The skeleton of the more perfect species is more or less flexible and cartilaginous; and it rarely attains, as to weight and consistency, the strength of bone exhibited by terrestrial vertebrate animals. Nevertheless, both the shells and coral produced in the bosom of the ocean are remarkable for their stony solidity. Among marine bodies, in short, we find at once the softest and hardest of organized substances.

The separation of organized beings, nourished by the ocean, is subjected to certain fixed laws. We never find on the coast, except by evident accident, the same species that we meet with far from the shore; nor on the surface, creatures whose habits lead them to hide in the depths of ocean. What immense varieties of size, shape, form, and colour, from the nearly invisible vegetation which serves to nourish the small zoophytes and mollusks, to the long, slender algæ of fifty--and even five hundred--yards in length! How vast the disparity between the microscopic infusoria and the gigantic whale!

"We find in the sea," says Lacepede, "unity and diversity, which constitute its beauty; grandeur and simplicity, which give it sublimity; puissance and immensity, which command our wonder."

In the following pages we shall figure and describe many inhabitants of the sea; but how many remain still to figure and describe! During more than two thousand years research has been multiplied, and succeeded by research without interruption. "But how vast the field," as Lamarck observes, "which Science has still to cultivate, in order to carry the knowledge already acquired to the degree of perfection of which it is susceptible!"

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"When the tide retires from the shore, the sea leaves upon the coast some few of the numberless beings which it bears in its bosom. In the first moments of its retreat, the naturalist may collect a crowd of substances, vegetable and animal, with their various characteristic colours and properties. The inhabitants of the coast find there their food, their commerce, and their occupations. At low water the nearest villages and hamlets send their contingents, old and young, men, women, and children, to the harvest. Some apply themselves to gathering the riband seaweed (_Zostera_), the membranous _Ulva_, the sombre brown _Fucus vesiculosus_, formerly a source of great wealth to the dwellers by the sea, being then much used in making kelp; others gather the small shells left on the sands; boys mount upon the rocks in search of whelks (_Buccinum_), mussels (_Mytilus_), detach limpets (_Patella_), and other edible marine animals, from the rocks to which they have attached themselves. On some coasts, shells, as _Mactra_, _Cytheria_, and _Bucardium_, are sought for their beauty. By turning the stones, or by sounding the crevices of the rocks with a hook at the end of a lath, polypes and calmars are sometimes surprised--sometimes even sea and conger eels, which have sought refuge there; while the pools, left here and there by the retiring tide, are dragged by nets of very small mesh, in which the smaller crustaceous mollusks and small fish are secured."

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In the Mediterranean and other inland seas, where the tide is almost inappreciable, there exist a great number of animals and vegetables belonging to the deep sea, which the waves or currents very rarely leave upon the sea shore. There are others so fugitive, or which attach themselves so firmly to the rocks, that we can watch them only in their habitats. It is necessary to study them floating on the surface of the waves, or in their mysterious retirements. Hence the necessity that naturalists should study the living productions of the salt water even in the bosom of the ocean, and not on the sea shore.

The means generally employed for this purpose is a drag-net, sounding-line, and other engines suitable for scraping the bottom, and breaking the harder rocks. In a voyage which Milne Edwards made to the coast of Sicily, he formed the idea of employing an apparatus invented by Colonel Paulin, which consisted of a metallic casque provided with a visor of glass, and consequently transparent, which fixed itself round the neck by means of a copper collar made water-tight by stuffing--a diving-bell, in short, in miniature. It communicated with an air-pump by means of a flexible tube. Four men were employed in serving the pump, two exercising it while the other two rested themselves. Other men held the extremity of a cord, which was passed over a pulley attached at a higher elevation, and enabled them to hoist up the diver with the necessary rapidity in emergencies. A vigilant observer held in his hand a small signal cord. The immersion of the diver was facilitated by heavy leaden shoes, which assisted him at the same time to maintain his vertical position at the bottom. M. Edwards made the descent with this apparatus in three fathoms water with perfect success. He was thus enabled to study, in their most hidden and most inaccessible retreats, the radiate animals, mollusks, crustaceans, and annelids, especially their larvæ and eggs, and by his descriptions to contribute most essentially to make known the functions, manners, and mode of development of certain inhabitants of the sea, whose sojourn and habits would seem to sequestrate them for ever from our observation.

Another and easier mode of studying the living creatures sheltered by the sea was first suggested by M. Charles des Moulins of Bordeaux, in 1830. The _aquarium_, which is charged with fresh or salt water, according to the beings it is intended to contain, serves the same purpose for the inhabitants of the deep which the aviary does for the birds of the air--cages of glass being used in place of iron wire or wicker-work, and water in place of atmospheric air.

When a globe is filled with fresh water, and with mollusks, crustaceans, or fishes, it is observed, after a few days, that the water loses its transparency and purity, and becomes slightly corrupt. It necessarily follows that the water must be changed from time to time. Changing the water, however, causes much suffering, and even death to the animals. Besides, the new water does not always present the same composition, the same aeration, or the same temperature with that which is replaced. To obviate this defect, and taking a leaf out of Nature's book, M. Moulins proposed to put into the vase a certain number of aquatic plants floating or submerged--duckweed, for example--which would act upon the water in a direction inverse to that of the animals inhabiting it. It is known that vegetables assimilate carbon, while decomposing the carbonic acid produced by the respiration of animals, thus disengaging the oxygen indispensable to animal life. In this simple manner was the necessary change of water obviated. The same happy idea has been successfully applied to salt water, and aquariums for salt-water plants and animals have been proposed on a great scale. That of the Zoological Gardens of Paris, in the Bois de Boulogne, inaugurated in 1861, is perhaps the largest in the world. It is a solid stone building of fifty yards in length by about twelve broad, presenting a range of forty reservoirs of Angers slate, running north and south. The reservoirs are nearly cubical, presenting in front the strong glass of Saint Gobain, which permits of the interior being seen. They are lighted from above; but the light is weak, greenish, uniform, and consequently mysterious and gloomy, giving a pretty exact imitation of the submarine light some fathoms down. Each reservoir contains about two hundred gallons of water. It is furnished with rocks disposed a little in the form of an amphitheatre, and in a picturesque manner. Upon the rocks various species of marine vegetables are planted. The bottom is of shingle, gravel, and sand, in order to give certain animals a sufficiently natural retreat.

Ten of these reservoirs are intended for marine animals. The water employed is never changed, but it is kept in continual agitation by circulation, produced by a current of water led from the great pipe which feeds the Bois de Boulogne. This water, being subjected to a strong pressure, compresses a certain portion of air, which, being permitted to act on a portion of the sea water contained in a closed cylinder placed below the level of the aquarium, makes it ascend, and enter with great force into a reservoir, into which it is thrown from a small jet. The sea water thus pressed absorbs a portion of the air, which is drawn with it into the reservoir. A tube placed in a corner of the reservoir receives the overflow, and conducts it into a closed carbon filter, whence it passes into a gravelly underground reservoir, returning again to the closed cylinder. The water is once more subjected to the pressure of air, and again ascends to the aquarium. The cylinder being underground, a temperature equal to about sixteen degrees Cent., which is nearly the uniform temperature of the ocean, is easily maintained. During winter, the aquarium is heated artificially.