IF you and I, my young friends, possessed the diving apparatus and the cunning of the little water spider, what an instructive excursion we might make together to the bottom of the ocean! Supposing we could escape the jaws and grinding teeth of alligators and crocodiles, and the wide open mouth of the monstrous whale, capable of engulfing at least a score of us at once; and the venomous fangs of sea serpents, which are as fatal as on land; what a world of wonders would everywhere meet our gaze!
There we should find mountains, valleys, and plains, just as on the surface of the earth. And as on the dry land there are stately trees and beautiful shrubs, and lovely grasses, and charming flowers, so on Ocean's bottom should we find what at first sight we should take for forests of verdure—plants, and flowers, and grasses. And just as we delight to gaze on a calm rural scene on a balmy summer's eve, the white fleecy sheep nibbling the sweet grass; the lambs frisking with all the activity and joy of childhood; the well-fed cattle, the very picture of quiet and contentment, dreamily lying down by the side of the still waters, so should we find the valleys and the mountain sides of the deep blue sea, full of life and activity.
There should we find swarms of beautiful fish, nibbling the rich verdure which everywhere covers the bottom of the sea, exactly like the sheep on our pastures.
I have said that at first sight we should suppose all we saw to be forests of rich verdure, but in fact we should soon discover that all was the result of animal life, not vegetable. The ancients believed that all these beautiful products of the ocean were purely vegetable; nor is it much more than a hundred years since it was clearly established that all the beautiful sights at the bottom of the ocean were composed of small living insects. If we were to wander sufficiently far, we should find our way blocked up by immense perpendicular mountains, some of them hundreds of miles in extent, and rising up to the very surface of the ocean. How astonished we should be to find that that vast mountain, the top of which was perhaps a great island with thousands of people living on it, was all formed by a tiny little insect, the largest of which is scarcely one-third of an inch in length!
Now it is about these little insects, and the wonderful works which they have accomplished, that I wish to tell you in this chapter.
This minute but wonderful little insect is called a Polype. Its make is very simple, and as some would say imperfect. They have no heart, no lungs, no liver, no intestines; they have neither head nor brains. Polypes are made up of a little straight bag, half transparent, open at one end and fashioned like a trumpet's mouth. Around the open end are six, sometimes eight or ten, moveable tentaculæ, or little arms. Thus the bag is the body, the opening is the mouth, the cavity is the stomach, and the tentaculæ are the arms. The Polype always seeks the light. It attaches itself to aquatic plants and other bodies by the closed end of its bag-like body. They cling to all kinds of shells and insects, and in this way they are carried in all directions; sometimes very slowly on the back of a lazy snail, sometimes as by express train under the sheath of a lively caddiss fly. Wherever they fix themselves they balance themselves easily and gracefully, stretching out in every direction their long slender arms. These arms are covered with what are called cilia—little hairs or appendages which protect, and perform other functions.
How do these Polypes live? When an unfortunate animalcule comes near enough for the stretched out arms to touch it, it is immediately seized and drawn to its mouth, the bag contracts, and the Polype digests its food in peace. When the repast is finished all that is useless is vomited out by the same mouth. A cunning little thing is this Polype. If a worm comes near, it is immediately garrotted by a thousand arms in every part of its body. Sometimes a little worm will seek to escape from the stomach, whereupon the ravisher plunges one of its arms into its stomach, and retains it there till its wriggling victim has been dissolved.
Like all life with what is called low organization, it is almost impossible to destroy it. If cut into a large number of pieces each piece will soon become a perfect Polype. If the arms are cut off they grow to perfect organizations. If the little bag be turned inside out, like the finger of a glove, it will still live on as if nothing had happened! The exterior skin which did respire, now digests, and the interior surface, which before carried on digestion, now performs the functions of breathing.
In every way these little creatures are most wonderful. Six or eight simple filaments supply the place of arms, feet, and lips, and all other organs of sense. When they are on the watch for their prey they perceive its approach and devour it. They fight among themselves; they thrust each other away, or chase each other. They bring up their progeny after their manner, and faithfully perform all their duties in that state to which they have been consigned. But this is as nothing compared with the wonderful part they have played in the building up of the globe we inhabit. When we come to the formation of coral reefs and islands, we shall find that these insignificant little Polypes are the builders which God, the great Architect, has employed to construct whole continents; and, indeed, to build up a great part of the earth on which we dwell.
But the Polype is only the beginning of an immense family. There is almost infinite variety, but all start from this point. Learned men have written large volumes about them, full of scientific names and beautiful engravings. To give all these, or a selection, would only puzzle my young reader; so as simply as possible I will describe how they develop, and multiply from this small beginning.
They multiply in this manner. The external surface of the digestive bag or body is seen to be covered with tubercles, which increase and lengthen, and gradually develop into miniature Polypes. When these are able to provide for themselves, the little tendon which connects them gives way, and in this manner the infant polype is born. More remarkable still, while the young Polype is still attached to the parent, upon its body a new little one is often observed to grow. This may give birth to a third, and the third even to a fourth! so that the parent carries at the same time, its son, its grandson, and its great grandson.
Now these I have been describing are fresh water Polypes, but those in the sea are substantially the same. There is, however, a remarkable peculiarity about some of them which produces amazing results. Some have soft gelatinous bodies altogether more like plants than animals. These, when they die, decompose, and leave no trace behind. Others are very different. The living creatures surround themselves with a hard substance something like the shells of certain insects.
The most remarkable of these is the well-known coral. Now the coral is not the living insect, but the deposit which this particular Polype produces. These coral Polypes increase with amazing rapidity; but instead of decomposing when they die, as others do, they become as hard as marble, and fresh ones continually grow, or are born on the old ones. In this way the great coral reefs and islands have been formed. But this I must reserve for another chapter.