BY REV. THEODORE WOOD
INot very many years ago, it was supposed that life was altogether absent in the deeper parts of the sea. Now we know that this is not the case. Expeditions of scientific men have been sent out by different countries to dredge in very deep water, and their discoveries have clearly proved that fishes, mollusks1, crustaceans2, and even the soft-bodied sea anemones are capable of living more than three miles below the surface of the ocean.
To those profound depths no ray of sunlight can ever penetrate; and, though many of the deep-sea creatures possess eyes, we might think that they would never have an opportunity of using them. For to see in absolute darkness is impossible. We often say, it is true, that cats can see in the dark; but the fact is, that even on the darkest night there is always some little light, while a cat"s eyes are made in such a way that they can take in many more rays of light than our eyes. The animal, consequently, is able to see clearly when we ourselves can scarcely see at all. But at the bottom of the sea the darkness is almost complete, so that1Mollusks: animals covered with shells, such as cuttlefish and snails.
2Crustaceans: shellfish, such as lobsters and crabs, so called from the crustlike shell with which they are covered.
to the creatures of the deep, eyes would seem useless.
But that is not all. The bodies of these animals must be able to resist an almost inconceivable pressure. We ourselves, living at the bottom of the ocean of air, have to endure an atmospheric pressure of fifteen pounds to the square inch; that is to say, the weight of the air above us is so great, that it presses upon every part of our bodies with exactly that degree of force.
If, however, we dive under water, we have to bear the pressure of the water in addition to this; and as water is very much heavier than air, this pressure soon becomes so great that even a trained diver cannot descend to a depth of more than fifty fathoms.
Now, fishes and other animals have been found at a depth of over three miles. This means that they have to endure, upon every square inch of their bodies, a pressure of rather more than two tons and a half, or five-and-twenty times the force required to drive a railway train at a high rate of speed. It would seem impossible that any living creature could resist a pressure so tremendous.
Nevertheless, the inhabitants of the deep sea are somewhat numerous. More than twenty kinds of fishes alone have been found at a depth of more than two thousand fathoms; and, as only a very small portion of the ocean-bed has as yet been explored, we may feel quite certain that a great many more still remain to be discovered.
Strange to say, although these fishes live at depths so profound, they are not entirely destitute of light. The sun"srays cannot reach them, it is true; but, on the other band, they are very frequently themselves luminous. In some cases their whole bodies glow with phosphorescent1 light, which seems to issue from the slime with which the skin is covered; in others the light proceeds from a double row of curious eyelike organs, which run along the sides from the head almost to the tail. Thus these animals are independent of sunlight. They are their own lightgivers. They dwell in the midst of absolute darkness, and yet are always able to see.
One of these luminous fishes uses its light for a very remarkable purpose.
It is a creature of prey, feeding entirely upon other fishes; and its appetite is so voracious2 that it always appears to be hungry. Yet it is so slow in its movements that it is quite unable to pursue and overtake its victims. Nature, however, has provided it with an apparatus which is admirably adapted for luring3 those victims to their fate. The first or front fin of the back is wanting; but its place is taken by a long, slender spine, the base of which is fastened to the bones of the back by a kind of ring-and-staple attachment, so that it can be freely moved in any5 direction. At the end of this spine is a flattened tip, which is highly luminous.
Now, fishes are extremely inquisitive creatures. Any strange object invariably rouses their curiosity, and they are especially attracted by anything that glitters or shines. Anglers, for example1Phosphorescent: shining with a light like that of phosphorus, a natural light- giving substance.
2Voracious: greedy; gluttonous. 3 Luring: attracting.
often catch pike and other fishes by means of a spoon bait, which is simply a piece of polished tin armed with hooks, and fastened to the line in such a manner that it revolves rapidly when drawn through the water. Now, the luminous spine of this deep-sea fish is simply a natural spoon bait, and all that its owner has to do when it feels hungry is to dangle it up and down in front of its mouth. All the small fishes in the neighborhood are sure to come and examine it, only to be snapped up by the jaws of their foe as soon as they venture within its reach.
How successful this remarkable fish is in its angling, may be judged from the number of victims sometimes captured by its near relation, the fishing frog, which is found not uncommonly in shallower water. In the stomach of one of these fishes which was killed and opened immediately after capture, were found no fewer than seventy-five herrings, while another had swallowed twenty-five flounders.
