MODERN SCIENCE

Ashburton Guardian, Volume XLV, Issue 10163, 18 July 1924, Page 2

MODERN SCIENCE

THE DEPTHS OF THE SEA. " COLD, DARK, AND SILENT." Very different from all other haunts are the depths of the sea, including the floor of the abysses and the zones ,of water near the bottom. This haunt, forever unseen, occupies more than one-third of the earth's surface, and is thickly peopled. It camo into emphatic notice in connection with the mending of telegraph cables, but the results of the Challenger expedition in 1873-76 gave the first impressive picture of what' was practically a newworld. The average depth of the ocean is about two and a half miles; therefore, since many parts are relatively shallow, there must be enormous depths. A few of these, technically called deeps, are about six miles deep, in which Mount Everest would be engulfed. There is enormous, pressure in such depths] even at 2500 fathoms it is about two and a half tons dn the square inch. The temperature is on and off the freezing point of fresh water due to the continual sinking down of cold water from the poles, especially from the south. Apart from the fitful gleams of luminescent animals, there is utter darkness in the deep waters. The rays of sunlight are practically extinguished at 250 fathoms, although highly sensitive bromogelatine plates exposed at 500 fathoms have shown faint indications even at that depth. It is a world of

absolute calm and silence, and there is no scenery on-the floor. A deep, cold, dark, silent, monotonous world. While some parts of the floor of the abysses are more thickly peopled than others, there is no depth limit to the distribution of life. Wherever the long arm of the dredge has reached animals have been found—e.g., protozoa, sponges, corals, worms, starfishes, sea urchins, sea lilies, crustaceans, lamp shells, molluscs, ascidians, and fishes—a representative fauna. In the absence of light there can be no chlorophyll possessing; plants, and as the animals cannot all be eating one another there must be an extraneous source of food supply. This is found in the sinking down of minute organisms which are killed on the surface by changes of temperature and other causes. There seems to be no bacteria in the abysses, so there can be no rotting. Everything that sinks down, even the huge carcase of a whale, must be nibbled away by hungry animals and digested, or else, in the case of most bones, slowly dissolved away. Of the whale there are left only the ear bones; of the shark, his teeth.