FAUNA OF THE DEEP SEA.

Waikato Times, Volume XLIII, Issue 3496, 20 November 1894, Page 7

FAUNA OF THE DEEP SEA.

Knowledge for July, in noticing' Sydney J, Hicksjii's new book on the " Fauna of the Deep Sea," has the following interesting remarks:—The deep sea seems to be absolutely dark, so far as sunlight is concerned, The temperature is only a taw degrees above the freezing' point, and the pressure is enormous, There is little or no movement of the water. The bottom is composed of a uniform soft mud, and there is no plant life. Dr. Hickson thinks that the darkness of the deep sea is probably relieved by the brilliant phosphorescence of many of the deep sea fish. If, he says, we may be allowed to compare the light of abysmal animals with that of surface forms, it is possible that some regioos of the deep sea may bG as brightly illuminated as a European street is at night—an illumination with many bright centres and many dark shadows, "but quite sufficient for a vertebrate eye to distinguish readily, and at a considerable distance, form and colour. To give an example of the extent to which the illumination duo to phosphorescent organs may reach, he quotes Sir Wyville Thomson as stating "that on leaving the Cape Verd Islands the sea was a perfect blaze of phosphoresThere was do moon, and although ttte. night was perfectly clear and stars shone brightly, the lustre of the heavens was fairly eclipsed by that of the sea. It was easy to read the smallest print, sitting in the after port of my cabin, the bows shed on either side rapidly widening wedges of radiance, so vivid as to throw the sails and rigging into distinct lights and shadows." All the abysmal creatures have eye 3, and the deep sea urustacea are uniformly uolouied red, though the suu's light does not give any perceptible illumination at a depth of even 300 fathoms. MM, Fol and Sarasin, experimenting with very sensitive broinogelatine plates, found that there was no reaction after 10 minutes' exposure at a depth of 400 metres on a sunny day in March. At the depth of 2500 fathoms the pressure is, rougly speaking, tons per squaro inch; that is to say, several times greater than the pressure exerted by the steam upon the pistons of our most powerful engines. Every animal at the bottom ot the Atlantic Ocean lives under apressuie about z5 times greater than will drive a railway train, What this enormous pressure is may be realised by the fact that thick glass tubes, filled with air and sealed up at either end, are

crushed to powder by tho water pressure before they reach a depth of 2000 fathoms.