October 27, 2009 | Posted by maneerat
In great contrast to the narrow, crowded, difficult conditions of the shore-haunt (littoral area) are the spacious, bountiful, and relatively easygoing conditions of the open sea (pelagic area), which means the well-lighted surface waters quite away from land. Many small organisms have their maximum abundance at about fifty fathoms, so that the word “surface” is to be taken generously. The light becomes very dim at 250 fathoms, and the open sea, as a zoological haunt, stops with the light. It is hardly necessary to say that the pelagic plants are more abundant near the surface, and that below a certain depth the population consists almost exclusively of animals. Not a few of the animals sink and rise in the water periodically; there are some that come near the surface by day, and others that come near the surface by night. Of great interest is the habit of the extremely delicate Ctenophores or “sea-gooseberries,” which the splash of a wave would tear into shreds. Whenever there is any hint of a storm they sink beyond its reach, and the ocean’s surface must have remained flat as a mirror for many hours before they can be lured upwards from the calm of their deep retreat.
Categories: THE OUTLINE OF SCIENCE | 
Tags: Air Water, Carbon Compounds, Chlorophyll, Ctenophores, Dead Plants, Fifty Fathoms, Food Supply, Fundamental Food, Haunt, Microscopic Animals, Nitrates, Open Sea, Plants And Animals, Salts, Sea Bacteria, Sea Gooseberries, Shreds, Surface Waters, Unicellular Plants, Vital Economy | 
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October 27, 2009 | Posted by maneerat
We saw in a previous chapter how the process of evolution led to a mastery of all the haunts of life. But it is necessary to return to these haunts or homes of animals in some detail, so as to understand the peculiar circumstances of each, and to see how in the course of ages of struggle all sorts of self-preserving and race-continuing adaptations or fitnesses have been wrought out and firmly established. Living creatures have spread over all the earth and in the waters under the earth; some of them have conquered the underground world and others the air. It is possible, however, as has been indicated, to distinguish six great haunts of life, each tenanted by a distinctive fauna, namely, the shore of the sea, the open sea, the depths of the sea, the freshwaters, the dry land, and the air. In the deep sea there are no plants at all; in the air the only plants are floating bacteria, though there is a sense in which a tree is very aerial, and the orchid perched on its branches still more so; in the other four haunts there is a flora as well as a fauna—the two working into one another’s hands in interesting and often subtle inter-relations—the subject of a separate study.
Categories: THE OUTLINE OF SCIENCE | Tags: Adaptations To Environment, Air Water, Botanists, Carbon Compounds, Chlorophyll, Deep Sea, Distinctive Fauna, Freshwaters, Narrow Zone, Open Sea, Peculiar Circumstances, Photosynthesis, Pigment, Process Of Evolution, S Rays, Seaweed, Seaweeds, Tide Marks, Underground World, Zoologist | No Comments »
October 22, 2009 | Posted by maneerat
We cannot have more than a speculative picture of the first living creatures upon the earth or, rather, in the waters that covered the earth. A basis for speculation is to be found, however, in the simplest creatures living to-day, such as some of the bacteria and one-celled animalcules, especially those called Protists, which have not taken any very definite step towards becoming either plants or animals. No one can be sure, but there is much to be said for the theory that the first creatures were microscopic globules of living matter, not unlike the simplest bacteria of to-day, but able to live on air, water, and dissolved salts. From such a source may have originated a race of one-celled marine organisms which were able to manufacture chlorophyll, or something like chlorophyll, that is to say, the green pigment which makes it possible for plants to utilise the energy of the sunlight in breaking up carbon dioxide and in building up (photosynthesis) carbon compounds like sugars and starch. These little units were probably encased in a cell-wall of cellulose, but their boxed-in energy expressed itself in the undulatory movement of a lash or flagellum, by means of which they propelled themselves energetically through the water. There are many similar organisms to-day, mostly in water, but some of them—simple one-celled plants—paint the tree-stems and even the paving-stones green in wet weather. According to Prof. A. H. Church there was a long chapter in the history of the earth when the sea that covered everything teemed with these green flagellates—the originators of the Vegetable Kingdom.
Categories: THE OUTLINE OF SCIENCE | Tags: Air Water, Animalcules, Carbon Compounds, Cellulose, Chlorophyll, Definite Step, Flagellum, Globules, History Of The Earth, Lash, Marine Organisms, One Celled Plants, Organic Matter, Paving Stones, Photosynthesis, Protists, Protoplasm, Salts, Vegetable Kingdom, Wet Weather | No Comments »