. Animal forms; a second book of zoology. Zoology. THE CCELENTERATES colony is fitted for a free-swimming existence. What cor- responds ordinarily to the attached stalk in other forms terminates in a bladder-like expansion, distended with gas, that serves as a float. From it are suspended individ- uals resembling great stream- ers sometimes many feet in length, without mouths, but loaded with nettle-cells that enable them to capture the food, which is conveyed to the second type, the nutritive polyps. Each of these is a simple tube bearing a mouth, and within them the food is digested and dist
. Animal forms; a second book of zoology. Zoology. THE CCELENTERATES colony is fitted for a free-swimming existence. What cor- responds ordinarily to the attached stalk in other forms terminates in a bladder-like expansion, distended with gas, that serves as a float. From it are suspended individ- uals resembling great stream- ers sometimes many feet in length, without mouths, but loaded with nettle-cells that enable them to capture the food, which is conveyed to the second type, the nutritive polyps. Each of these is a simple tube bearing a mouth, and within them the food is digested and distributed by means of a branching gastric cavity extending throughout the entire colony. Then there are individuals like mouthless jelly-fishes which bear the eggs and care for the perpet- uation of the colony; and be- sides these there may be some whose duty it is to defend the rest, and others whose active swimming movements, to- gether with the wind, drive the colony about. Thus uni- ted, sharing the food supply and working for the general welfare of all, the members of this colony live in greater security and with less effort than if, as separate individuals, each was fighting the battles of life alone. 38. Scyphozoa.—The greater number of the larger and more conspicuous jelly-fishes are included under this term. In general shape and locomotion they resemble those of the. Fig. 20. A colonial jelly-fi^h {Physalia). From Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Jordan, David Starr, 1851-1931; Heath, Harold, 1868- [from old catalog] joint author. New York, D. Appleton and company
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectzoology, bookyear1902
