. Elementary textbook of economic zoology and entomology. Zoology; Insect pests. 92 ECONOMIC ZOOLOGY AND ENTOMOLOGY fluid, the perivisceral fluid, which bathes all of the tissues and fills the body-cavity. The perivisceral fluid is aerated through the respiratory caeca which, as we have seen, are outpocketings of the thin body- wall which extend outward between the calcareous plates of the body. Surrounding the stone canal is a thin membranous tube, and within and by the side of the stone canal is a soft tubular sac. The functions of these organs are not certainly known. calcareous spine respi
. Elementary textbook of economic zoology and entomology. Zoology; Insect pests. 92 ECONOMIC ZOOLOGY AND ENTOMOLOGY fluid, the perivisceral fluid, which bathes all of the tissues and fills the body-cavity. The perivisceral fluid is aerated through the respiratory caeca which, as we have seen, are outpocketings of the thin body- wall which extend outward between the calcareous plates of the body. Surrounding the stone canal is a thin membranous tube, and within and by the side of the stone canal is a soft tubular sac. The functions of these organs are not certainly known. calcareous spine respiratory caeca. —ossicles — ampulla 'tube fool epithelium of (he body cavity y$ ""•^r—L§?ft mesentery— pyloric caecumr ambulacral ossicle- ectodermal covering— pedicellaria—^H/w ,/ .radial'canal radial blood-vessel FIG. 32.—Semi-diagrammatic figure of cross-section of the ray of a starfish, Astcrias sp. The nervous system consists of a nerve-ring about the mouth, and nerves running from this ring beneath the radial canals along each arm. The starfish feed upon other marine animals, especially on molluscs. They are often very destructive on oyster beds, where they may occur in such numbers as wholly to deplete the beds unless they are removed by means of rakes or tangles of ropes that are dragged over the beds for this purpose. When the starfish wishes to feed on a mollusc that is too. 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 Kellogg, Vernon L. (Vernon Lyman), 1867-1937; Doane, Rennie Wilbur, 1871-. New York, H. Holt and company
Size: 1638px × 1526px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookaut, bookpublishernewyorkhholtandcompany, booksubjectzoology
