. A textbook in general zoology. Zoology. STAllFISH, SEA URCHIN, BRITTLE STARS 95 to the tips, and it is difficult to tell where the disk stops (Fig. 46). Brittle stars. —These are starfish that are at once dis- tinguished from those above, by the long, slender, tapering, and cylindrical arms. The central disk is also more sharply marked oft' from the arms (Fig. 47). Agam, there are no grooves along the oral surfaces of the arms, antl the tube feet protrude througli the sides of the arms instead of through the ventral walls, and are not provided with suck- ers. Hence, locomotion is effected la
. A textbook in general zoology. Zoology. STAllFISH, SEA URCHIN, BRITTLE STARS 95 to the tips, and it is difficult to tell where the disk stops (Fig. 46). Brittle stars. —These are starfish that are at once dis- tinguished from those above, by the long, slender, tapering, and cylindrical arms. The central disk is also more sharply marked oft' from the arms (Fig. 47). Agam, there are no grooves along the oral surfaces of the arms, antl the tube feet protrude througli the sides of the arms instead of through the ventral walls, and are not provided with suck- ers. Hence, locomotion is effected largely by the slender arms. In some species of brittle stars, the basket stars, the arms are branched many times, producing a complex but beautiful object. Some brittle stars have the remarkable property of being able to throw off pieces of their arms when touched or kri- tated; hence the name, brittle stars. Sea urchins. — Sea urchins are common along the eastern coast of the United States, especially where the shore is rocky. They are globular in shape, but with the side, on which the mouth is situated, flattened. These echinoderms have no distinct arms, l^ut the body is bristling with cylin- drical, pointed spines jointed to the skeleton so that they are movable (Fig. 48). There are also projecting among the spines, five double rows of tube feet radiating from the. Fig. 47. — Brittle starfish. Note that the diili is clearly 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 Herrick, Glenn W. (Glenn Washington), 1870-1965. New York, Cincinnati [etc. ] American Book Company
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1912
