. Beginners zoology. Zoology. Fig. 67.— Crinoid, arms closed. The crinoids are the most ancient of the echino* derms. (Figs. 67, 68.) Their fossils are very abundant in the rocks. They inhabited the geological seas, and it is believed that some of the other echinoderms de- scended from them. A few now inhabit the deep seas. Some species are fixed by stems when young, and later break away and become free- swimming, others remain fixed throughout life. The four classes of the branch echinoderms are Starfish {asteroids). Sea urchins (echinoids), Sea cucumbers {holothurians), and Sea lilies (crino
. Beginners zoology. Zoology. Fig. 67.— Crinoid, arms closed. The crinoids are the most ancient of the echino* derms. (Figs. 67, 68.) Their fossils are very abundant in the rocks. They inhabited the geological seas, and it is believed that some of the other echinoderms de- scended from them. A few now inhabit the deep seas. Some species are fixed by stems when young, and later break away and become free- swimming, others remain fixed throughout life. The four classes of the branch echinoderms are Starfish {asteroids). Sea urchins (echinoids), Sea cucumbers {holothurians), and Sea lilies (crinoids). Comparative Review Make a table like this as large as the page of the notebook will allow, and fill in without guessing. Fig. 68. — Disk of Cri- noid from above,show- ing mouth in centre and vent near it, at right (arms removed). Am<Eba Sponge Hydra Coral Polyp Starfish Is body round, two- sided, or irregular What organs of sense Openings into body Hard or supporting parts of body How food is taken How move How breathe '. 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 Coleman, Walter M. Toronto : Macmillan
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectzoology, bookyear1921
