Beginners' zoology . Fig. 60.—Young starfish crawling upontheir mother. (Challenger Reports.) ECHINODERMS (^SPINY ANIMALS) 39 feet arranged? Where do the rows begin and end? Would youthink that a sea urchin placed upside down in water, could right it-self less or more readily than astar-fish? What advantage inturning would each have that theOther would not have? Thename sea urchin has no refer-ence to a mischievous boy, butmeans sea hedgehog (Frenchoiirsm, hedgehog), the namebeing suggested by its spines. Comparison of Starfish andSea Urchin. — The water sys-tem of the sea urchin, consist-ing
Beginners' zoology . Fig. 60.—Young starfish crawling upontheir mother. (Challenger Reports.) ECHINODERMS (^SPINY ANIMALS) 39 feet arranged? Where do the rows begin and end? Would youthink that a sea urchin placed upside down in water, could right it-self less or more readily than astar-fish? What advantage inturning would each have that theOther would not have? Thename sea urchin has no refer-ence to a mischievous boy, butmeans sea hedgehog (Frenchoiirsm, hedgehog), the namebeing suggested by its spines. Comparison of Starfish andSea Urchin. — The water sys-tem of the sea urchin, consist-ing of madreporite, tubes, andwater bulbs, or ampullae, issimilar to that of the tube feet and locomotion are alike. There is no need forwell-developed respiratory organs in either animal, as the wholebody, inside and out, is bathed in water. The method of repro-duction is the same. The starfish eats soft animal food. The food of the seaurchin is mainly vegetable, and it needs teeth (Fig. 62, 63 ) ;. Fig. 61. — A Sea Urchin crawling upthe glass front wall of an aquarium(showing mouth spines and tube feet).
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectzoology, bookyear1921
