. Beginners' Zoology . long,streamer-like tentacles of the jellyfish. These, like thetentacles of the hydra, havenettling cells (Fig. 41). The umbrella-shaped freeswimming jellyfish is called amedusa (Fig. 44). Coral Polyps. — Some of thesalt water relatives of the hydraproduce buds which remainattached to the parent without,however, becoming differentfrom the parent in any coral polyps and corallines are examples of colonics ofthis kind, possessing a common stalk which is formed asthe process of multiplication goes on. In the case of coralpolyps, the separate animals and the flesh con
. Beginners' Zoology . long,streamer-like tentacles of the jellyfish. These, like thetentacles of the hydra, havenettling cells (Fig. 41). The umbrella-shaped freeswimming jellyfish is called amedusa (Fig. 44). Coral Polyps. — Some of thesalt water relatives of the hydraproduce buds which remainattached to the parent without,however, becoming differentfrom the parent in any coral polyps and corallines are examples of colonics ofthis kind, possessing a common stalk which is formed asthe process of multiplication goes on. In the case of coralpolyps, the separate animals and the flesh connecting themsecrete within themselves a hard, li^ny, supportitig structureknoivn as coral. In some species, the coral, or stony part,is so developed that the polyp seems to be inserted in thecoral, into which it withdraws itself for partial protection(Fig. 45). The corallifies secrete a smooth stalk which affordsno protection, but they also secrete a coating or sheathwhich incloses both themselves and the stalk. The. Fig. 45. —CoKAL Polyps (tenta-cles, a multiple of six). Noticehypostome. r 32 BEGINNERS ZOOLOGY coating has apertures through which the polyps prp-trude in order to feed when no danger is near (Fig. 46).
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