CHAPTER XVII 



BRANCH OELENTERATA: THE POLYPS, SEA- 

 ANEMONES, CORALS, AND- JELLYFISHES 



The structure and life-history of an example of the 

 polyps (the Fresh-water Hydra, Hydra sp.) has been 

 studied in Chapters X and XI. 



OTHER POLYPS, SEA- ANEMONES, CORALS, AND 

 JELLYFISHES 



TECHNICAL NOTE. The teacher should have, if possible, several 

 pieces of coral and a few specimens of Coelenterates in alcohol or 

 formalin, which will show the external character, at least, of these 

 animals (see account of laboratory equipment, p. 450). If the 

 school is on the coast, the pupils should be shown the sea-anemones 

 of the tide-pools. 



The animals which are included in the branch Ccelen- 

 terata are, at least in living condition, unfamiliar to most 

 of us. Like the sponges, they are almost all inhabitants, 

 of the ocean; a few, like Hydra, live in fresh water. 

 Like the sponges, too, most of the members of this 

 branch are fixed, and in their general appearance suggest 

 a plant rather than an animal. The name zoophytes, or 

 plant-animals, which is often applied to these animals is 

 based on this superficial resemblance. But many of the 

 Coelenterates lead an active free-swimming life. This is 

 true of the jellyfishes which float or swim about on or near 

 the surface of the ocea^P Many of the zoophytes spend 

 part of their life in an active free-swimming condition 



before settling down, becoming attached and thereafter 



92 



