CCELENTERATA. 



251 



long-lived compared with the Hjdrozoa, living for several 

 years. One kept in an aquarium in England is now more 

 than sixt}' years old. 



1. Soft-bodied Polyps. — The best-known representative 

 of this group is the Actinia {Metridium), or Sea-anemone. 

 It usually leads a solitary life, though frequently several 

 are found together, some of which have arisen as buds from 

 the others. It is capable of a slow locomotion. Muscular 

 fibres run around the body, and others cross these at right 

 angles. The tentacles, which often number over two hun- 

 dred, and the partitions, which are in reality double, are in 

 multiples of six. At night, or when alarmed, the tentacles 

 are drawn in, and the aperture firmly closed, so that the ani- 

 mal looks like a rounded lumpof flesliy substance plastered 

 on the rock. It feeds on crabs and Mollusks. It abounds 

 on every shore, especially of tropical seas. The size varies 

 from one eighth of an inch to a foot in diameter. 



2. Coral Polyps. ^ — The majority of Anthozoa secrete 

 a calcareous or horny framework called "coral." With 

 few exceptions, they are fixed 

 and composite, living in colonies 

 formed by a continuous process 

 of budding. Their structures take 

 a variety of shapes: often dome- 

 like, but often resembling shrub- 

 bery and clusters of leaves. The 

 members of a coral community 

 are organically connected ; eacli 

 feeds himself, yet is not indepen- 

 dent of the rest. We can speak 

 of the individtial Corals, a, i, c, 

 but we must write them down 



abe. The compound mass is "like fio. 200.— Ol■gan-pipeCo^al(^«M■ 

 , . , , I, , , , pora muaiea). ludiau Ocean. 



a living sheet or animal matter, 



fed and nourished by numerous mouths and as many 



stomachs." Life and death go on together, the ,old 



