CCELENTERATA. 251 



long-lived compared with the Hydrozoa, living for several 

 years. One kept in aquaria in England is now more than 

 sixty } T ears old. 



1. Soft-bodied Polyps. The best-known representa- 

 tive of this group is the Actinia, or Sea -anemone. It 

 leads a single life, and 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 hundred, 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 animal looks like a rounded lump of fleshy 

 substance plastered on the rock. It feeds on Crabs and 

 Mollusks. It abounds on every shore, especially of trop- 

 ical 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 imitating shrub- 

 bery and clusters of leaves. The 

 members of a coral community 

 are organically connected ; each 

 feeds himself, yet is not indepen- 

 dent of the rest. We can speak 

 of the individual Corals, a, S, c, 

 but we must write them down 

 abc. The compound mass is "like FIG. 200. organ-pipe c 



i . . , . . , pora musica). Indian Ocean. 



a living sheet of animal matter, 



fed and nourished by numerous mouths and as many 



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



