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TEXTBOOK OF ZOOLOGY 



These protrude through pores (cinclides) in the body wall to the 

 outside, and they are supplied with nematocysts and secretory cells. 

 They serve as defensive as well as offensive structures. 



Asexual reproduction by budding from the margin of the basal 

 disc is practiced by this animal. Occasional longitudinal fission may 

 occur. The gonads develop on the edges of the lower part of the 

 septa to provide for sexual reproduction. The sexes are distinct. 



Cinclade, with 

 Aconlium protruding 



SlereogTam of Anthozoan Polyp 



MeKtilcrie fiUment, 



Hollcw 

 Tentacle 



Vf)i.tfsl ^' 



Siphonogtyph 



SpSincler 



Diagrammatic T. S. of Anthozoan Polyp fi\ level A-A 



EnJoceet, cKamter between 



two metenteriei of , 



the ume pair "-^^ 



Cxaeoel. cKsmber 

 between pair* ^ 

 o( meicnteriei ' ■^ 



Directive* 

 (Ventral bet of 

 Primary Meccnteriea) 



Otagrammatic T S. of Anthozoan Polyp at level B-B 



Fig. 66. — Diagrams to show the structure of the anthozoan, Metridium, (Courtesy 



of Pacific Biological Laboratories.) 



Mature ova and spermia are discharged into tlie water of tlie cavity 

 and escape through the mouth to unite in fertilization outside. The 

 development includes cleavage and planula stages, before the new 

 individual attaches and changes form. 



Order Madreporaria. — The representatives of this order secrete an 

 external limestone skeleton ; most of them are colonial. The indi- 

 viduals of colonies communicate with each other by coenosarcal con- 

 nections. Otherwise they are similar to anemones. Astrangia, Madre- 

 pora, and Oculina are examples. 



