COELENTERATA AND CTENOPHORA 



THE CLASS ANTHOZOA 



The Anthozoa are represented by the sea anemone, Melndium dianlhus, 

 whose solitary individual polyps are common along the New England coast. 

 As in anthozoans generally, the sea anemone is provided with a somewhat 

 flattened oral disk surrounded by tentacles (Fig. 10.13). The epidermis turns 

 in at the mouth and hangs downward into the coelenteron to form a tubular 

 pharynx or stomodaeum. This pharynx is attached to the lateral body wall 

 by a series of radiating partitions or septa, which thus divide the upper part 

 of the coelenteron into radial compartments, continuous with the undivided 

 cavity below. The biradial symmetry characteristic of many Anthozoa is 

 produced by the presence of one or more heavily ciliated grooves or gutters, 

 called siphonoglyphs, traversing the pharynx longitudinally from its outer to 

 its inner edge. These grooves presumably function to provide active currents 

 of fresh, aerated water to the inner parts of the animal, and to flush away 

 wastes. 



Fig. 10.14. A stony coral, Aslrangia danae. E,ach individual occupies a cup-like portion of 

 the calcareous base. In the expanded individual, note the groups of nematocysts on the tentacles, 

 and the edges of the septa in the coelenteron. (Photograph by Bassett Maguire, Jr.) 



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