TYPES OF CCELENTERA — A SEA- ANEMONE. 145 



Fourth Type of Ccelentera. — A Sea-Anemone, such as 

 Tealia crassicornis. Class Scyphozoa. Sub -Class 

 Anthozoa or Actinozoa. 



Most sea-anemones live fixed to the rocks about low- 

 water mark. All these fixed forms have a distinct basal 

 disc, and may, like Tealia crassicornis, be half buried in 

 sand and gravel ; others, without a basal disc, are loosely 

 inserted in the sand, e.g. Edwardsia and Cerianthus, 

 but all are able to shift their positions by short stages. 

 They feed on small animals, — molluscs, crustaceans, 



Fig. 63. — External appearance of Tealia crassicornis. 



worms, which are caught and stung by the tentacles ; 

 but many depend largely on minute organisms, while 

 others may be seen trying to engulf molluscs decidedly too 

 large for them. A few anemones, without pigment or with 

 little, have symbiotic Algre in their endoderm cells ; the 

 bright pigments of many others seem to help in respiration. 

 Besides the sexual reproduction (in which the young are 

 sometimes developed within the parent), some sea-anemones 

 also multiply asexually by detaching portions from near the 

 base, and fission occurs in a few forms. 



External appearance of a fixed Anemone. — The 

 cylindrical body is fixed by a broad base ; it bears whorls 



