156 



THE RISE OF ANIMAL LIFE 



Fig. 8-19. A giant sea anemone (Condy/ocf/s gigonfea) found near Bermuda. The tentacles are highly colored. 



and Pacific Coasts, extending from Alaska 

 and Maine to Southern California and 

 Florida, abound with anthozoans (Figs. 

 8-17, 18, 19, 20). Some are found in the 

 polar regions, some at great depths, but 

 they are most numerous in shallow waters 

 in the warmer seas. 



The sea anemone usually remains in one 

 place for a long period of time; some have 

 been observed to live for years in a small 

 depression in rock just below low tide level. 

 It can move slowly on its pedal disc and 

 some of the smaller ones are able to swim 

 by beating their tentacles. It feeds on any 

 unsuspecting crustacean, mollusk, or even 

 fish that comes within reach of its tentacles. 

 Once the prey is paralyzed by the nemato- 

 cysts it is taken into the coelenteron, and di- 

 gestion goes on much the same as in other 

 coelenterates. The sea anemone, in spite of 

 its tough outer covering, is preyed upon 

 by a variety of animals such as fish, starfish, 

 and Crustacea. When in danger it can re- 



tract its tentacles, fold them inside the 

 body, and contract its entire body until it 

 is nearly flat against the substratum. In this 

 condition it is very difficult to remove, in 

 fact, the body is often torn apart before its 

 grasp is released. Although it usually re- 

 produces sexually, occasionally an anemone 

 is found undergoing fission, either longi- 

 tudinally or transversely. 



Other interesting anthozoans, resem- 

 bling the sea anemones in many respects, 

 are the corals ( Fig. 8-20 ) . These are usually 

 very small and live in stony cups, of specific 

 design, made by the limy secretions from 

 the base. The colonies lie in close proximity 

 and after thousands of generations, produce 

 the massive corals, bits of which are fre- 

 quently seen reposing as mantelpiece orna- 

 ments in many homes. Corals live in vvami 

 waters for the most part, although there is 

 one species, Astrangia, living as far north 

 as Maine. They abound in many tropical 

 seas of the world, particularly in the Coral 



