64 



The Living Things of the Earth unit i 



Flagellum 



Eye-spot 



Green bodies 



Fig. 92 Eiiglena is another of the protozoa. It 

 lashes itself along with the whip-like hair. Be- 

 cause it covtaijis green bodies soiiie biologists 

 call it a plant. 



it flows along. At one moment the sand 

 is inside the animal, the next moment it 

 is out. 



There is a giant ameba that your 

 teacher may be able to show you. It is 

 called Chaos chaos. It is so large that it 

 can be detected with the naked eye. 



Protozoa swarm in the ocean. One kind 

 of protozoan which floats near the sur- 

 face of the sea builds a complicated shell 

 of lime about its tiny body. Now and 

 again, when there is a sudden change in 

 temperature or in other conditions, these 

 organisms are killed. The millions of 

 shells fall gently to the ocean floor like 

 raindrops in a gentle rain. And so many 

 have fallen throughout the centuries that 

 deep beds of lime shells have been 

 formed. Deposits of these shells can be 

 found at the bottom of the ocean in many 

 places. The chalk cliff's of southern Eng- 

 land and the shores of northern France 



Fig. 93 Skeleton of a Radiolaria?i. These and 

 other protozoan skeletons make up much of the 

 material on the ocean bottom. (American mu- 

 seum OF NATURAL HISTORY) 



are made of limestone rock composed 

 principally of such shells. 



LonCT QCTo seamen noted that there were 

 nights when the ocean sparkled with a 

 thousand lights which seemed to dance 

 on the waves as the vessels plowed along 

 mile after mile. The light is produced by 

 enormous numbers of protozoa called 

 Noctihica (nok-ti-loo'ka). The name 

 means night light. As many as three mil- 

 lion individuals may be found in a quart 

 of sea water when conditions are just 

 right for their growth. See Figures 92 and 

 9:5 for illustrations of other protozoans. 



The animals in review. Many pages 

 back you started a studx' in order to be- 

 come acquainted with the many living 

 things of this earth. In doing this your 

 circle of acquaintances among organisms 

 grew so rapidly that you would have been 

 hopelessly confused had you not learned 

 some system for keeping them in separate 



