41. What is green scum? 



The green scum on ponds and slow-flowing rivers is formed by float- 

 ing green and blue-green algae and a tiny flowering plant called duck 

 weed. The duck weed and floating green algae do not live in sea water, 

 but the blue-green algae do. These blue-green algae have a sticky cover- 

 ing and form slimy films on rocks and pilings. Mermaid's Hair, a large 

 blue-green alga, forms thick feathery coverings on rocks and boat 

 bottoms. 



Algae are classified not by color but by structural relationship to 

 other species of algae; it is "blue-green" algae that make the Red Sea 

 red. Some "red" algae are either pink or white, and there is one "red" 

 alga in the upper intertidal zone that is olive-green. 



Dawson, E. Yale 



Marine Botany, Holt, Rinehart and Winston, Inc., 1966. 

 Miller, Robert C. 



The Sea, Random House, 1966. 

 Odum, Eugene P. 



Fundamentals of Ecology, W. B. Saunders Company, 1959. 



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