4 THE ROLE OF ALGAE AND PLANKTON IN MEDICINE 



"Plankton," directly from the Greek, is defined by Webster 31 as "the 

 passively floating or weakly swimming animal and plant life of a body of 

 water-." The term appears to have been first used by Hensen in Germany 

 about 1889, although Johannes Mueller collected microscopic organisms 

 as early as 1845 by dragging a very fine net through the sea. 80 



As used today, the term "plankton" generally encompasses the count- 

 less billions of minute animals and plants (excepting bacteria) which 

 reside in water. This includes the algal growths seen floating in fresh 

 water ponds or lakes, and also the minute organisms in the sea. The latter 

 provide, directly or indirectly, the basic food for all forms of aquatic 

 life, from the smallest polyps to the largest whales, with each devouring 

 some form smaller or weaker than itself. Whipple 42 describes it thus: 

 "Fish feed upon Crustacea and insect larvae, the Crustacea prey upon the 

 rotifera and the protozoa, the rotifera and protozoa consume algae and 

 bacteria, and finally algae nourish themselves by the absorption of soluble 

 substances and gases provided in part by the decomposition of animal 

 and vegetable matter brought about by bacteria." This biological sequence 

 is perhaps more graphically characterized in the old Chinese proverb 43 : 



Big fish eat little fish 

 Little fish eat shrimp 

 Shrimp eat mud. 



And the "mud" comprises the multitudinous microscopic organisms 

 at the base of this amazing nutritional pyramid! 



It is apparent, then, that plankton exists in two basic forms, zoo- 

 plankton (animal) and phytoplankton (plant) 44 : 



1. Zooplankton, consisting of shrimplike crustaceans; floating fish 



eggs and larvae; and larvae of crabs, molluscs, and a num- 

 ber of other small animals. Most important, in volume and 

 edibility, are the copepods and krills. 



2. Phytoplankton, consisting almost exclusively of microscopic algae. 



Main types are the diatoms and unicellular flagellates. 



The term "ultraplankton" refers generally to the most minute forms 

 (nannoplankton) of marine plankton, as differentiated from the bulk of 

 phytoplanktonic organisms too large to be eaten by young larvae. Cole 45 

 suggests substituting the term "hekistoplankton" for greater accuracy; he 



