thing you can imagine, and incidentally, if you take the Thalassia 

 leaves and strip them off you will find a symbiotic effect here 

 with one species of diatom of which we have not determined the 

 name. This one species of diatom lives in crevices on the sur- 

 face of the Thalassia . When you strip off the outer membrane 

 and look at it under a phase microscope you will see that almost 

 the entire surface is covered with this diatom. It is hard to 

 know what special relationships you have here. Are the diatoms 

 between the bacteria and the water, or bacteria between the dia- 

 toms and the water, and which is feeding on which? It is a tre- 

 mendous problem in ecology in which I think we should have more 

 interest. 



Davis; 



We found 20 different species of algae on Thalassia. Sometimes 

 six of them on top of each other. One of my students found 20 

 piled on top of each other. 



Burkholder: Is this a food chain or just mechanical? 



Davis: It is mechanical - epiphytic. All these underwater plants have 



algae all over them. The plankton is nothing more than what is 

 swept off of them. The number of species in Florida springs 

 is sometimes between 20 and 30 epiphytic on one plant. 



Pomeroy: 



When you mention the production of the Thalassia beds of course 



you are lumping in a production of aufwuchs, 

 is a significant part? 



Do you think that 



Burkholder: 



Oh, it is a very large part of the total production of the Thalassia 

 beds. There are so many green things there. 



Vallentyne: I take it, from what you have said, that perhaps there has been 

 something done recently on the role of vitamins in this relation- 

 ship between the zooxanthellae and corals. Is that so? 



Burkholder: 



Vallentyne: 

 Burkholder: 



Vitamins are put into the solution in which zooxanthellae are 

 cultivated in the laboratory now. They have to be put in appar- 

 ently. I do not know where they come from in nature. 



Do the corals themselves produce it (B,-,)? 



I would not think so. I think they pick it up from bacteria in the 

 water. We have made quite a study of the origin of vitamin B22 

 in water and it comes from two places: bacteria in the mud and 

 the actinomycetes and bacteria in the water. I don't know of any 

 animal that produces Bj2» ^^ 7°^ want to call coral an animal. 

 The animal part of the coral complex I should think would not be 

 expected to make B]^2> ^o the bacteria must be filtered out by 

 the polyps. Perhaps this complex situation gets the vitamins 



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