THE BIOME AS A SOCIAL ORGANISM 25 



munities. However, further consideration discloses that this is not 

 the case, because of the fact that land plants in their community 

 relations have given expression to many of the chief features of com- 

 munity dynamics. This is an outcome of the rule that plants are 

 practically the universal dominants on land and in shallow fresh water, 

 and it derives also from the unity of the biome arising out of the 

 coactions of plants and animals. The fact that the role of animals in 

 both reaction and coaction was either ignored or not definitely evalu- 

 ated merely requires modifying the list of causes involved and the 

 interpretation of community units with reference to one another. As 

 shown in the succeeding chapter, nearly all the reactions on soil, with 

 the occasional exception of those of earthworms and a few rodents, 

 have been ascribed to plants, and the important effects exerted by 

 animals have been mostly overlooked. In general, the field of animal 

 influence in the biotic community from this viewpoint has hardly been 

 touched. 



When the ocean is taken into purview, it is seen to exhibit nearly 

 every type of dominance to be found on land and in fresh water, and 

 possibly other types still. For example, Zostera and Phyllospadix 

 are submerged dominants essentially identical with their relatives in 

 fresh water, while Ruppia maritvma actually occurs in both coastal 

 bays and saline ponds in the interior. The tropical and subtropical 

 corals assume forms often very like those of plants; they may provide 

 resting and hiding places, shelter and food for other animals, much 

 after the manner of grasses and shrubs on land (Brooks, 1893:30). 

 Corals furnish shade, retard circulation, and modify gases and solutes, 

 reactions more or less parallel to those upon light, wind, and air in 

 forest and thicket. In terms of accumulated material, their reaction 

 may surpass that of land or fresh-water plants (Bourne, 1910) , since 

 borings reveal coral rock hundreds of feet in thickness in some islands 

 of the Pacific. The coralline algae, though much smaller, play a 

 similar part in warm seas, forming deposits often of great thickness, 

 as Howe has recently shown (1932). 



The food coactions in the ocean differ greatly from those on land, 

 and to a large degree from those in fresh water. The overwhelming 

 number of producent organisms belong to the phytoplankton; the 

 consuments run the entire gamut of animal classes from protozoans 

 to mammals. The food relations are further peculiar in that there is 

 a wide transport of plankton organisms, both living and dead, as well 

 as of organic detritus, and a considerable amount of organic mate- 

 rial in solution, which may enter into the food cycle. 



