Sometimes one corallite is inhabited by a single pair of crabs of one 

 species, which is achieved by intraspecies agonistic behavior (Preston, 

 1973). Twelve species of fish of the genus Amphiprion are obligate 

 symbionts, exhibiting territorial behavior (protection of "their" sea 

 anemone as long as they are located near it). If the anemone is removed, the 

 territorial behavior decreases, and the feeding and aggressive forms of 

 behavior are altered. The closeness of direct and indirect topic and 

 phoric interdependence can be quite varied; for example, in the various 

 species of Amphiprion or among shrimp from the families Hyppolytidae , 

 Alpheidae and Palaemonidae , associated with a broad range of benthic 

 invertebrates and even pelagic scyphomedusan (Bruce, 1972; Fankboner, 197?). 



In representatives of the mobile epifauna, the primitive form of 

 collective reactions is rather passive. Thus, the brittle stars Astroboa 

 nuda form unusually close settlements in the shallow waters of coral reefs. 

 The arms of the individuals intertwine, forming a dense net across the 

 direction of the current. This "plankton net" assures effective, nonselec- 

 tive filtration of the bottom-dwelling copepod (Tsurnamal , Harder, 1966). 

 It has been shown that each star occupies the same position each night, and 

 retreats to the same shelter each day (Fricke, 1973). Similar behavior is 

 exhibited by Ophiothrix g racil is . 



Any systematic encounter of individuals, resulting in a change in the 

 course of individual motor reactions or combinations of motor reactions, 

 must be considered an evolutionarily more advanced form of group ("social") 

 behavior. Strictly speaking, nongroup, purely individual, behavior, in the 

 precise sense of this word, cannot be achieved in nature, since some 

 minimal interaction between individuals always occurs, at least in some 

 stage of ontogenesis. However, obligatory group behavior is the most fully 

 integrated form of living activity, though its population adaptiveness is 

 not always obvious. This category of nontrophic connections must include 

 all aspects of intra- and interspecific domination-subordination relation- 

 ships (Wynne-Edwards, 1962), since they also regulate the size of populations 

 and increase qualitative variety of genotypes due to complete or partial 

 elimination of a number of "unsuitable" individuals from the breeding pool. 

 Thus, after establishment of a hierarchy in a group of Diogenes p ugilator 

 hermit crabs, the dominant male eats more food and moults more frequently 

 than the subordinate males (Rossi, 1971). In the D ardanus a rrosor hermit crabs, 

 living in symbiosis with the Calliactis parasitica sea anemone, the anemone 

 is always captured by the dominant crab, regardless of whether it already 

 has a symbiont on its shell or not. The subordinate crab does not take 

 an anemone in the presence of the dominant crab, even if the shell of the 

 dominant crab is already occupied by anemones, so that a free anemone has 

 fallen to the bottom (Mainardi, Rossi, 1969). In the squid Lol igo 

 pealei , a hierarchical structure of behavior of the males during breeding is 

 observed. When there are more males than females, the subordinate males 

 are not allowed to mate. The hierarchical behavior is not manifested 

 during feeding (Arnold, 1962). 



Competition between an individual and a group is frequently replaced 

 by ritualized behavioral elements, a sort of "psychic attack" (Severtsov, 



28 



