324 THE WONDER OF LIFE 



life. Great- numbers of sedentary animals may live beside 

 one another, like daffodils by the lake side. Large shoals 

 of herring, mackerel and other fishes may swim about 

 together, and it is rather interesting that there are many 

 different names for the various crowds. But association 

 in numbers is not sociality. It will be found difficult, 

 however, to draw a firm hne, for many gregarious animals 

 act together on occasions or may exhibit such devices as 

 posting sentinels. There we see the first hints of societary 

 life. 



Crowds without Sociality. — The fiddler-crabs (species 

 of Gehsimus or Uca) may serve as an illustration 

 of animals hving together in great numbers without there 

 being any real sociahty. They swarm on the mud-flats 

 and estuary-shores near Manila, and in many similar places, 

 — attractive and interesting creatures. One of the great 

 claws of the male is enlarged out of all proportion, and 

 is used as a weapon. According to Colonel Alcock, ' it 

 is used as a signal to charm and allure the female ', but 

 this view is not confirmed by the observations of Mr. 

 A. S. Pearse at Manila. The males certainly dance about 

 the females, but as they keep their backs constantly toward 

 the females the great claw could not be seen. It is not 

 used in burrowing or feeding ; in fact it seems rather in 

 the way, but it is ' of unquestionable use to the male in 

 his combats with his fellows and in defending himself 

 from other enemies '. But our present point is simply 

 that, although the fiddler-crabs hve in great colonies, 

 they show no communal life, except perhaps a certain 

 playfulness. They are fiercely individualistic and very 

 pugnacious. They make burrows and carry away the 

 excavated material ; they close the opening with a plug 



