30 Dwellers of the Sea and Shore 



are exposed at every low spring tide. So great Is the 

 number of the individual units that they are to be esti- 

 mated only in millions. Excepting, perhaps, the bar- 

 nacles, they are the commonest animals in this region. 



Now, although the mussels are peaceable creatures, 

 their life is not exactly a peaceful one. Living as they 

 do on the organic motes held in suspension in the water 

 and on live food of microscopic dimensions, they have 

 no need of weapons of offense; and as to defense, the 

 two-valved shells w^hich protect their soft bodies are 

 Inadequate to resist the attack of their enemies. And 

 these are many. Few flesh eaters there are that do not 

 take toll of their numbers. Incapable of locomotion — 

 as that term is ordinarily understood — the mussels are 

 easy prey to the starfish, sea urchin, and other slow- 

 moving animals; and these, together with crabs, fishes, 

 and birds, are continually engaged in their slaughter. 



Indeed, it would sometimes appear that the mussels 

 are bent upon destroying each other. They exist In 

 such enormous numbers, layer on layer, that they fre- 

 quently actually poison one another by their waste 

 products. Many, moreover, are smothered by the ac- 

 cumulation of silt and other matter settling down from 

 the upper masses. 



Nevertheless, their worst foe is not themselves. 

 Their deadliest enemy is, however, not far removed in 

 kind. It is, in short, another mollusk. This mollusk Is 

 the moon snail, a creature which is an outstanding 

 example of the amazing contrasts sometimes found in 

 this strange world. 



