34 EXPOSED AND CONCEALED ANIMALS 



light and dark bands on the shell constituting 

 a most effective cryptic device. 



The multitudes of floating organisms which 

 compose what is known as the plankton, the 

 primary food - supply of sea, river, and lake, 

 are often rendered invisible by their extreme 

 transparency. The animals which feed upon 

 them do not pursue them by the aid of sight, 

 but simply engulf them. Conversely, many of 

 them have what may be called a phanerotactic 

 mechanism, rendering them phosphorescent and 

 visible at night. The utility of this mechanism 

 to the owners of it is not very clear ; it may 

 be a product of metabolism, neither useful nor 

 dangerous. 



The basic quality underlying all animal life 

 is the cryptic, the fear of the sun. Basking in 

 the sun is a dangerous pastime. 



