102 THE HAUNTS OF LIFE 



zoese, marked by a spine rising vertically above 

 the back, and by a tail sticking out at an 

 angle to the rest of the body. These larvae are 

 swept out into the safety of the open water, and 

 they swim about near the surface. They feed, 

 they grow, they moult, and another form of 

 larva results. This does the same, and a 

 Megalops larva results, which is beginning to 

 be like a crab. It has lost the spine; it has 

 stalked eyes; it has got its full complement 

 of legs. Now this Megalops bends its tail 

 forwards and upwards underneath the anterior 

 part of the body (the cephalothorax] ; it 

 ceases to be a free-swimmer ; it sinks to the 

 floor of the sea, and creeps up the slope 

 to its birthplace on the shore a little crab 

 about half the size of the nail of our little 

 finger. 



There is an interesting illustration of " The 

 Balance of Nature " in this connection. It 

 seems that the shore-waters are, on the average, 

 richer in Plankton than any other waters, the 

 reason being that they are always receiving 

 abundant supplies of valuable salts brought 

 down from inland by rivers and streams. So 

 the shore-waters serve as a sort of nursery of 

 minute creatures that get swept out to sea to 



