70 THE SEA-SHORE 



nearly always has a number of tufts of sea-weed 

 or sponge growing upon its back. 



Perhaps you might think that these come 

 there by accident. But they do not. The crab 

 himself plants them there ! If you keep him in 

 an aquarium you may often see him doing so. 

 First of all he turns one of his long claws over 

 his back and scratches away at the carapace, 

 so as to roughen the surface. Then he pulls up 

 a little sprig of sea-weed or sponge and actually 

 plants it on his shell, pressing the rootlets firmly 

 down. And besides the spikes upon the shell 

 there are numbers of tiny hooks, which help to 

 hold it in position. Then the crab plants another 

 piece of weed or sponge in just the same way, 

 and so he goes on planting piece after piece 

 until his back is completely covered. 



Now why do you think he takes all this trouble ? 



Well, the reason is that he does not want to 

 be seen; for he has a great many enemies, and 

 he knows perfectly well that if he were to lie 

 among the sea-weeds or sponges at the bottom 

 of the sea they would be quite sure to notice 

 him as they passed by, and then he would almost 

 certainly be killed and eaten. So he clothes 

 himself with either sea-weeds or sponges, as the 

 case may be, and then feels that he is perfectly 

 safe, and that as long as he keeps quite still even 

 the sharpest eye will fail to notice him. And if 

 you catch one of these crabs which is covered with 



