THE SCHOOL OF THE SHORE 49 



itself again. One of the hermit crabs (Pagurus 

 cuanensis) in deeper water has its borrowed 

 shell frequently surrounded by a bright orange 

 sponge (Suberites domuncula], with a strong 

 odour, a disagreeable taste, and countless 

 flinty needles which fishes naturally leave 

 alone! 



A LIMB FOR A LIFE 



Many different kinds of animals, especially 

 those with rather lanky limbs, practise a curi- 

 ous kind of surrender a limb for a life. And 

 what they surrender as a ransom for their life 

 they can regrow at leisure. 



This is well illustrated by many star-fishes. 

 If an arm is pinned down by a stone, or seized 

 by an enemy, or if a sea-slug has settled on an 

 arm and cannot be dislodged, the star-fish 

 manages to break off the arm at the base. In 

 so doing it is behaving as we behave when we 

 draw back our finger from a very hot plate, or 

 shut our eye when a stone is about to strike it, 

 or cough when a crumb of bread threatens to 

 " go down the wrong way." We do not think 

 about doing any of these things nor exercise 

 our will ; what we do is called a reflex action, 

 carried out by means of pre-arranged linkages 



