122 THE SEA-SHORE 



paper bag, twist up the mouth, and push it 

 downwards, so that the sides of the bag surround 

 it all the way round. You will then have two 

 bags, as it were, one inside the other, the space 

 between the two being filled with air. Now 

 that is just the way in which the body of a sea 

 anemone is formed, with this difference, that 

 the space between the outer bag and the inner 

 one is filled with water. It forms, in fact, a 

 kind of water-jacket. 



Next, remember that all those spreading ten- 

 tacles are really tubes, like the fingers of a glove, 

 closed at the top, but opening at the bottom into 

 this water-jacket. And remember also that the 

 outer walls of the body are formed of very strong 

 muscles. So, you see, when the anemone wants 

 to spread its tentacles, all that it has to do is 

 to contract these muscles. The water is then 

 squeezed up into the tube-like tentacles, which 

 of course expand. When it wants to close them 

 it relaxes the pressure, and the water flows out 

 of the tubes again and back into the water-jacket, 

 so that they all come folding in. 



The lower part of an anemone's body is called 

 the " foot," and is really a big and strong sucker, 

 by means of which the animal clings so firmly 

 to the surface of a rock or a stone that it almost 

 seems to be growing out of it. But these crea- 

 tures do not spend the whole of their lives 



