178 The Under-Water World 



Sciaenoids the air-bladder is developed 

 to an extraordinary extent, and with the 

 movement of the gases inside from one 

 compartment to another, it is thought 

 that the wall of the bladder is set in 

 motion. The muscles surrounding the 

 compartments may contribute to the 

 vibration by rapidly extending and con- 

 tracting." 



In a previous chapter mention has been 

 made of certain young fish that live 

 under the protection of a jellyfish. Still 

 more remarkable is the case of the golden 

 and light blue coral fish of the Dutch 

 East Indies, Amphiprion percula, which 

 spends the greater part of its life within 

 the body cavity of an anemone. The 

 anemone receives compensation for the 

 shelter that it affords by receiving a food 

 supply from the fish, living upon the 

 waste matter that is ejected by its 

 paying guest. These fish are frequent 

 boarders at the Zoo Aquarium, but, unlike 



