244 Dwellers of the Sea and Shore 



This is to say, while it is in the water. Out of that 

 medium these features lose their delightful character- 

 istics. And, furthermore, it is on the dry land that the 

 creature spends the greater part of its existence; so, in 

 a sense, the beauty that is the fiddler crab's is attained 

 under unusual, if not unnatural, conditions. 



Now it must by no means be assumed that the crab 

 is a terrestrial animal living in proximity to the sea, 

 that it could live, if need be, on the dry land. The 

 truth is quite the reverse. It can be kept continuously 

 in the water without harm. Nor will it long survive its 

 absence. In a way of speaking, water is to this creature 

 the very breath of life; but it gets all that is necessary 

 for its needs during the short time it is submerged by 

 the tides. Except for this temporary, but very vital, 

 contact, it has slight acquaintance with an aquatic life. 



How does the fiddler crab breathe? How is it that 

 a creature possessing only gills, which we know are 

 strictly water-breathing organs, can with equal facility 

 breathe in the free air? Strictly speaking, it does not 

 breathe the air direct. Its gills lie in two large cavities 

 on the back just under the carapace. These cavities, or 

 chambers, are considerably larger than the gills them- 

 selves and are in reality receptacles for the storage, or 

 retention, of water. When the crab is submerged, an 

 opening to the front of the chamber allows a free cir- 

 culation of water to enter and bathe the gills, which 

 absorb the necessary oxygen to sustain the animal. Out 

 /of the water, however, the opening closes, and the re- 

 tained water absorbs oxygen from the atmosphere, 

 which in turn is transmitted to the gills. 



When the rising tide reaches the level of the 



