CHAPTER IX 



FRESHWATER MUSSELS 



THE freshwater mussels are the largest of all the molluscs that 

 occur in this country. They are exceedingly common, being 

 found in nearly all ponds, canals and streams ; but frequently 

 escape notice owing to their habit of burying themselves in the 

 mud and dead leaves at the bottom. The broken shells brought 

 to the bank by various water-fowl which devour them will usually 

 betray the presence of others in any given piece of water. The 

 living animals can be scooped up in a strong landing net, or often 

 obtained by hand if the water is sufficiently shallow to permit 

 wading. A little practice will enable any one to detect the gaping 

 valves and short siphons of the mussels as they project from 

 the mud ; and if a finely pointed stick be thrust between the 

 valves, the animals will close the shell so firmly upon it that they 

 can be pulled up and safely landed without wading or using a 

 net. In captivity the mussel should be kept in shallow vessels 

 in order that the whole mass of water may be well aerated. It is 

 not necessary to provide mud in which they can burrow, for 

 they will live many weeks lying on their sides in clean water 

 contained in earthenware vessels ; but care should be taken to 

 prevent the temperature of the water becoming high. It is best 

 to place the vessels in permanent shade. If, however, the natural 

 conditions are desired, the mussels must be put in a glass-sided 

 aquarium at the bottom of which a layer of river sand, 3 

 or 4 inches deep, has been placed. The water should be not 

 more than 6 inches deep, and should contain a fair supply of 

 water-weeds to maintain the supplies of oxygen. It is then 

 possible to watch the animals move about, bury themselves in 

 the sand, and, if a few sticklebacks are also placed in the same 

 aquarium, to see some of the early stages of the life-history. 



Four species of freshwater mussel occur in the British Isles ; 



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