522 



Phylum Mollusca 



■ 1918. Self-fertilization in the air-breathing pond snails. Biol. Bull. 35:48. 



Crabb, E. D. 1927. The fertilization process in the snail Lymnaea stagnalis ap- 



pressa Say. Ibid. 53:67. 

 Walter, Herbert E. 1906. Behavior of the pond snail Lymnaea elodes. Cold 



Spring Harbor Monographs No. 4. 



REARING AQUATIC PULMONATE SNAILS 



Elmer Philip Cheatum, Southern Methodist University 



IN THE artificial rearing of snails one cannot ignore the natural en- 

 vironmental conditions to which each species is best adapted. Much 

 better results are secured in the culture of snails if field conditions are 

 simulated as nearly as possible in the laboratory aquaria. 



In the rearing of hundreds of lake, pond, and marsh-inhabiting snails 

 the author early discovered that conditions favorable for the growth of 

 one species may be rather adverse for another. For example, the depth 

 of water in rearing aquaria proves to be an important factor. The 

 large marsh-inhabiting species such as Lymnaea megasoma, L. palustris, 

 Helisoma trivolvis, and the smaller lymnaeids and physids thrive better 

 in aquaria containing 2 or 3 inches of water than in aquaria containing 

 10 or 12 inches of water. Species inhabiting the more open bodies of 

 water in a lake such as Physa parkeri, Lymnaea emarginata angulata, 

 L. stagnalis, Helisoma campanulatum, and H . antrosum live equally well 

 in either deep or shallow water. It is generally much better, then, 

 to rear snails in aquaria with glass sides (for photosynthetic purposes) 

 that are wide and shallow rather than narrow and deep. 



A layer of sand and gravel about 1 inch in thickness should be placed 

 on the bottom of each aquarium. This serves as support for the roots 

 of aquatic plants which are grown as a source of food supply as well 

 as for oxygenation of the water. After planting the vegetation in the 

 aquarium it is best, if at all feasible, to use the same water in the 

 aquarium as that from which the snails came. If it is not convenient to 

 do this, usually it is much better to use water from some nearby pond or 

 stream rather than to use tap water which may contain harmful sub- 

 stances. 



Food is a very important item in snail culture. Filamentous algae 

 and Elodea are excellent aquarium plants, since both are active photo- 

 synthetically and are fed on by snails. Thin slices of apple, lettuce 

 leaves, small sticks, and dead leaves covered with microscopic plant 

 life should frequently be placed in the aquaria. If the water in the 

 aquarium is several inches deep the sticks should be so arranged that 

 snails may use them as highways in reaching the surface for air. It is 

 wise to remove such objects as leaves and twigs at least once each week 

 and replace them with fresh material preferably collected from the same 

 pond or stream from which the snails were secured. 



