106 
Aquatic Lite 
Right-handed Left-handed 
Lea 
rit 
Saiz) 
con 
JER 
show the various parts of the shell of an 
operculate snail. Snails, like men, have 
mouth, eyes, gullet, stomach, intestines, 
heart, one or more kidneys, sometimes a 
iung, one or more sexual organs, a foot, 
a muscular system, a nervous system and 
a sense of touch. ‘Their senses, in some 
cases, are not acute. For instance, a 
ARN 
« w\ 
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Lig dea 
Planorbis 
Aperture / 
Parietal wall Pleurocera 
Operculum elevarum 
Four-tlorned Snail 
(Ampullaria gigas) 
snail is not keen sighted. At least, like 
the fish, he is near-sighted. On the other 
hand, his sense of touch is good. The 
writer has found that the slightest touch 
will cause the four-horned snail to drop 
instantly to the bottom, and close his 
operculum. The sense of smell must also 
be good, for every aquarian knows the 
