Recently in the lab prep room at school,  I was observing a swampy tank that
had a large population of Helisoma duryi   (ramshorn freshwater snails)  in
it. They are probably in their 4th generation.  My question pertains to their
behavior.  I have noticed that about 85% of the animals are found floating up
and down. They move in verticle motion starting from the bottom and moving on
up.  When they reach the top  they stop, and begin sinking slowly to the
bottom.  The animal is fully extended and  there is no visible radula motion.
There is an abundance of Elodea that has begun the decomposing process. ( this
tank wasn't set up to be an actual tank  we all have just been too lazy  to
clean it up) I am very intruiged by this behavior.   I have kept  various
snails  in tanks for the past 3 years ( my mother loved that hehehehe)  and I
have never  seen this before.   My boss ( the lab tech)  was asking me  what
were the snails doing  and I couldn't give her an answer.  Does anyone have
any idea  what this behavior is.  Thank you.
   Sincerely Sarah Watson____@v