Subject: How can you tell if a earthworm is alive??

For my Science fair project I decided to do it on the study of cryobiology.  I 
first wanted to try to freeze something and bring it back to life and then I 
realized that it could not be done.  So I want to see how earthworms react to 
the freezing cold.  And I was going to put the earthworm in a cup and some dirt 
and then put it in my freezer and see how it reacted at different freezing 
temperatures.  But how can I tell if it is dead?? I can't exactly take its 
pulse.
Thank You

Re: How can you tell if a earthworm is alive??