Attack of the Crab Monsters(1957)

A group of scientists is sent to investigate why another group of scientists researching nuclear radiation has disappeared! 

They soon discover that the reason for the previous group disappearing was huge mutated crabs, which absorb your intelligence after they eat you!  They also communicate with their victims through metal objects.

After just about everyone is eaten, Russell Johnson sacrifices himself by toppling a radio antenna on the last crab and electrocuting it!