They're rod puppets. From what I understand the originals were extremely basic, just basically rats on sticks that could be wiggled around. Over the years they were rebuilt with more and more sophisticated mechanisms.
This is a good example of a rod puppet mechanism:
The design is different, but the basic principles and mechanics are the same.
A really good book to read about this subject is "
Hand and Rod Puppets" by Hansjurgen Fettig. It is out of print, but you can sometimes find copies at the library through inter-library loan.
You can find some designs for rod puppets on my
Puppet Building Resources Pinterest Page too.