vertebrates

Question
Do rats have vertebrates or skeletal systems?  Can they flatten themselves to manuever under door?

Answer
Yes; rats have vertebraes and a skeletal system.. they're bone, muscle, tendon and ligaments just like us humans. As a general rule of thumb, if a rat can squeeze their head through, they can fit into just about anything. They have a very flexible skeleton that allows them to creep pretty much anywhere.

http://visual.merriam-webster.com/images/animal-kingdom/rodents-lagomorphs/roden...

There's a breakdown, for reference.