How do insects move without muscles?

Question

I understand that most animals use muscles to move. (ie. biceps to bend elbow, triceps to straighten elbow), but how do insects move when they don't have muscles?

Answer 1

The muscles are there, but their skeleton is located on the outside of their bodies, referred to as an "exoskeleton". Which works out great for them as it provides a natural armor to protect them from predators.

Answer 2

They do have muscles.  They are just attached to the exoskeleton.

Answer 3

they do have muscles

but i know that spiders (so maybe insects too) walk by pumping blood into thier legs