Is a rattlesnake a vertebrate or an invertebrate?

Answer 1

No. All reptiles, including snakes, are vertebrates. They all have backbones. They have all the organs we do (except some snakes only have one lung).

EDIT: All snakes have one functional lung and most have a vestigial left lung.

Answer 2

All snakes are vertebrates, which means they have a spine but of course no arms and legs. Snakes have a very long spine and lots of rib bones, which gives them a long tubular appearance.