Select the vertebrate.

 - barrel jellyfish
 - redback spider
 - sea turtle
 - monarch butterfly
A monarch butterfly is an insect. Like other insects, a monarch butterfly is an invertebrate. It does not have a backbone. It has an exoskeleton.
Like other spiders, a redback spider is an invertebrate. It does not have a backbone. It has an exoskeleton.
A sea turtle is a reptile. Like other reptiles, a sea turtle is a vertebrate. It has a backbone.
Like other jellyfishes, a barrel jellyfish is an invertebrate. It does not have a backbone. It has a soft body.