Select the vertebrate.

 - black widow spider
 - crystal jellyfish
 - hippopotamus
 - bull ant
A bull ant is an insect. Like other insects, a bull ant is an invertebrate. It does not have a backbone. It has an exoskeleton.
Like other jellyfishes, a crystal jellyfish is an invertebrate. It does not have a backbone. It has a soft body.
Like other spiders, a black widow spider is an invertebrate. It does not have a backbone. It has an exoskeleton.
A hippopotamus is a mammal. Like other mammals, a hippopotamus is a vertebrate. It has a backbone.