Select the invertebrate.

 - grasshopper
 - West African rubber frog
 - bald eagle
 - water buffalo
A water buffalo is a mammal. Like other mammals, a water buffalo is a vertebrate. It has a backbone.
A grasshopper is an insect. Like other insects, a grasshopper is an invertebrate. It does not have a backbone. It has an exoskeleton.
A West African rubber frog is an amphibian. Like other amphibians, a West African rubber frog is a vertebrate. It has a backbone.
A bald eagle is a bird. Like other birds, a bald eagle is a vertebrate. It has a backbone.