Which of the following terms refers to animals with backbones?

The term that refers to animals with backbones is "vertebrates." Vertebrates are characterized by having a spine or backbone, which is part of a complex skeletal structure that supports the body and protects the spinal cord. This group includes mammals, birds, reptiles, amphibians, and fish.

Invertebrates, by contrast, are animals that do not have a backbone or spinal column, comprising a vast majority of animal species, including insects, arachnids, mollusks, and crustaceans.

Endotherms are organisms that can regulate their body temperature internally, typically maintaining a stable internal temperature regardless of external conditions, often referred to as warm-blooded animals. This group includes most mammals and birds.

Ectotherms are animals that depend on external environmental conditions to regulate their body temperature, often referred to as cold-blooded animals. This includes reptiles, amphibians, and most fish.

Thus, the identification of vertebrates is foundational in biology and ecology, highlighting the significance of their structural complexity and evolutionary adaptations.