What does the term vertebrate mean?

The term vertebrate refers specifically to animals that possess a jointed backbone, also known as a vertebral column or spine. This backbone is a critical structural feature that provides support and protects the spinal cord, which is part of the central nervous system. Vertebrates are classified within the subphylum Vertebrata and include a diverse range of animals such as mammals, birds, reptiles, amphibians, and fish. The presence of a backbone allows for greater size, complexity, and mobility compared to their invertebrate counterparts.

The other choices do not accurately define vertebrates. For instance, while some vertebrates do lay eggs (like birds and reptiles), not all vertebrates do. Others, such as mammals, may give live birth. Additionally, invertebrates are defined as animals without a backbone, which directly opposes the definition of vertebrates. The concept of being warm-blooded is also not exclusive to vertebrates, as it pertains to their ability to regulate body temperature, which is primarily applicable to certain groups within vertebrates. Thus, the correct identification of vertebrates as animals with a jointed backbone is essential for understanding this classification in biology.