The domestic cat, Felis catus, is often a source of confusion when people first consider the broad categories of biological classification. The simple, direct answer to whether a cat is an invertebrate is no; cats are firmly classified as vertebrates. This initial distinction helps place the animal within the vast tree of life. Understanding this classification requires defining the two major groups into which the animal kingdom is divided.
Defining Vertebrates and Invertebrates
The fundamental difference between vertebrates and invertebrates lies in the presence or absence of a spinal column, or backbone. Vertebrates are animals that possess this vertebral column, which is part of a well-developed internal skeleton (endoskeleton). This internal bony structure supports the body and provides protection for the central nervous system, including the spinal cord.
Invertebrates are defined as animals that lack this spinal column. This group is incredibly diverse and includes the vast majority of animal species on Earth, such as insects, worms, and jellyfish. While they lack a backbone, many invertebrates rely on a rigid external covering (exoskeleton) for body support and protection, while others may have soft, unsupported bodies.
The presence of a skull is another defining feature, as the vertebrate’s brain is enclosed and protected by this structure. Invertebrates typically have simpler nervous systems that are not protected by a bony cranium. This structural difference accounts for functional disparities between the two groups, including body size and complexity.
The Biological Classification of Cats
Cats are classified as vertebrates because they possess the defining anatomical features of the group. The domestic cat has a complex skeletal structure that includes a skull and a segmented spinal column. This backbone is made up of individual bones called vertebrae, which provides a flexible yet strong central axis for the body.
The specific taxonomic placement confirms the cat’s status as a vertebrate. Cats belong to the Phylum Chordata, which includes all animals that possess a notochord or spinal column at some point in their development. They are placed in the subphylum Vertebrata and the Class Mammalia.
Being a mammal means the cat shares other characteristics with vertebrates such as humans, dogs, and whales. These include having hair, possessing mammary glands to feed their young, and maintaining a constant body temperature. This classification places the cat within the small percentage of animal life that possesses a complete internal skeleton and a backbone.