Vertebrants

Vertebrants are a group of animals that possess a backbone, or vertebral column, which provides structural support and protection for the spinal cord. This characteristic is a defining feature of the phylum Chordata, of which vertebrants are a subphylum. The backbone is composed of individual vertebrae, which are connected by intervertebral discs and ligaments, allowing for flexibility and movement.

Vertebrants are further divided into two main classes: jawless fish and jawed vertebrates. Jawless fish, such as hagfish and lampreys, are the most primitive living vertebrates. They lack paired fins, scales, and a bony skeleton, but they do possess a notochord, a flexible rod that runs along the length of the body and serves as an early form of the backbone.

Jawed vertebrates, on the other hand, possess a more complex anatomy. They have a skull that supports a pair of jaws, which contain teeth. This adaptation allows for more efficient feeding and the evolution of more complex ecosystems. Jawed vertebrates are further divided into two subclasses: cartilaginous fish and bony fish. Cartilaginous fish, such as sharks and rays, have a skeleton made of cartilage, while bony fish, such as tuna and salmon, have a skeleton made of bone.

Vertebrants have been around for over 500 million years, and they have evolved into a wide variety of forms, from the tiny, transparent lanternfish to the massive, blue whale. They are found in virtually every habitat on Earth, from the deepest parts of the ocean to the highest peaks of the mountains. Despite their diversity, all vertebrants share a common ancestor and a set of basic physiological and anatomical features.