What are Vertebrates?
Vertebrates are animals that have vertebrae (or “backbones” as they are commonly called). They are members of the phylum Chordata, which includes all animals that possess an organ called a notochord. In vertebrates, however, the notochord is surrounded by a series of bony growths that develop into vertebrae. In higher vertebrates, such as humans, the notochord is most readily seen in embryos and becomes almost wholly replaced by vertebrae as the animals mature. Primitive vertebrates, first known to have appeared in the Cambrian Period of the Paleozoic Era (about 525 million years ago), apparently were adapted to grazing algae in shallow ocean waters and moving about from place to place. These two early adaptations were made possible by three important vertebrate characteristics, a vertebral column (specialized for waving back and forth to allow active swimming), a brain and complex nervous system (which allowed an active animal to maneuver and keep track of its ever changing environmen
Vertebrates are animals with a backbone, also known as a spinal column. They make up most of the phylum Chordata, one among 38 animal phyla. All other phyla are exclusively invertebrate. A couple members of phylum Chordata, lancelets and tunicates, are invertebrates. Lancelets just have a notochord rather than a true spinal coumn, and tunicates only have a notochord during early development. Fish, sharks, rays, amphibians, reptiles, birds, and mammals (including humans) are vertebrates. The main evolutionary reason for the evolution of vertebrates is the need for a strong supportive structure for durability and structural integrity. The spinal column also acts as a superhighway for the nervous system, supporting greater complexity. The first vertebrates are known from fossils in the Maotianshan shales in China, dated to between 525 and 520 million years ago, during an episode of adaptive radiation called the Cambrian explosion. They are simple jawless fishes like Myllokunmingia, bearin
