1. A backbone (vertebrae): Vertebrates are distinguished from other animals by the presence of a backbone, or vertebrae. The backbone provides support and protection for the spinal cord and other internal organs.
2. A skull: Vertebrates also have a skull, which protects the brain.
3. A closed circulatory system: Vertebrates have a closed circulatory system, in which blood is contained within vessels.
4. A muscular system: Vertebrates have a muscular system, which allows them to move.
5. A digestive system: Vertebrates have a digestive system, which allows them to break down food and absorb nutrients.
6. A respiratory system: Vertebrates have a respiratory system, which allows them to breathe oxygen and release carbon dioxide.
7. An excretory system: Vertebrates have an excretory system, which allows them to remove waste products from the body.
8. A nervous system: Vertebrates have a nervous system, which allows them to sense their environment and respond to stimuli.
9. A reproductive system: Vertebrates have a reproductive system, which allows them to reproduce.
These unique characteristics have allowed vertebrates to become the dominant group of animals on Earth. They are found in a wide range of habitats, from the oceans to the mountains, and they play a variety of roles in the ecosystem.