Answer:
phylum Chordata.
Step-by-step explanation:
The phylum Chordata is a diverse group of animals that share the presence of a notochord, a flexible rod-like structure that provides support and gives rise to the spine or vertebral column in most members of the phylum. This characteristic feature of having a spine is what defines the animals in this group.
Examples of animals in the phylum Chordata include mammals, birds, reptiles, amphibians, and fish. These animals exhibit a wide range of physical characteristics and behaviors, but they all share the common feature of having a spine.
The presence of a spine allows for structural support, protection of the nervous system, and facilitates movement and coordination in these animals. It is an important evolutionary adaptation that has contributed to the success and diversity of the Chordata phylum.