These are the sharks and rays. Chordata the phylum of animals that is characterized by elongated bilaterally symmetrical bodies. In some phase of their life cycle, they have a notochord and gill slits or pouches. Chordates also often have a head, a tail, and a digestive system with an opening at both ends of the body . The Chordata include fish, amphibians, reptiles, birds, mammals , and 2 invertebrate subphyla.
Humans are members of the class Mammalia .
Convergent evolution is also referred to as convergence. These terms are illustrated in the photo on the right. Body parts on the sides of a body are referred to as being lateral . If something is along the longitudinal midline of a body, it is medial . They are usually seen in terms of being food getting opportunities in the environment.