Chondrichthyes as Vertebrates
Chondrichthyes, which include sharks, rays, and skates, are classified as vertebrates despite their notochord being persistent throughout life and not forming a vertebral column. This classification is based on several key characteristics:

Notochord Presence
- Chondrichthyes have a notochord that provides structural support and flexibility to their bodies. This notochord is a defining feature of chordates, the phylum to which vertebrates belong.
- In Chondrichthyes, the notochord persists throughout their lives, unlike in other vertebrates where it is replaced by a vertebral column during development.

Vertebrate Status
- Despite the notochord not forming a true vertebral column in Chondrichthyes, they still possess other vertebrate characteristics such as a dorsal nerve cord, pharyngeal slits, and a post-anal tail.
- These shared characteristics with other vertebrates place Chondrichthyes within the vertebrate group.

Evolutionary Significance
- Chondrichthyes are considered primitive vertebrates, retaining some ancestral features that have been lost or modified in more advanced vertebrates.
- The presence of a notochord in Chondrichthyes highlights their evolutionary history and their position within the vertebrate lineage.
In conclusion, despite the unique feature of a persistent notochord, Chondrichthyes are classified as vertebrates due to their overall anatomical similarities with other vertebrates and their evolutionary relationships within the animal kingdom.

Its a vertebrate as it has ventral branchial heart...