1. Hexabranchia: 1st order of Chondrichthyes. There are only about 4 species in 1 family and 3 genera in the family Hexagillidae. There are 3 genera and 3 species in China. The structure is original. There are 6 to 7 gill openings. The eyes have no nictitating membrane or folds.

There are blowholes. One dorsal fin, no spines, positioned posteriorly, with anal fin; the axial bone of the pectoral fin extends to the front edge of the fin, and the front fin cartilage has no radial rays. The segmentation of the spine is incomplete, but the vertebral bodies are somewhat calcified, and the notochord is partially or not constricted. 1 kiss cartilage.

2. The order Porphyra: The order Porphyra, also known as the order Mackerel, is the largest order in the superorder Pleurospora. Including most modern species. There are 5 pairs of gill openings. There are 2 dorsal fins, no spines, and anal fins. The eyes have no nictitating membrane or folds. The vertebral body has radial calcification areas, and there are 4 non-calcification areas without calcification spoke invasion.

In the maxillolingual joint type, the maxilla is connected to the skull only by ligaments. Distributed in tropical and temperate zones of all oceans, it generally lives in open ocean areas, but often enters inland waters. It eats a lot, and its food includes fish, turtles, seabirds, sea lions, debris discarded from ships, etc. It is considered more dangerous to humans than other sharks.

3. Tiger shark order: an order of the Chondrichthyan class Elasmobranchia. There are only 1 family, 1 genus and 8 species. The body is thick and short, and the head is nearly square. The snout is short and blunt, the eyes are small, oval, and positioned upward.

The nostrils have a nasal groove. The mouth is flat and horizontal, with well-developed upper and lower lip folds. The upper and lower jaw teeth are of the same shape, and the front and back teeth of each jaw are shaped differently. The front teeth are thin and pointed, with 3 to 5 tooth heads; the rear teeth are flat and molar-like. The blowhole is small and located behind and below the eye.

4. Carcharhinidae: 1st order of the Chondrichthyes. 2 dorsal fins, no spines. With anal fin. There are 5 gill openings. Maxillolingual joint type. 3 kissing cartilages. The eyes have nictitating folds or membranes.

The vertebral body has radial calcified areas, and calcified spokes invade four non-calcified areas. The spiral valves of the intestine are spiral or scroll-shaped. There are more than 200 species in 4 suborders, 7 families, 49 genera in the world. China has more than 60 species in 4 suborders, 4 families, 23 genera, and is the group with the most genera and species among cartilaginous fishes in China.

5. Squalia: an order of the Chondrichthyan class Elasmobranchia. There are 87 species in 3 families, 21 genera. 2 dorsal fins, with or without hard spines; anal fin missing. There are 5 gill openings, and the vertebral body is annular or multi-annular. 1 kiss cartilage. Mainly distributed in warm water, cold water areas or deep sea areas around the world.

6. Sawshark order: 1 order of the cartilaginous fish class Elasmobranchia. This order only has 5 species in 1 family, 2 genera and 1 family in the family Sawsharkidae. There is only one species in China.