1. Their body is flat or mace-shaped. They are jawed animals.
2. Their endoskeleton is made of cartilage.
3. Their body skin is hard and tough.
4. Body covered by placoid scales.
5. There are 5-7 pairs of gill slits on both sides of the head.
6. They do not have horns.
7. The mouth and nostrils are located at the base of the digit. There are numerous rows of placoid teeth in the jaws. Siddiq Publications
8. The body does not have air sacs or sacs.
9. The digestive system consists of a J-shaped stomach, a spiral-shaped intestine, and a fatty liver.
10. Their heart is two-chambered and known as the venus heart.
11. Caudal fin heterocercal type. That is, the caudal fin is divided into two unequal parts.
12. In male fish the pelvic fins are modified to form copulatory organ clusters.
13. They are unisexual animals. Fertilization occurs. Direct exposure. They are ovaries, ovaries or uterus. Dr. Siddiq Publications