NEET BIOLOGY

Detailed explanation-1: -Jawed fish include cartilaginous and bony fish. Cartilaginous fish include sharks, rays and, skates. Cartilaginous fishes have a skeleton made of cartilage, a material that is lighter and more flexible than bone. These type of fishes have movable jaws that are usually armed with well developed teeth.

Detailed explanation-2: -Along with lampreys, hagfish are jawless and are living fossils; hagfish are basal to vertebrates, and living hagfish remain similar to hagfish 300 million years ago. The classification of hagfish has been controversial.

Detailed explanation-3: -Fish typically have a powerful bite or a fast bite, but not both, the researchers said. Dunkleosteus was one of many species of placoderms, a diverse group of armored fishes that dominated aquatic ecosystems during the Devonian period, from 415 million to 360 million years ago.

Detailed explanation-4: -3.29. There are two extant groups of jawless fish: hagfish and lamprey.