broskväxen
Broskväxen is the Swedish term for cartilaginous fishes, a group of jawed vertebrates in the class Chondrichthyes. They include sharks, rays and skates, as well as chimaeras. Their skeletons are made primarily of cartilage rather than bone, which provides a lighter framework and distinct buoyancy characteristics. The skin is covered with placoid scales, giving a rough texture. They lack a swim bladder and rely on body movement, fins, and in some species a large liver rich in oil to maintain buoyancy. Most species inhabit aquatic environments, from shallow coastal waters to the deep ocean, with a distribution that is worldwide but often favors temperate and tropical regions.
Broskväxen are divided into two major groups: Elasmobranchii (sharks, rays and skates) and Holocephali (chimaeras). Reproduction
The fossil record of cartilaginous fishes extends back hundreds of millions of years, with early forms appearing