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 varies: many species practice internal fertilization with males using claspers; offspring may be oviparous (egg-laying), ovoviviparous (young hatch inside the mother), or viviparous (live birth, sometimes with a placental connection). Lifespans are long in many species, and populations tend to recover slowly due to late maturity and low annual reproductive output.

The fossil record of cartilaginous fishes extends back hundreds of millions of years, with early forms appearing in the Paleozoic. Ecologically, broskväxen play key roles as predators and scavengers, influencing marine community structure. They also hold economic importance for fisheries and tourism. Many species are threatened by overfishing, bycatch, habitat loss and pollution, leading to conservation measures such as fishing quotas, protected areas, and trade controls on products like fins and cartilage.