selkärankaisten

Selkärankaisten, also known as the Sarcopterygii, is a superorder of ray-finned fish that includes the lobe-finned fish and their extinct relatives. This group is characterized by the presence of a notochord, a flexible rod that runs along the back of the embryo, which is a key feature of chordates. Selkärankaisten fish have a swim bladder, which helps them control their buoyancy, and they possess paired fins, which are a characteristic feature of actinopterygii, a subclass of ray-finned fish.

The superorder Selkärankaisten is further divided into two main groups: the Actinopterygii, which includes most modern ray-finned fish, and the Sarcopterygii, which includes the lobe-finned fish. The lobe-finned fish are further divided into two groups: the Coelacanthiformes, which includes the coelacanth, and the Dipnoi, which includes the lungfish. The coelacanth was thought to be extinct until it was rediscovered in the 1930s, and lungfish are the only living representatives of the lobe-finned fish.

Selkärankaisten fish are found in a wide variety of habitats, including freshwater, brackish water, and marine environments. They play an important role in many ecosystems, serving as both prey and predator. Some species of Selkärankaisten fish are also of commercial importance, with many being caught for food or used in aquaculture. However, many species are threatened by habitat destruction, pollution, and overfishing, and conservation efforts are underway to protect these important fish.