Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help … See more

Fins can either be paired or unpaired. The pectoral and pelvic fins are paired, whereas the dorsal, anal and caudal fins are unpaired and situated along the midline of the body. For every type of fin, there are a number of f… See more

Bony fishes (Actinopterygii and Sarcopterygii) form a taxonomic group called Osteichthyes (or Euteleostomi, which includes also land vertebrates); they have skeletons made of bone mostly, and can be contrasted … See more

Cartilaginous fishes form a class of fishes called Chondrichthyes. They have skeletons made of cartilage rather than bone. The class includes sharks, rays and chimaeras.
Shark fin sk… See more

Foil shaped fins generate thrust when moved, the lift of the fin sets water or air in motion and pushes the fin in the opposite direction. Aquatic animals get significant thrust by moving fins back and forth in water. Often the … See more

There are two prevailing hypotheses that have been historically debated as models for the evolution of paired fins in fish: the gill arch theory and the lateral fin-fold theory. The former, commonly referred to as the "Gegenbau… See more