Our analysis of production and cost begins with a period economists call the short. run. Theshort run in this microeconomic context is a planning period over which the. managers of a firm must consider one or more of their factors of production as fixed.
Sharks have two sets of paired fins on the sides of their body, in the same general position as the main wings and horizontal tail wings of a plane. The shark can position these fins at different angles, changing the path of the water moving around them.
Sharks have five different kinds of fins. 1  Paired pectoral fins lift the shark as it swims. 2  Paired pelvic fins stabilize the shark. 3  One or two dorsal fins also stabilize the shark. In some species, dorsal fins have spines. 4  Not all sharks have an anal fin, but it. provides stability for the sharks that do have one.