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.
Like most fishes, sharks have two sets of paired fins (pectoral and pelvic, corresponding to arms and legs in humans) but-unlike those of bony fishes they are supported by soft, unsegmented rays called  ceratotrichia  (used in making shark-fin soup).ike most fishes, sharks have two sets of paired fins (pectoral and pelvic, corresponding to arms and legs in humans) but-unlike those of bony fishes they are supported by soft, unsegmented rays called  ceratotrichia  (used in making shark-fin soup).