Why are airplains and birds have stremlined?

Answer 1

Birds are streamlined because all species of birds that ever existed and were

NOT streamlined were unable to outfly the streamlined predators, so they got

caught and eaten, laid very few eggs, had very few hatchlings, and became

extinct.

Airplanes are streamlined because that design reduces aerodynamic drag,

which directly subtracts from thrust. So a streamlined airplane uses much

less fuel than a square airplane does to cover the same distance. Once this

fact became generally known, nobody would buy any square airplanes, and

the companies that built them went out of business. A lot like the birds.

Answer 2

Because they are created that way