Their shape. Peace out. :)
Their shape and aerodynamic efficiency makes them streamlined.
so that they can move smoothly
Because streamlined body cuts air and allows birds to move swiftly in air.
Fish, birds and snakes are a few
so that the car will go faster and thecorners and the distence from the ground makes it streamlined .The rounder the corners the more streamlined it is
Penguins do not have kneecaps, because they do not need them. Not having kneecaps makes them more streamlined than other birds, which they need to be to be fast enough to catch their food.
makes them better streamlined i would guess
It's shape.
When flying, the birds need power on the wing to fly. Their bodies should also be streamlined.
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.
Birds' contour feathers are responsible for giving them their streamlined shape, which helps reduce drag during flight. Coloration in birds comes from a combination of pigments in the feathers as well as structural colors created by the arrangement of the feathers themselves.
Sharks, Tuna, Mackerels, and Marlins are all examples of Streamlined body shape fishes.