Birds adapt to life in Yu Feixiang. Their bones are light and strong, with fine bone fragments, long hollow bones and penetrating air sacs. Many bone fragments are connected together to increase their firmness. The spine can be divided into five parts: cervical vertebra, thoracic vertebra, lumbar vertebra, sacral vertebra and coccygeal vertebra. The large number of cervical vertebrae and saddle-shaped vertebral bodies make the neck extremely flexible (the owl's head can move up to 270).
The pectoral muscles related to flight in birds are particularly developed, accounting for about 1/5 of their weight. They can send out powerful forces and flap their wings. And the back muscles degenerate, contrary to fish. The muscles of the hind limbs are concentrated in the upper thighs, and each has a long tendon connected to the toes. In this way, the muscles that control the movement of forelimbs and hind limbs are concentrated in the central part of the body, which is of great significance to keep the center of gravity stable during flight.
Among the sense organs of birds, the most developed is the visual organ that plays an important role in air flight, while the olfactory organ is underdeveloped. Bird's eyes can quickly adjust their vision by relying on developed ciliary muscles, from hyperopia to myopia.
Therefore, when birds fly in trees, they never touch branches; Or dive to the ground for food from high altitude, or adjust from "hyperopia" to "myopia" in an instant. The bird's eye blink membrane is developed, which covers the eyeball during flight and plays a protective role.
Birds can fly, but not all birds can fly. For example, the ostrich's wings have degenerated, its sternum is small and flat, and there is no keel protrusion, so it can't fly. Penguins are degenerate seabirds, their wings have become fins, and they have lost the ability to fly. Although some birds can fly, they don't fly very far. For example, a chicken has short wings and can't fly high, but it can fly at least tens of meters.
However, domestic ducks have completely lost the ability to fly. Among the birds, the highest flying is the alpine vulture, which can fly above 10000 meters. Swift is the fastest flying speed, and the fastest speed of short-distance flight can reach more than 360 kilometers per hour. Returning in spring, birds began a series of activities such as courtship, breeding, nesting, hatching and brooding. Birds use their beaks to feed in the soil, and their beaks are generally long and narrow.
Extended information: The principle of airplane taking off is different from that of bird flying.
Planes are not only much heavier than birds, but also have completely different take-off principles. But like a bird, the most important thing for a plane to take off is to rely on two wings that look like bird wings.
Let dozens of tons of planes fly into the sky, and the most important thing is to skillfully use the Bernoulli principle. When liquids, gases and other fluids flow, the faster the flow velocity, the smaller the pressure, and the slower the flow velocity, the greater the pressure.
The upper surface of the wing is more curved than the lower surface. When the plane takes off through the wing, the air is divided into two parts at the leading edge, which flow through the upper and lower surfaces of the wing respectively.
At the same time, the air flowing through the upper surface travels farther than the air flowing through the lower surface, so the air on the upper surface flows faster than the air on the lower surface, which creates a pressure difference. The faster the aircraft speed, the greater the pressure difference. Acceleration to a certain extent, the pressure difference is greater than the gravity of the plane, and the plane naturally "flies".
Usually when we fly, the plane accelerates on the runway and then takes off. This is the principle. Moreover, in terms of takeoff conditions, it is best for the plane to take off against the wind. The next time a small partner flies, it must be said that it is all the way against the wind, because it is impossible to fly with the wind.
Baidu Encyclopedia-Birds (feathered oviparous vertebrates)
Science and Technology Daily-What's the difference between the flight principles of airplanes and birds?