The nests of different birds are very different. Please tell me where these differences are reflected.

Different birds have very different nests. It is true that, like swallows, their nests are very strong and can be called masters of architecture.

Then, like some other bird's nests, it is simpler to build, that is, a bird's nest.

bird

Birds are usually egg-laying animals with feathers and high metabolic rate. Most of their long bones are hollow, so most birds can fly. Birds evolved from reptiles. There are more than 9,000 kinds of birds in the world, all of which have wings and feathers, even those birds (such as ostriches and penguins) that have lost the ability to fly. The earliest birds appeared1.500 million years ago.

The body is spindle-shaped, the forelimbs are specialized into wings, the body surface has feathers, the body temperature is constant, the muscles and chest are developed, the bones are healed, and the brain is developed. You can use the air bag for double breathing, and you can lose weight without bladder. These physical characteristics are very suitable for flying. Birds have no teeth, but they have horny beaks, which can be used for hunting, nesting and combing feathers. Birds are good at building nests. They can build all kinds of nests with all kinds of materials collected. Birds are a subclass of vertebrates in taxonomy. feather

Birds are the only feathered animals on the earth. Most of the bird's body surface is covered with feathers, which can not only keep the bird's body temperature constant, but also make the bird fly. Birds have different feathers.

structure

There is a hard shaft in the center of a feather, which is called a feather shaft, the upper part of a feather is called a feather shaft, and the lower part of a feather inserted into the skin is called a feather root. There are feathers on both sides of the stem, which are composed of a tough substance called keratin. Feathers are composed of feather branches and branchlets.

grow

Feathers grow from feather follicles on the skin of birds, and the parts are combined in a special way. Most birds molt at least once a year, that is, new feathers grow and old feathers fall off. Birds molt to restore their damaged feathers.

new hand

Birds generally molt twice a year, which shows that feathers have strong regeneration ability. Scientific research shows that feather stem cells are distributed on the wall of feather follicles, which can proliferate and differentiate, and the differentiated cells grow up to produce feathers. The proliferation and differentiation of feather stem cells make the whole feather organ of birds grow and regenerate continuously.

type

Birds' feathers can be roughly divided into four types: body feathers, down feathers, tail feathers and wing feathers.

Feathers cover the whole body, forming a smooth streamlined body surface of birds; Fluffy feathers can keep warm air from dispersing quickly; Tail feathers and wing feathers are powerful and used for flight.