Birds have wings which are more or less developed depending on the species; the only known groups without wings are the extinct moa and elephant birds. Wings, which evolved from forelimbs, gave birds the ability to fly, although further evolution has led to the loss of flight in flightless birds, including ratites, penguins, and diverse endemic island species of birds. The digestive and respiratory systems of birds are also uniquely adapted for flight. Some bird species of aquatic environments, particularly seabirds and some waterbirds, have further evolved for swimming.
圖片編號:
93931369
拍攝者:
GitanaMedia
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授權類型 | 尺寸 | 像素 | 格式 | 點數 | |
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標準授權 | XS | 480 x 360 | JPG | 13 | |
標準授權 | S | 800 x 600 | JPG | 15 | |
標準授權 | M | 2000 x 1500 | JPG | 18 | |
標準授權 | L | 2581 x 1936 | JPG | 20 | |
標準授權 | XL | 3265 x 2449 | JPG | 22 | |
標準授權 | MAX | 4608 x 3456 | JPG | 23 | |
標準授權 | TIFF | 6517 x 4888 | TIF | 39 | |
進階授權 | WEL | 4608 x 3456 | JPG | 88 | |
進階授權 | PEL | 4608 x 3456 | JPG | 88 | |
進階授權 | UEL | 4608 x 3456 | JPG | 88 |
XS
S
M
L
XL
MAX
TIFF
WEL
PEL
UEL
標準授權 | 480 x 360 px | JPG | 13 點 |
標準授權 | 800 x 600 px | JPG | 15 點 |
標準授權 | 2000 x 1500 px | JPG | 18 點 |
標準授權 | 2581 x 1936 px | JPG | 20 點 |
標準授權 | 3265 x 2449 px | JPG | 22 點 |
標準授權 | 4608 x 3456 px | JPG | 23 點 |
標準授權 | 6517 x 4888 px | TIF | 39 點 |
進階授權 | 4608 x 3456 px | JPG | 88 點 |
進階授權 | 4608 x 3456 px | JPG | 88 點 |
進階授權 | 4608 x 3456 px | JPG | 88 點 |