Dragonflies are predators, both in their aquatic larval stage, when they are known as nymphs or naiads, and as adults. Several years of their lives are spent as nymphs living in fresh water; the adults may be on the wing for just a few days or weeks. They are fast, agile fliers, sometimes migrating across oceans, and are often found near water. They have a uniquely complex mode of reproduction involving indirect insemination, delayed fertilization, and sperm competition. During mating, the male grasps the female at the back of the head or on the prothorax, and the female curls her abdomen under her body to pick up sperm from the male`s secondary genitalia at the front of his abdomen, forming the `heart` or `wheel` posture. Loss of wetland habitat threatens dragonfly populations around the world.
圖片編號:
94055180
拍攝者:
Chriskiely
點數下載
授權類型 | 尺寸 | 像素 | 格式 | 點數 | |
---|---|---|---|---|---|
標準授權 | XS | 480 x 320 | JPG | 13 | |
標準授權 | S | 800 x 534 | JPG | 15 | |
標準授權 | M | 2119 x 1415 | JPG | 18 | |
標準授權 | L | 3104 x 2072 | JPG | 20 | |
標準授權 | XL | 3461 x 2310 | JPG | 22 | |
標準授權 | MAX | 4239 x 2830 | JPG | 23 | |
標準授權 | TIFF | 4390 x 2930 | TIF | 39 | |
進階授權 | UEL | 4239 x 2830 | JPG | 88 |
XS
S
M
L
XL
MAX
TIFF
UEL
標準授權 | 480 x 320 px | JPG | 13 點 |
標準授權 | 800 x 534 px | JPG | 15 點 |
標準授權 | 2119 x 1415 px | JPG | 18 點 |
標準授權 | 3104 x 2072 px | JPG | 20 點 |
標準授權 | 3461 x 2310 px | JPG | 22 點 |
標準授權 | 4239 x 2830 px | JPG | 23 點 |
標準授權 | 4390 x 2930 px | TIF | 39 點 |
進階授權 | 4239 x 2830 px | JPG | 88 點 |