Por que o mosquito pica mais umas pessoas do que outras? — Transcript

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1. 0:00Why do mosquitoes bite some people more
2. 0:02than others? If you were a female
3. 0:04mosquito, you could live just on flower
4. 0:05nectar. But to make eggs, you need
5. 0:07protein, and flowers have almost none.
6. 0:10So you go after blood. That is why only
7. 0:13the female bites. The male spends his
8. 0:15life sipping from flowers. But it's
9. 0:17night, and you are the size of a grain
10. 0:19of rice. So you follow the breath.
11. 0:22Every time someone breathes, they
12. 0:23release an invisible gas called carbon
13. 0:25dioxide. You can sense this gas from
14. 0:27over 10 meters away. That is why the
15. 0:29buzzing comes right to your ear. The
16. 0:31mosquito follows your breath right to
17. 0:33your face. The breath leads you to a
18. 0:37tent with two friends sleeping. You
19. 0:39smell both and choose him. Why him? The
20. 0:42answer is kind of gross. I'll get to
21. 0:44that soon. But to you, skin is thick
22. 0:47like leather. So your snout isn't just
23. 0:49one needle. There are six, kept in a
24. 0:52little case. Four saw and hold the skin
25. 0:55open. One tube pulls blood and the
26. 0:57other spits, and the tip bends under
27. 0:59the skin, hunting for a vessel. This
28. 1:02needle-filled snout is called a
29. 1:04proboscis, but blood outside the body
30. 1:06hardens quickly. That is how a wound
31. 1:09closes. So you spit saliva that stops
32. 1:11the blood from hardening. A saliva
33. 1:14called an anticoagulant, and that is
34. 1:16what itches. The itch isn't from the
35. 1:19puncture, it's his body fighting your
36. 1:21spit. But you drink until you're three
37. 1:23times heavier and can barely take off.
38. 1:26So you release the watery part while
39. 1:27you drink. Yes, the malaria mosquito
40. 1:30pees on who it's biting, but with a
41. 1:32full belly, you need a place for the
42. 1:34eggs. So you look for stagnant water,
43. 1:37old tires, plant saucers, bottle caps.
44. 1:40The place where the mosquito is born is
45. 1:42called a breeding ground. The dengue
46. 1:44mosquito's egg can last up to a year
47. 1:46dry, waiting for rain. That is why they
48. 1:48tell you to turn the bottle cap over.
49. 1:49An inch of water is enough to become a
50. 1:51nursery. Meanwhile, he wakes up
51. 1:54squirming from so much itching. And the
52. 1:57friend next to him, not a single bite.
53. 2:00And it's not about "sweet blood." You
54. 2:01only taste the blood after biting. What
55. 2:03attracts you is a sour scent that skin
56. 2:05bacteria release. Some people release a
57. 2:07lot more of it. This is the smell of
58. 2:09the skin. In one study, those who were
59. 2:11the favorites stayed that way for years
60. 2:13. And some mosquitoes like foot odor so
61. 2:15much they even go after stinky cheese.
62. 2:18But now you go back to being human and
63. 2:20want to sleep in peace. So you turn on
64. 2:22the fan. The mosquito flies at about 1
65. 2:25mph, losing to the wind that still
66. 2:27spreads your scent. And repellent
67. 2:30doesn't kill anything. It confuses the
68. 2:32mosquito's sense of smell and you
69. 2:33vanish from its map. On the outside,
70. 2:36it's just an annoying buzz in your ear.
71. 2:39On the inside, it's a scent tracker
72. 2:41following your breath, six needles
73. 2:42sawing skin, and spit that leaves an
74. 2:44itchy souvenir. Send this to that
75. 2:47person who's always getting bitten and
76. 2:48follows "Deconstructing the Universe"
77. 2:50to boost their IQ. M.