1This is the deadliest animal in the world.
2Mosquitoes kill hundreds of thousands of people each year...
3the most vulnerable people: children, pregnant women...
4No other bite kills more humans...
5or makes more of us sick.
6So what makes a mosquito's bite so effective?
7For starters, they're motivated.
8Only females bite us.
9They need blood to make eggs...
10And a pool of water for their babies to hatch in.
11Even a piece of trash can hold enough.
12At first glance, it looks simple - this mosquito digging her proboscis into us.
13But the tools she's using here are sophisticated.
14First, a protective sheath retracts - see it bending back?
15If you look at a mosquito's head under a microscope, you can see what that sheath protects.
16And inside, there are six needles!
17Two of them have tiny teeth.
18She uses those to saw through the skin.
19They're so sharp you can barely feel her pushing.
20These other two needles hold the tissues apart while she works.
21From under the skin, you can see her probing, looking for a blood vessel.
22Receptors on the tip of one of her other needles pick up on chemicals that our blood vessels exude naturally and guide her to it.
23Then she uses this same needle like a straw.
24As her gut fills up, she separates water from the blood and squeezes it out.
25See that drop?
26That frees up space to stuff herself with more nutritious red blood cells.
27With another needle, she spits chemicals into us.
28They get our blood flowing more easily, and give us itchy welts afterwards.
29And sometimes, before she pries herself away, she leaves a parting gift in her saliva:
30a virus or a parasite that can sicken or kill us.
31There's nothing in it for her.
32The viruses and parasites are just hitching a ride.
33But this is what makes mortal enemies out of us and mosquitoes.
34They take our blood.
35Sometimes we take theirs.
36But often, not soon enough.