Try sucking maple syrup through a straw, and you’ll appreciate a fruit fly’s struggle to get a sip of sugar water. But a tiny system of valves and tubes works to pump fluid into a fly’s gut, researchers saw in the first X-ray videos of the insects slurping.
Scientists expected that pumping fluid would be more difficult for the fly as its gut swells up, the way inflating a bike tire requires more work as it fills with air. On top of that, fluids flowing through tubes face more resistance as they become more viscous and as the diameter of the tube shrinks. So the fact that house flies and honey bees have no problem sipping fluids thicker than ketchup through a 10-micrometer straw has puzzled researchers.
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