in a paper titled
1 tongues are
2 micropumps which appears in the august 19 issue of
3 of the royal society b, alejandro rico guevara and margaret rubega from the department of ecology and
4 biology and tai-hsi fan from the school of engineering, say that fluid is actually
5 into the tongue by the elastic expansion of the tongues
7 after they are squeezed flat by the
8. their data shows that fifty years of research describing how
9 and floral nectar have coevolved will have to be reconsidered.
what is actually taking place, the researcher report, is that during the offloading of the nectar inside the bill, hummingbirds compress their tongues upon
10. the compressed tongue
11 12 until it contacts the nectar surface, after which the tongue reshapes, filling
13 with nectar.
the expansive filling
14 uses the elastic recovery properties of the
6 walls to load nectar on the tongue in an order of magnitude that allows the hummingbirds to extract nectar at higher rates than are predicted by capillarity-based
15 models.
observations and measurements were taken from seven countries throughout the americas where free-living, never handled hummingbirds were feeding at modified
16 feeders simulating nectar volumes and concentrations of hummingbird pollenated flowers. the researchers measured 96 foraging
17 of 32 focal birds belonging to 18 species from seven out the nine main hummingbird clads.
收听单词发音 
