The hummingbird's tongue: a self-assembling capillary syphon.
We present the results of a combined experimental and theoretical investigation of the dynamics of drinking in ruby-throated hummingbirds. In vivo observations reveal elastocapillary deformation of the hummingbird's tongue and capillary suction along its length. By developing a theoretical model for the hummingbird's drinking process, we investigate how the elastocapillarity affects the energy intake rate of the bird and how its open tongue geometry reduces resistance to nectar uptake. We note that the tongue flexibility is beneficial for accessing, transporting and unloading the nectar. We demonstrate that the hummingbird can attain the fastest nectar uptake when its tongue is roughly semicircular. Finally, we assess the relative importance of capillary suction and a recently proposed fluid trapping mechanism, and conclude that the former is important in many natural settings.
Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
Wonjung
W
Kim
François
F
Peaudecerf
Maude W
MW
Baldwin
John W M
JW
Bush
D000818:Animals; D001717:Birds / Q000033:anatomy & histology / Q000502:physiology*; D002197:Capillary Action; D004327:Drinking Behavior; D005247:Feeding Behavior; D035264:Flowers / Q000033:anatomy & histology / Q000502:physiology; D008954:Models, Biological; D057048:Plant Nectar / Q000737:chemistry; D054817:Pollination; D014059:Tongue / Q000033:anatomy & histology / Q000502:physiology*; D014741:Video Recording
D057048:Plant Nectar