Ruby-throated Hummingbirds’ tongues are not simple straws. They are shapeshifting, liquid trapping and transport, nectar pumping devices.
The tongue’s tip is forked and can spread and close. There are two grooves in each tip that expand when the tips are open and flattened. The grooves compress and create tube-like structures when the tongue is retracted and the tips spring closed.
The tip forks are covered with curved hair-like extensions call lamellae. It is the lamellae that initiate and control the ‘shapeshifting’ of the tongue’s tip – spreading of the fork tips and change in shape of the grooves. When the lamellae contact liquid they unfurl. This unfurling opens the fork tips and enlarges the grooves.
When the tongue is retracted the lamellae refurl and traps two tubes of nectar, one each inside each tongue tip’s groove which close into a tube-shaped liquid trap. The nectar is delivered to the esophagus for ingestion by the squeezing and slightly flattening of the tongue as it is pulled into the bill and coiled around the skull. This coiling is necessary because the tongue is 1.5 times longer than the bill when fully extended.
This pumping action can cycle as high as thirteen times per second. All while the hummingbird is hovering!
Adding to this marvel of engineering is the fact that this highly efficient pump is not muscular. In keeping with the overriding biological requirement to minimize the bird’s weight, the tongue’s transformation and liquid trapping properties are driven by fluid and gaseous forces inside the nectar reservoir acting directly on the tongue.
Capturing this action inside a blossom is not possible, but this female visiting our yard was kind enough to trap and lap sugar water from drops on the outside of an overfilled feeder.
