Paper, Suction Feeding by Elephants

Despite having a trunk that weighs over 100 kg, elephants mainly feed on
lightweight vegetation. How do elephants manipulate such small items?
In this experimental and theoretical investigation, we filmed elephants at
Zoo Atlanta showing that they can use suction to grab food, performing a
behaviour that was previously thought to be restricted to fishes. We use
a mathematical model to show that an elephant’s nostril size and lung
capacity enables them to grab items using comparable pressures as the
human lung. Ultrasonographic imaging of the elephant sucking viscous
fluids show that the elephant’s nostrils dilate up to 30% in radius, which
increases the nasal volume by 64%. Based on the pressures applied, we estimate
that the elephants can inhale at speeds of over 150 m s−1, nearly
30 times the speed of a human sneeze. These high air speeds enable the elephant
to vacuum up piles of rutabaga cubes as well as fragile tortilla chips.
We hope these findings inspire further work in suction-based manipulation
in both animals and robots.

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