Suction feeding by elephants

摘要

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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mn>30</mml:mn><mml:mtext>%</mml:mtext></mml:math> in radius, which increases the nasal volume by <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mn>64</mml:mn><mml:mtext>%</mml:mtext></mml:math> . 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.