How Elephants Listen…With Their Feet | Deep Look

Thanks to Curiosity Stream for supporting
PBS Digital Studios. A rumble sounds on the African savannah. The matriarch speaks, urging the herd to leave
the watering hole. But the message reaches more than her own
kin. Other elephants, too far off for the sound
to reach their ears, get the message, too… …with their feet. A half hour’s march away, a rival matriarch
directs her own clan to the watering hole now that she knows it’s free. A roving, solitary bull starts to move towards
the matriarch’s call too, hoping to find a mate. Scientists call this seismic communication. It’s how the world’s largest land animals
keep tabs on each other in a place where eyes and ears aren’t always enough. With vocal chords eight times the size of
ours, elephants send out two types of sound waves at once. There are the high frequency ones. Those travel quickly through the air and land
on the ear. They only go a short distance, about a mile
or so. The second are low-frequency waves. They move through the earth, and travel much
further — at least 5 or 6 miles. When elephants sense one of these low rumbles,
they halt, and press their heavily-padded feet to the ground. That padding, a huge ball of fat called a
digital cushion, spreads out as much as 20 percent. Dozens of touch receptors in the elephant’s
foot, called Pacinian corpuscles, pick up these vibrations and send a signal to brain. But hold up, is that hearing or is it feeling? Well, turns out the line between those two
senses is pretty fuzzy. Scientists think ground vibrations also travel
through the elephant’s skeleton, all the way to the ear. That’s how feeling becomes hearing. Caitlin O’Connell researches hearing at
the Stanford University School of Medicine. In a series of experiments in Namibia, she
buried speakers in the ground. Then she played common elephant calls, to
see what would happen. When this herd hears an alarm call played
from an above-ground speaker, it means danger is close, they retreat. But when the same call is played underground,
they react more slowly. They grow wary and close ranks — but stay
put. When the elephants get the message through
their feet only, it means the danger is far away. Even an elephant’s footsteps transmit useful
information about its size and whereabouts to other elephants. So if you know how to listen, this dramatic
landscape hums with signals, and a web of sound holds a whole community together. Curiosity stream is a subscription streaming
service that offers documentaries and nonfiction titles from a variety of filmmakers, including
Curiosity Stream originals. You can learn more at
slash Deep Look, and use the code Deep Look during the signup process. These elephants live in a private refuge near
San Andreas, California, In the wild, African elephants walk for roughly 18 hours a day — that naturally wears down their foot pads. So here at the refuge, at least once a month,
they get a pedicure. So go ahead, pamper yourself. Subscribe to Deep Look. We’ve got new episodes every two weeks. See you next time!


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