Featured Research

from universities, journals, and other organizations

Snakes Locate Prey Through Vibration Waves

Date:
February 25, 2008
Source:
Technical University Munich
Summary:
It is often believed that snakes cannot hear. This presumption is fed by the fact that snakes lack an outer ear and that scientific evidence of snakes responding to sound is scarce. Snakes do, however, possess an inner ear with a functional cochlea. Scientists now present evidence that snakes use this structure to detect minute vibrations of the sand surface that are caused by prey moving. Their ears are sensitive enough to not only "hear" the prey approaching, but also to allow the brain, i.e., the auditory system, to localize the direction it is coming from.

It is often believed that snakes cannot hear. Snakes do, however, possess an inner ear with a functional cochlea.
Credit: iStockphoto

It is often believed that snakes cannot hear. This presumption is fed by the fact that snakes lack an outer ear and that scientific evidence of snakes responding to sound is scarce. Snakes do, however, possess an inner ear with a functional cochlea.

In a recent article in Physical Review Letters* scientists from the Technical University Munich (TUM), Germany, and the Bernstein Center for Computational Neuroscience (BCCN) present evidence that snakes use this structure to detect minute vibrations of the sand surface that are caused by prey moving. Their ears are sensitive enough to not only “hear” the prey approaching, but also to allow the brain, i.e., the auditory system, to localize the direction it is coming from. The work was carried out by J. Leo van Hemmen and Paul Friedel, scientists at the Biophysics Department of the TUM and BCCN, together with their colleague Bruce Young from the Biology Department of Washburn University at Topeka (KS, USA).

Any disturbance at a sandy surface leads to vibration waves that radiate away from the source along the surface. These waves behave just like ripples on the surface of a pond after a stone is dropped into the water. The sand waves, however, propagate much quicker (the speed is about 50 meters per second) than at the water surface but on the other hand much more slowly than for instance in stone (or concrete) and the amplitude of the waves may be as small as a couple of thousands of a millimeter.

Yet a snake can detect these small ripples. If it rests its head on the ground, the two sides of the lower jaw are brought into vibration by the incoming wave. These vibrations are then transmitted directly into the inner ear by means of a chain of bones attached to the lower jaw. This process is comparable to the transmission of auditory signals by the ossicles in the human middle ear. The snake thus literally hears surface vibrations.

Mammals and birds can localize a sound source by comparing the arrival times of sounds that arrive at the right and left ear through air. For sound coming from the right, the right ear will respond a fraction of a second earlier than the left ear. For sound coming from the left, the situation is exactly the other way around. From this time-of-arrival difference, the brain computes the direction that the sound comes from.

Combining approaches from biomechanics and naval engineering with the modeling of neuronal circuits, Friedel and his colleagues have shown that the snake can use its ears to perform the same trick for sound arriving through sand. The left and right side of the lower jaw of a snake are not rigidly coupled. Rather, they are connected by flexible ligaments that enable the snake to stretch its mouth enormously to swallow large prey. Both sides of the jaw can thus move independently, just like two boats floating - so to speak - on a sea of sand, and in this way allow for stereo hearing.

A sand wave originating from the right will stimulate the right side of the lower jaw slightly earlier than the left side, and vice versa. Using a mathematical model, the scientists calculated the vibration response of the jaw to an incoming surface wave. They could show that the small difference in the arrival time of the wave at the right and the left ear is sufficient for the snake's brain to calculate the direction of the sound source.

The extraordinary flexibility of the lower jaw of snakes has evolved because being able to swallow very large meals is a big advantage if food is in short supply and competition fierce. Moreover, the separation of the sides of the lower jaw also allowed this very interesting form of hearing to develop.

*Auditory localization of ground-borne vibrations in snakes. Physical Review Letters 100, 048701 (2008). doi: 10.1103/PhysRevLett.100.048701

Paul Friedel1, Bruce A. Young2, and J. Leo van Hemmen1

  1. Physik Department T35, Technical University Munich, Garching (Germany) & Bernstein Center for Computational Neuroscience – Munich (Germany)
  2. Department of Biology, Washburn University, Topeka (KS, USA)

Story Source:

The above story is based on materials provided by Technical University Munich. Note: Materials may be edited for content and length.


Cite This Page:

Technical University Munich. "Snakes Locate Prey Through Vibration Waves." ScienceDaily. ScienceDaily, 25 February 2008. <www.sciencedaily.com/releases/2008/02/080221105350.htm>.
Technical University Munich. (2008, February 25). Snakes Locate Prey Through Vibration Waves. ScienceDaily. Retrieved October 21, 2014 from www.sciencedaily.com/releases/2008/02/080221105350.htm
Technical University Munich. "Snakes Locate Prey Through Vibration Waves." ScienceDaily. www.sciencedaily.com/releases/2008/02/080221105350.htm (accessed October 21, 2014).

Share This



More Plants & Animals News

Tuesday, October 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

'Cadaver Dog' Sniffs out Human Remains

'Cadaver Dog' Sniffs out Human Remains

AP (Oct. 21, 2014) Where's a body buried? Buster's nose can often tell you. He's a cadaver dog, specially trained to find human remains and increasingly being used by law enforcement and accepted in courts. These dogs are helping solve even decades-old mysteries. (Oct. 21) Video provided by AP
Powered by NewsLook.com
White Lion Cubs Born in Belgrade Zoo

White Lion Cubs Born in Belgrade Zoo

AFP (Oct. 20, 2014) Two white lion cubs, an extremely rare subspecies of the African lion, were recently born at Belgrade Zoo. They are being bottle fed by zoo keepers after they were rejected by their mother after birth. Duration: 00:42 Video provided by AFP
Powered by NewsLook.com
Traditional Farming Methods Gaining Ground in Mali

Traditional Farming Methods Gaining Ground in Mali

AFP (Oct. 20, 2014) He is leading a one man agricultural revolution in Mali - Oumar Diatabe uses traditional farming methods to get the most out of his land and is teaching others across the country how to do the same. Duration: 01:44 Video provided by AFP
Powered by NewsLook.com
Goliath Spider Will Give You Nightmares

Goliath Spider Will Give You Nightmares

Buzz60 (Oct. 20, 2014) An entomologist stumbled upon a South American Goliath Birdeater. With a name like that, you know it's a terrifying creepy crawler. Sean Dowling (@SeanDowlingTV) has the details. Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins