How do snakes 'see' in the dark? Researchers have an answer
New insights explain how snakes convert infrared radiation into
electrical signals

Date:
October 21, 2020
Source:
University of Houston
Summary:
Certain species of snake -- think pit vipers, boa constrictors
and pythons, among others -- are able to find and capture prey
with uncanny accuracy, even in total darkness. Now scientists have
discovered how these creatures are able to convert the heat from
organisms that are warmer than their ambient surroundings into
electrical signals, allowing them to 'see' in the dark.



FULL STORY ========================================================================== Certain species of snake -- think pit vipers, boa constrictors and
pythons, among others -- are able to find and capture prey with uncanny accuracy, even in total darkness. Now scientists have discovered how
these creatures are able to convert the heat from organisms that are
warmer than their ambient surroundings into electrical signals, allowing
them to "see" in the dark.


==========================================================================
The work, published in the journal Matter, provides a new explanation
for how that process works, building upon the researchers' previous
work to induce pyroelectric qualities in soft materials, allowing them
to generate an electric charge in response to mechanical stress.

Researchers have known electrical activity was likely to be involved
in allowing the snakes to detect prey with such exceptional skill, said
Pradeep Sharma, M.D. Anderson Chair Professor of mechanical engineering
at the University of Houston and corresponding author for the paper. But naturally occurring pyroelectric materials are rare, and they are usually
hard and brittle. The cells in the pit organ -- a hollow chamber enclosed
by a thin membrane, known to play a key role in allowing snakes to detect
even small temperature variations -- aren't pyroelectric materials, said Sharma, who also is chairman of the Department of Mechanical Engineering
at UH.

But when he and colleagues last year reported producing pyroelectric
effects in a soft, rubbery material, something clicked.

"We realized that there is a mystery going on in the snake world,"
he said.

"Some snakes can see in total darkness. It would be easily explained
if the snakes had a pyroelectric material in their bodies, but they
do not. We realized that the principle behind the soft material we
had modeled probably explains it." Not all snakes have the ability
to produce a thermal image in the dark. But those with a pit organ are
able to use it as an antenna of sorts to detect the infrared radiation emanating from organisms or objects that are warmer than the surrounding atmosphere. They then process the infrared radiation to form a thermal
image, although the mechanism by which that happened hasn't been clear.

Sharma and his colleagues determined that the cells inside the pit organ membrane have the ability to function as a pyroelectric material, drawing
upon the electrical voltage that is found in most cells. Through modeling,
they used their proposed mechanism to explain previous experimental
findings related to the process.

"The fact that these cells can act like a pyroelectric material, that's
the missing connection to explain their vision," Sharma said.

This work was part of the Ph.D. dissertation of Faezeh Darbaniyan,
first author on the paper. Additional researchers on the project include
Kosar Mozaffari, a student at UH, and Professor Liping Liu of Rutgers University.

The work explains the mechanism by which the cells are able to take
on pyroelectric properties, although questions remain, including how
the proposed mechanism is related to the role played by the increased
number of ion channels found in TRPA1 proteins. TRPA1 proteins are more abundant in the cells of pit- organ snakes than in non-pit snakes.

"Our mechanism is very robust and simple. It explains quite a lot,"
Sharma said. "At the same time, it is undeniable these channels play a
role as well, and we are not yet sure of the connection."

========================================================================== Story Source: Materials provided by University_of_Houston. Original
written by Jeannie Kever.

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Darbaniyan et al. Soft matter mechanics and the mechanisms
underpinning
the infrared vision of snakes. Matter, 2020 DOI: 10.1016/
j.matt.2020.09.023 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201021130125.htm

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