Featured Research

from universities, journals, and other organizations

Snakes control blood flow to aid vision

Date:
November 4, 2013
Source:
University of Waterloo
Summary:
A new study shows that snakes can optimize their vision by controlling the blood flow in their eyes when they perceive a threat.

Instead of eyelids, snakes have a clear scale called a spectacle. It works like a window, covering and protecting their eyes. When presented with a threat, the fight-or-flight response changes the spectacle’s blood flow pattern, reducing blood flow for longer periods than at rest, up to several minutes.
Credit: Kevin van Doorn

A new study from the University of Waterloo shows that snakes can optimize their vision by controlling the blood flow in their eyes when they perceive a threat.

Kevin van Doorn, PhD, and Professor Jacob Sivak, from the Faculty of Science, discovered that the coachwhip snake's visual blood flow patterns change depending on what's in its environment. The findings appear in the most recent issue of the Journal of Experimental Biology.

"Each species' perception of the world is unique due to differences in sensory systems," said van Doorn, from the School of Optometry & Vision Science.

Instead of eyelids, snakes have a clear scale called a spectacle. It works like a window, covering and protecting their eyes. Spectacles are the result of eyelids that fuse together and become transparent during embryonic development.

When van Doorn was examining a different part of the eye, the illumination from his instrument detected something unusual.

Surprisingly, these spectacles contained a network of blood vessels, much like a blind on a window. To see if this feature obscured the snake's vision, van Doorn examined if the pattern of blood flow changed under different conditions.

When the snake was resting, the blood vessels in the spectacle constricted and dilated in a regular cycle. This rhythmic pattern repeated several times over the span of several minutes.

But when researchers presented the snake with stimuli it perceived as threatening, the fight-or-flight response changed the spectacle's blood flow pattern. The blood vessel constricted, reducing blood flow for longer periods than at rest, up to several minutes. The absence of blood cells within the vasculature guarantees the best possible visual capacity in times of greatest need.

"This work shows that the blood flow pattern in the snake spectacle is not static but rather dynamic," said van Doorn.

Next, the research team examined the blood flow pattern of the snake spectacle when the snake shed its skin. They found a third pattern. During this time, the vessels remained dilated and the blood flow stayed strong and continuous, unlike the cyclical pattern seen during resting.

Together, these experiments show the relationship between environmental stimuli and vision, as well as highlight the interesting and complex effect blood flow patterns have on visual clarity. Future research will investigate the mechanism underlying this relationship.

"This research is the perfect example of how a fortuitous discovery can redefine our understanding of the world around us," said van Doorn.


Story Source:

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


Journal Reference:

  1. K. van Doorn, J. G. Sivak. Blood flow dynamics in the snake spectacle. Journal of Experimental Biology, 2013; 216 (22): 4190 DOI: 10.1242/jeb.093658

Cite This Page:

University of Waterloo. "Snakes control blood flow to aid vision." ScienceDaily. ScienceDaily, 4 November 2013. <www.sciencedaily.com/releases/2013/11/131104142424.htm>.
University of Waterloo. (2013, November 4). Snakes control blood flow to aid vision. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2013/11/131104142424.htm
University of Waterloo. "Snakes control blood flow to aid vision." ScienceDaily. www.sciencedaily.com/releases/2013/11/131104142424.htm (accessed July 28, 2014).

Share This




More Plants & Animals News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Traditional African Dishes Teach Healthy Eating

Traditional African Dishes Teach Healthy Eating

AP (July 28, 2014) Classes are being offered nationwide to encourage African Americans to learn about cooking fresh foods based on traditional African cuisine. The program is trying to combat obesity, heart disease and other ailments often linked to diet. (July 28) Video provided by AP
Powered by NewsLook.com
Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Newsy (July 28, 2014) The asteroid that killed the dinosaurs struck at the worst time for them. A new study says that if it hit earlier or later, they might've survived. Video provided by Newsy
Powered by NewsLook.com
Raw: Sea Turtle Hatchlings Emerge from Nest

Raw: Sea Turtle Hatchlings Emerge from Nest

AP (July 27, 2014) A live-streaming webcam catches loggerhead sea turtle hatchlings emerging from a nest in the Florida Keys. (July 27) Video provided by AP
Powered by NewsLook.com
Russia Saves Gecko Sex Satellite, Media Has Some Fun With It

Russia Saves Gecko Sex Satellite, Media Has Some Fun With It

Newsy (July 27, 2014) The satellite is back under ground control after a tense few days, but with a gecko sex experiment on board, the media just couldn't help themselves. Video provided by Newsy
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:
from the past week

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