Biologists find smart fish

2012-10-21 21:59
(Supplied)

(Supplied)

Multimedia   ·   User Galleries   ·   News in Pictures Send us your pictures  ·  Send us your stories

kalahari.com

Paris - Biologists reported on Sunday that silvery fish have found a smart way to get around the laws of physics so that they maintain their reflective camouflage in open water.

Sprats, sardines and herrings have a skin that neutralises the polarisation of light, enabling them to keep their protective silver cloak, they found.

Polarisation describes how light waves travel. Light that is reflected becomes horizontally polarised, meaning that the waves are all oscillating horizontally.

Under a law called the "Brewster window effect," polarisation leads to a drop in the amount of light that is reflected.

This in theory should pose a problem for shoal fish which swim in the mid-water zone, where they have to reflect light from the sky so that they meld into the background and thwart predators.

Reporting in the journal Nature Photonics, British researchers found that underneath the scales of these fish lie a remarkable layer of skin called the stratum argenteum.

It comprises alternating layers of proteins, one called guanine crystals that highly refract light, and another, called a cytoplasm, which has a low index for refracting light.

The investigators found that there were two kinds of guanine crystals, each with slightly different optical properties. Working together, rather like two refractive lenses, they neutralise polarisation.

Properties

Nicholas Roberts at Britain's University of Bristol said: "We measured how different polarisations of light were reflected from the skin and found that all polarisations were reflected the same way.

"By creating a non-polarising reflector, the fish have found a way to maximise their reflectivity over all the angles they are viewed from. This helps the fish best match the light environment of the open ocean, making them less likely to be seen."

The research opens the way to multi-layered mirrors, made from polymers, which mimic the fish skin, the scientists hope.

It could be a boost for optical fibres, which use non-polarising reflectors to enhance light transmission, said lead author Tom Jordan.

"These man-made reflectors currently require the use of materials with specific optical properties that are not always ideal.

"The mechanism that has evolved in fish overcomes this current design limitation and provides a new way to manufacture [them]."





- SAPA

Read more on:    france  |  marine life
NEXT ON NEWS24X

Read News24’s Comments Policy

24.com publishes all comments posted on articles provided that they adhere to our Comments Policy. Should you wish to report a comment for editorial review, please do so by clicking the 'Report Comment' button to the right of each comment.

Comment on this story
13 comments
Add your comment
Comment 0 characters remaining
 

Inside News24

 
 
Traffic
Lottery
 
  • Wednesday Paarl - 06:58 AM
    Road name: N1 Eastbound
    STATIONARY TRUCK in the left lane before the R101 Main Road exit
  • Wednesday Cape Town - 06:56 AM
    Road name: N2 Inbound
    DELAYS between Duinefontein Road and the M5 Highway Interchange
 
More traffic reports...
 

Jobs in Cape Town [change area]

Property [change area]

APARTMENTS / FLATS FOR SALE IN Hermanus

Apartments / Flats R 1 825 000

Travel - Look, Book, Go!

Escape winter, head to Mauritius

Escape winter by spending 7 nights in Mauritius' tropical bliss from R13 215 per person sharing. Includes return flights, airport transfers and accommodation. Book now!

Kalahari.com - shop online today

Get many eggs in one basket!

Gaming bundles: 2 Super Hits games for R99, 3 Disney games for R99 and more + exclusive accessory bundles only available on kalahari.com. While stocks last. Shop now!

25% off bestselling books!

The Real Meal Revolution by Tim Noakes, Jeffrey Archer’s Be Careful What You Wish for, Man’s Search for Meaning by Victor E. Frank and many more titles. Shop now!

Up to 25% off electronics

Buy top electronics and save up to 25%. Such as kalahari.com’s 1# selling product the gobii eReader, Patriot X Porter flash drive, Asus Nexus 7” 3G tablet, Samsung Galaxy SIII, Lenovo G580 Notebook and many more. Shop now!

DStv HD PVR Decoder now R949

The DStv HD PVR Decoder has further revolutionised the television experience with lifelike viewing, sharper images, more vibrant colours and precision picture quality. Now R949, save R550. Offer valid while stocks last. Shop now!

Up to 30% off appliances & homeware

Save up to 30% on appliances and homeware this Easter! Offer valid while stocks last. Shop now.

OLX Free Classifieds [change area]

Samsung Galaxy s4

Mobile, Cell Phones in South Africa, Western Cape, Cape Town. Date October 24

Best bargain in big bay

Real Estate, Houses - Apartments for Sale in South Africa, Western Cape, Cape Town. Date October 25

VW Golf 6, 1.6 Trendline (Excellent condition)

Vehicles, Cars in South Africa, Western Cape, Cape Town. Date October 25

Nokia Lumia 800

The stunningly social Nokia Lumia 800 features head-turning design, ...

From R2395.00

I'm shopping for:

Horoscopes
Aquarius
Aquarius

You may find yourself fascinated by something which could draw you in to obsessively exploring this subject in depth....read more

There are new stories on the homepage. Click here to see them.
 
English
Afrikaans
isiZulu

Hello 

Create Profile

Creating your profile will enable you to submit photos and stories to get published on News24.


Please provide a username for your profile page:

This username must be unique, cannot be edited and will be used in the URL to your profile page across the entire 24.com network.

Settings

Location Settings

News24 allows you to edit the display of certain components based on a location. If you wish to personalise the page based on your preferences, please select a location for each component and click "Submit" in order for the changes to take affect.








Facebook Sign-In

Hi News addict,

Join the News24 Community to be involved in breaking the news.

Log in with Facebook to comment and personalise news, weather and listings.