News Home Video Gallery Newsletters Cruising Int Photo Gallery

 

Sail-World.com : Are sharks colour blind? Why NOT to wear black swim gear

Are sharks colour blind? Why NOT to wear black swim gear

'Are sharks color blind?'    DPI Victoria
Sharks are unable to distinguish colors, even though their close relatives rays and chimaeras have some colour vision, according to new research by Dr. Nathan Scott Hart and colleagues from the University of Western Australia and the University of Queensland in Australia. And this leads to the question -when you dive off your sailing boat to cool off or go snorkelling, should you be wearing pale blue swimmers and wetsuits?

Their study shows that although the eyes of sharks function over a wide range of light levels, they only have a single long-wavelength-sensitive cone* type in the retina and therefore are potentially totally color blind. Hart and team's findings are published online in Springer's journal Naturwissenschaften – The Science of Nature.

'This new research on how sharks see may help to prevent attacks on humans and assist in the development of fishing gear that may reduce shark bycatch in long-line fisheries. Our study shows that contrast against the background, rather than colour per se, may be more important for object detection by sharks. This may help us to design long-line fishing lures that are less attractive to sharks as well as to design swimming attire and surf craft that have a lower visual contrast to sharks and, therefore, are less ‘attractive’ to them,' said Prof. Hart. While it is probably safer to swim in the same waters as a shark than it is to drive a car, the news is food for thought for all prudent sailors, many of whom spend a considerable amount of time off their yachts in water sports, sometimes in shark-infested seas.

Sharks are efficient predators and their evolutionary success is thought to be due in part to an impressive range of sensory systems, including vision. To date, it is unclear whether sharks have color vision, despite well-developed eyes and a large sensory brain area dedicated to the processing of visual information. In an attempt to demonstrate whether or not sharks have color vision, Hart and colleagues used a different technique - microspectrophotometry - to identify cone visual pigments in shark retinas and measure their spectral absorbance.

They looked at the retinas of 17 shark species caught in a variety of waters in both Queensland and Western Australia. Rod cells were the most common type of photoreceptor in all species. In ten of the 17 species, no cone cells were observed. However, cones were found in the retinae of 7 species of shark from three different families and in each case only a single type of long-wavelength-sensitive cone photoreceptor was present. Hart and team's results provide strong evidence that sharks possess only a single cone type, suggesting that sharks may be cone monochromats, and therefore potentially totally color blind.

The authors conclude: 'While cone monochromacy on land is rare, it may be a common strategy in the marine environment. Many aquatic mammals - whales, dolphins and seals - also possess only a single, green-sensitive cone type. It appears that both sharks and marine mammals may have arrived at the same visual design by convergent evolution, in other words, they acquired the same biological trait in unrelated lineages.'

*There are two main types of photoreceptor cells in the retina of the eye. Rod cells are very sensitive to light and allow night vision. Cone cells also react to light but are less sensitive to it. Eyes with different spectral types of cone cells can distinguish different colors. Rod cells cannot tell colors apart.

ReferenceHart NS et al (2011). Microspectrophotometric evidence for cone monochromacy in sharks. Naturwissenschaften – The Science of Nature; DOI 10.1007/s00114-010-0758-8




by Springer Science+Business Media/Sail-World

  

Click on the FB Like link to post this story to your FB wall

http://www.sail-world.com/index.cfm?nid=79375

6:28 AM Thu 20 Jan 2011 GMT






Click here for printer friendly version
Click here to send us feedback or comments about this story.


Cruising USA









Springtime Greening: Boaters Tips for Earth Day by BoatUS Foundation/Sail-World Cruising,








How sailors really do have a voice in the future of our oceans by Sandra Whitehouse, Sailors for the Sea,


Message-in-a-bottle record - 102 years by AFP/Sail-World Cruising,








Canadian solo sailor rescued north of Auckland by Sail-World Cruising round-up,




















Free online fuel spill course - how much do you know? by BoatUS Foundation/Sail-World Cruising,












Life-shattering event sends 'rookie' couple sailing the world by Asia News Network/Sail-World Cruising,








3,200-year-old boat found in Croatian waters
Product of the Week: the LineGrabber
Mediterranean Mooring - How to moor stern-to to a dock or quay
Canadian storm bomb threat - sailors advised: get off the water!
Sailing family condemmed for taking 3-year-old on circumnavigation
New contract-free plan for satellite communicator on your smart phone
Yacht of the Week: The Dashew creation: no sails, but eco-friendly
No laughing! Sailing mistakes I don't want to make
Destination: From Moscow Sea to the White Sea
Land sailors of India on adventure across the Rann
A Paint App to (almost) replace your marine store assistant
Volunteer Canadian rescue team homeless - any offers?
Hilary Lister and Nashwa Al Kindi set a new trans-ocean record
How to anchor and 'never utter a word'
Non-pyrotechnic flares for my boat - Can I or can't I?
Health benefits of sailing
Cruising in the Maldives - some nuts and bolts
ISAF Guide to Offshore Personal Safety for Racing and Cruising
Halyard Tension - a video
Winchrite - for lazy days or extra muscle-power
Researcher examines 'current leaks' that may change the way you sail   
Paris off to attempt to circumnavigate the world again   
Need a tow from that helicopter? - watch the video and don't laugh   
Certain oil spill products shown to be ineffective and toxic + Video   
The Constrictor: a powerful 'Queen' of sailing knots!   
Boat painting - simple but best tips   
'It's never just one thing' - Swedish sailors rescued   
Cruising Club of America celebrates outstanding sailors of 2013   
Book of the Week: From the Galley of...   
Two brave women to sail India to Oman across Arabian Sea   
Rhode Island's Classic Yacht Symposium - Registration opens   
Bad Karma as roving American cruising sailor fined in New Zealand   
Another rescue for second-time unlucky solo sailor   
New York to San Fran record attempt - Maserati reaches the Horn   
Finally the book:HMS Bounty, Disaster and Survival in Superstorm Sandy   
Yachts impounded in Mexico - the agony goes on...   
Students achieve robot boat Atlantic Crossing - but not as planned   
Endurance Award for cruising sailors, new worldwide award for 2014   
It's coming. Dodgers/biminis to be solar power producers   
New Maldives rule - yachts can stay six months   


For this week's complete news stories select    Last 7 Days
   Search All News
For last month's complete news stories select    Last 30 Days
   Archive News







Sail-World.com  


















Switch Default Region to:

Social Media

Asia

Australia

Canada

Europe

New Zealand

United Kingdom


http://www.sail-world.com/event_images/image/Twitter_logo_small.png http://www.sail-world.com/event_images/image/FaceBook-icon.png  

United States

Cruising Northern

Cruising Southern

MarineBusiness World

PowerBoat World

FishingBoating World

 

Contact

Commercial

News

Search

Contact Us

Advertisers Information

Submit news/events

Search Stories/Text

Feedback

Advertisers Directory

Newsletter Archive

Photo Gallery

 

Banner Advertising Details

Newsletter Subscribe

Video Gallery

Policies

 

 

 

Privacy Policy

 

 


Cookie Policy

 

 



This site and its contents are © Copyright TetraMedia and/or the original author, photographer etc. All Rights Reserved.  Photographs are copyright by law.  If you wish to use or buy a photograph contact the photographer directly.
X6XL NEW Cru USA