Please select your home edition
Edition
Zhik ZKG

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

by Springer Science+Business Media/Sail-World on 20 Jan 2011
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
Protector - 660 x 82Wildwind 2016 660x82Zhik AkzoNobelb 660x82

Related Articles

America's Cup - Scary video from today's collision between GBR and JPN
LRBAR's hull not been stopped by SBTJ's windward foil there would have been serious injuries aboard the Japanese boat. All I can say is that had LRBAR's hull not been stopped by SBTJ's windward foil there would have been serious injuries aboard the Japanese boat. Moreover, notwithstanding the damage done to Land Rover BAR's boat, there must be considerable damage to the dagger-foil case of SBTJ. Considerable.
Posted today at 5:23 am
America's Cup - Day '1.5' gets underway in Bermuda
As Iain Murray put it so well, day '1.5' got underway in Bermuda today after postponement yesterday. As Iain Murray put it so well, day '1.5' got underway in Bermuda today after postponement yesterday.
Posted today at 4:08 am
A smashing start to the 35th America's Cup
Sir Ben Ainslie was forced to explain a highly dramatic collision in first day of Louis Vuitton America’s Cup Qualifiers Sir Ben Ainslie was forced to explain a highly dramatic collision in the first day of the Louis Vuitton America’s Cup Qualifiers on Bermuda’s Great Sound.
Posted today at 3:55 am
America's Cup - Day 1 - Dodgems continue on the Great Sound
The pre-start collision in Race 6 of the Qualifiers captured the click-bait attention but were otherwise a distraction The pre-start collision in Race 6 of the Qualifiers captured the click-bait attention but were otherwise a distraction to the real take-outs of the Opening day of the 35th America's Cup. First of these were the outcome of the rematch of the 2013 America's Cup protagonists - Oracle Team USA and Emirates Team New Zealand, in Race 5.
Posted today at 3:45 am
Two wins make Oracle Team USA form team on day one
Oracle Team USA was the only team to earn two wins from two starts on day one of the 35th America's Cup in Bermuda. Oracle Team USA was the only team to earn two wins from two starts on day one of the 35th America's Cup in Bermuda. On a picture-perfect Saturday afternoon skipper Jimmy Spithill as his team took a convincing win off Groupama Team France in the opener, before making a dramatic pass in the second race to beat Emirates Team New Zealand by just six-seconds.
Posted today at 3:37 am
America's Cup - Emirates Team New Zealand open with a win
Emirates Team New Zealand kicked off their 35th America’s Cup campaign with a convincing win over Groupama Team France Emirates Team New Zealand kicked off their 35th America’s Cup campaign with a convincing win over Groupama Team France on Bermuda’s Great Sound today. It was the first race for the new look kiwi team racing on sailings greatest stage, and managed to beat the French team with the composure expected of America’s Cup veterans.
Posted on 27 May
Oracle Team USA opens 35th America's Cup with a convincing win
Oracle Team USA opened its quest for a three-peat with a win over Groupama Team France on Saturday afternoon in Bermuda. In picture perfect conditions, skipper Jimmy Spithill won the first start of the Louis Vuitton America's Cup Qualifiers with a timed run to the starting line.
Posted on 27 May
America's Cup - Grudge Match of 2013 Final on Day 1 in Bermuda
The 35th America's Cup will get underway a day late, but in excellent weather that was worth the wait. The 35th America's Cup will get underway a day late, but in excellent weather that was worth the wait. There will be plenty of interest in the key race of the day - Race 5 where Emirates Team New Zealand comes up against Oracle Team USA in a replay of the 2013 America's Cup Match
Posted on 27 May
America's Cup - Adventures of a Sailor Girl in Bermuda!
Wow! Who would have thought that we would have to wait even longer for the start of the America's Cup events Wow! Who would have thought that we would have to wait even longer for the start of the America's Cup events when arriving here this week! I wonder who bet on a late start for all of the teams, when racing was officially postponed on the evening of the Louis Vuitton America's Cup Qualifier Series here last night!
Posted on 27 May
America's Cup - Emirates Team New Zealand is ready to race - Video
It's nearly time to race... The first race of the Louis Vuitton America's Cup qualifiers is scheduled for May 27. It's nearly time to race... The first race of the Louis Vuitton America's Cup qualifiers is scheduled for May 27. Emirates Team New Zealand Skipper Glenn Ashby: 'I am 100% confident we have the right men for the job'
Posted on 27 May