More proof that all species learn to adapt to their surroundings. A study has been released by the “Journal of Experimental Biology” that shows Arctic reindeer are able to see ultraviolet light, something humans are unable to do.  Ultraviolet light (UV) wavelengths are shorter than visible light, but longer than x-rays.  UV is actually named from the Latin term “ultra” which means beyond, or in this case, beyond violet.  Violet is the color of the shortest wavelength visible to the human eye. In fact, if the human eye is exposed to too much UV light, damage to the retina, cornea and lens is to be expected. Fortunately for us, most of the UV light is blocked by the earth’s atmosphere.  Everyone has heard of ozone right?

However, in the arctic, due to the vast amount of snow and the erratic day/night schedule, the small amount of ultraviolet light that does reach the earth is actually intensified due to scattering and reflecting off snow.

Being able to see UV light allows reindeer to see lichen, their main source of food, more clearly. The lichen appears darker to the reindeer, as do its predators. The arctic wolves are not able to blend in quite so easily with the snow for that sneak attack!

We already know that some creatures are able to see near ultra-violet light, such as bees and reptiles, but now the door is wide open to discovering more animals that can see actual UV light. It stands to reason that if arctic reindeer can see UV light, there is quite a good possibility that other arctic animals, such as seals and wolves, have learned to adapt to their environment and are seeing UV light as well. It’s a good thing for them since the ozone layer is being slowly depleted. Too bad for us humans though, as it will probably take a couple more thousand years of exposure to be able to adapt, since we aren’t truly indigenous to the arctic, but to the tropics. It takes a long time to adapt!

One interesting note, it was also recently <a href="http://www.wired.com/wiredscience/2010/03/arctic-reindeer-circadian-clock/"><span style="color: #008000;">discovered </span></a>that arctic reindeer do not use a circadian clock. It is actually switched off due to the irregular day and night schedules in the arctic. Reindeer need to graze every few hours, so a circadian clock would certainly throw a wrench in that idea! It is not known at this time what mechanism the reindeer use to know when to sleep and when to wake to forage for food.

Read a summary of the arctic reindeer ultraviolet light study <a href="http://jeb.biologists.org/content/214/12/2014.abstract"><span style="color: #008000;">here</span></a>.

Photo credit: flickr/timo_w2s