Have you ever wondered what the natural world of meadows, flowers, grass and trees must look like seen through the faceted compound eyes of a honey bee or a bumblebee? Do they see in color?
How many eyes do you think a bee has? Two you say? No, actually, bees have five eyes in all. No, this isn't a trick question. On top of their head are three simple eyes, known as ocelli, arranged in a triangular pattern. These simple eyes with a single lens are best for informing the bee of changes in light intensity. These ocelli help them navigate around flowers and getting to and from the nest at dawn and dusk.
The color sense of honey bees (and other bees) was only guessed about until this century. Biologists since C.K. Sprengel (1793) had long believed that flowers acquired their colors as "living billboards" to advertise their presence to passerby insects who would, in turn, move their pollen grains from flower to flower--resulting in fruit and seed set for the flowering plants. Sprengel even called the markings on some colorful flowers "saftmale" (in German), sap signs in English to note that they were landing and orientation guides for flower-visiting insects. By being colorful, they thought, it would be easier for floral insect visitors to see the small flowers set against the green or brown backdrop of most environments. If bees and other insects could see and find them easily, that would allow them to move amongst the blossoms faster thus increasing their efficiency as pollinators.
In fact, honey bees were thought to be color blind until the pioneering experimental research of the late Dr. Karl von Frisch in Germany during the the early part of this century. He proved that they do in fact have three color (trichromatic) vision in many respects like our own visual system. Karl von Frisch was able to demonstrate that bees had color vision by training them to a little dish of scented sugar water (their sweet reward) set upon a blue square of paper. By randomly placing this blue square in a big "checker board" of gray squares, he could tell that the bees actually saw and recognized/learned where the blue square was positioned. They weren't just relying upon the relative intensity of the squares. This training technique has become the standard for many bee behavioral experiments up to the present day.
Although both honey bees and people have a visual system based upon three-colors, the limits of this color sensitivity are very different. People cannot see very far into the Violet or Ultraviolet region of the electromagnetic visual spectrum. We are essentially blind to wavelengths of light below 400 nanometers/millimicrons (light in this regions is called UV-A and UV-B light). These are the powerful light rays which cause us to tan or sunburn. Bees can see these invisible-to-us rays of light! Another interesting difference happens at the opposite end of the visible spectrum. We can easily see the color of a red sweater or red fire engine (at least many of them used to be red!). To a honey bee, however, the color red is invisible. They see red objects as black, or the absence of color. Share this with your friends at school, your teachers and parents. Did they know that bees are not colorblind and that they can see "secret" colors that we cannot?
In the photograph above we see an array of flowers as they appear to people who might be admiring them in a display case within a florist shop. Notice that they occur in many different shapes and sizes with various subtle color markings on their petals. The colors of flowers are said by physicists to be highly saturated. That makes them very noticeable when compared to other less-saturated colored objects in the natural environment. *These magnificient photographs appeary courtesy of Dr. Randolf Menzel (Berlin, Germany).
The collection of photographs below show what the same flowers would look like to a passing honey bee. Notice that the photos are dark blue/black. These were taken by using a special ultraviolet-transmitting filter described below. Although we don't really know exactly how the bees eyes see the patterns (and their brains interpret these neurosignals) we do know that these hidden UV colors do stimulate the bees vision and tell them where to find the floral rewards (nectar and pollen) inside the flowers.
picture: not done
Humans can see wavelengths from around 400 (blue) to as far as 800 (red) nanometres, whereas bumblebees can see from as low as 300 (ultra violet) but only up as far as 700 (orange) nanometres. The three basic colours seen by humans are red, green and blue, and by bumblebees they are green, blue and ultra violet. Bumblebees cannot see red, but they do visit red flowers. This is because as well as being able to smell the nectar and any other attractive odour that the flower may emit, many flowers, not only those we see as red, have ultra violet patterns on the petals that are visible to bumblebees and some other insects, but invisible to us.
Well........... I hope it will help you to understand more.
reference:
http://gears.tucson.ars.ag.gov/ic/vision/bee-vision.html
http://www.bumblebee.org/bodyEyehtm.htm
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