Color Sense of Bees

Andrew Crone

Student Projects, Color

Introduction

Did you ever think that there is only one visible spectrum? Is the common rumor true that all animals are colorblind? Is it possible for bees to see one color when humans see a completely different color? A background on bees, scientific experiments, and diagrams will prove that bees have a unique color sense.

Background

Bees call their homes beehives and are social insects. There are around sixty thousand bees in an average beehive. One of these sixty thousand is a female, or the queen bee. The queen is the egg layer in the beehive. Another type of bee in the hive is the male, or drone. Drones are larger and plumper than the queen, and are, for the most part, stupid and lazy. The third type of bee in the hive is the worker bee. The worker bees are females except that they can lay no eggs because of undeveloped ovaries. Worker bees feed the larva and build the honeycomb. Only the worker bees leave the hive to gather food in forms of honey and pollenReplace these lines with your text

Scientists and Their Experiments

Professor C. von Hess, an ophthalmologist, in 1910, “performed many experiments on fishes, insects and other lower animals” (Frisch 4). His experiments were held in a “positively photo tactic condition – brightest available light” (Frisch 4). Hess used a spectrum to see what area the insects collected in. With the help of the spectrum Hess discovered that that the insects collected in the green and yellow-green part of the spectrum. Since the green and yellow-green part of the visible spectrum is the brightest part for a color blind human eye, Hess decided that that insects, and “in particular bees, are totally color blind” (Frisch 4).

Karl von Frisch, in 1915, not believing Hess’ conclusions, decided to test bees for a color sense. Frisch laid out on a table a blue piece of cardboard with honey to attract the bees to that color. After several times of bees returning to the blue piece of cardboard, Frisch removed the bees. He then put a blue piece of cardboard to left of the already placed blue cardboard and a red piece of cardboard to right of the already placed blue cardboard. Frisch then removed the original blue cardboard. This time he put no honey on either of the two new cardboards. If the bees saw blue “and remembered they found honey on blue they should fly to the blue cardboard” (Frisch 4). The bees did exactly that, and landed on the honey less blue cardboard. With this experiment Frisch can conclude that bees can distinguish between colors, but it still doesn’t determine whether or not bees have a color sense. Color Sense Explanation

Frisch decided upon a new experiment to find out if bees truly had a color sense. He placed a blue card on a table with different “gray cards of all shades from white to black” surrounding the blue card (Frisch 5). Frisch placed a small glass dish on each card, only adding food to the dish on the blue card. He would then switch the position of the blue card within the group of cards, still keeping the food only in the dish on the blue card. The bees continued to land on the blue card with the food. After some hours of this testing, Frisch took all the cards and dishes away and replaced them with new gray cards of all shades from white to black and a new blue card, and again a small glass dish on each card. The exception this time was there was no food in the dish on the blue card. “The bees remember the blue color and land only on the card, distinguishing it from all shades of gray. This means that bees have a true color sense” (Frisch 6).

Color Sense of Bees

The same experiment works with the single card of “orange, yellow, green, violet, and purple” but not with red (Frisch 6). With red, the bees are confused and land on the red card “but also on black and on all the dark gray cards” (Frisch 7). This experiment shows that bees are red-blind, they think red and black are the same color. Through the experiments of Frisch “it is clear that bees have a color sense, but that it is not quite the same as that of a natural human being” (Frisch 7). Although bees can distinguish colors from shades of gray, they have trouble distinguishing between colors. To the eye of a bee “orange, yellow, and green are the same color” – yellow. To the eye of the bee blue, violet, and purple are also seen as the same color - blue.

In 1927, Frisch’s experiments were expanded on by Professor A. Kuhn. Unlike Frisch, Kuhn used a spectrum instead of cards. Kuhn confirmed that bees see orange, yellow, and green as the same color as well as blue, violet, and purple as the same color. By using a spectrum Kuhn discovered two things that Frisch had overlooked. First, “there is a third quality of color in the narrow blue-green region (480-500 mu). Bees trained to blue-green can distinguish it from blue and from yellow” (Frisch 8). Second, he discovered a “fourth quality of color, ultraviolet (Explanation). It is a distinct color for the bees” (Frisch 8).

Comparison of Color Sense of Bees to Humans

The visible spectrum of a bee is shifted when compared to the visible spectrum of a human. The visible spectrum, for a human with normal vision, stretches from 800 mu to 400 mu. The visible spectrum, for a bee, stretches from 650 mu to 300 mu. This means that the visible spectrum for bees is shifted to shorter wavelengths. The visible spectrum is “shortened for the bees in the red, but it is extended into the ultraviolet,” a color that a human with normal vision can not see (Frisch 9). The major difference between the color sense of a bee and a human is that the “human eye can distinguish about sixty distinct colors in the visible spectrum, while the bee can distinguish only four different colors in the visible spectrum: yellow, blue-green, blue, and ultraviolet” (Explanation) (Frisch 9).

The combination of the shifting of the visible spectrum and the ability to see ultraviolet as a color enables bees to see a different color when the human eye sees one color (Explanation).

Conclusions

Bees have a unique color vision. Unlike humans, bees can only see four colors. One of the colors, ultraviolet, is unable to be seen by normal human vision. Bees have a completely different visible spectrum than a human's. Bees are red-blind. Because of a bee's visible spectrum, when a human sees a color a bee might see another color. Bees' vision is fun and interesting and very different from a human's.

Other References

Carl von Frisch. Bees: Their Vision, Chemical Senses, and Language.1963 Vail-Ballou Press, Inc. Cornell University Press, Ithaca, New York.

Carl von Frisch. The Dancing Bees. 1953 Harvest Book. Harcourt, Brace, and Co., New York.

Winston. The Biology of the Honey Bee. 1987 Harvard University Press. Camridge, Massachusetts and London, England.

Acknowledgements

Thanks JB, Will, and Sarah.