Hollyhock in Ulta Violet light

Beauty is in the eye of the beholder

All UV images are by Craig Burrows

Karl von Frisch (November 20, 1886 – June 12, 1982) was a very clever man who received the Nobel Prize in 1973 for his work in the field of animal social behaviour. I suppose he is best known for the discovery of the “waggle dance” by bees, which deserves a blog post of its very own, but today I’m going to be writing about how bees and many other insects perceive colour.

Von Frisch conducted experiments whereby he fed bees sugar syrup in a tray placed on a coloured card. Over time the bees visited the food on the coloured card, and when he later placed the coloured card in an array of grey cards, he could test whether or not the bees could “see” that colour. For example, if they were accustomed to getting their sweet treat from a tray on a blue card, and then that blue card was surrounded by grey cards, would they go straight to the blue card or try out the grey ones? In this way Von Frisch found out that bees can see colours, and after much experimentation he realised that their perception of colour is different to ours. Bees are not sensitive to the colour red (to them it looks black) but they are sensitive to ultra violet light, which is invisible to us. He later went on to show that they have a similar sense of smell to humans but a much less sophisticated sense of taste.

In the early days Von Frisch was quite controversial. He was a firm believer in Darwinian evolution and thought that in order to survive over millennia animal species had to adapt their senses to work better in their environments. It seemed reasonable that flowers were brightly coloured in order to attract pollinators, and for that to be true the pollinators would have to be able to see colours, so he tested this out and proved it to be the case. Many traditional scientists of the time believed that animals saw in black and white, and that fish could not hear. Von Frisch showed that bees see colours and that fish can hear. As a walrus I have always known that fish can hear, which is why I have had to develop stealth and guile in order to hunt them, but I digress…

Cute walruses
Keep it quiet, they can hear us!

Clearly bees do not see the world in the same way that humans do, one difference being their sensitivity to light of shorter wavelengths. I have recently been looking at some of the photography of Craig Burrows who is based in Southern California and who has photographed flowers in dark rooms in the presence of UV light. The images are very beautiful and show that the markings on the flowers are directing bees and other pollinators towards the important area of the flower. For bees this is where the nectar and pollen is, because bees, which are vegetarian, get their carbohydrate from nectar and protein from pollen. To the plant the pollinator is carrying out their reproduction for them so it is to their advantage to have the amazing displays of light and colour that we see in Craig’s images.

Mexican Sunflower in Visible (left) and UV (right) light
Mexican Sunflower in Visible (left) and UV (right) light
Hawthorne in UV light
Hawthorne in UV light

An idea of what a human face looks like to a bee is shown below (wear sunscreen, folks!):

Human Face Visible (left) and UV (right)
Visible (left) and UV (right)

In his “A Biologist Remembers” (1967) Von Frisch wrote about his life’s work:

“The layman may wonder why a biologist is content to devote 50 years of his life to the study of bees and minnows without ever branching out into research on, say, elephants, or at any rate the lice of elephants or the fleas of moles. The answer to any such question must be that every single species of the animal kingdom challenges us with all, or nearly all, the mysteries of life.”

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