The latest from Dale Wood, Apiary Man, on bee vision.
What does a bee ‘see’ as it buzzes around its world?
Every now and then an article catches my eye (please pardon the pun) and this latest one was about ‘bee vision’.
Did you know, bees have a 300° field of vision, give or take a little. For humans it’s around 180°.
Karl von Frisch constructed experiments in the 1920’s that established that bees can not only see colour, but that they can distinguish between different colours (and that they cannot ‘see’ red).
Did you know, there are more creatures with compound eyes than any other form of eye?
A compound eye is made up of thousands of ‘ommatidia’. Individual facets arranged on a convex surface, all pointing in slightly different directions. Each ommatidia has its own optic nerve connecting it to the bees brain so it sees a pixelated image.
This curved arrangement of flat plates is especially good for detecting subtle movement. The facets capture any slight movement in a bee’s environment and send a warning message to the brain.
Did you know, a queen honey bee has around 4000 ommatidia, a worker has 6900 and a drone has 8600. A drone’s main purpose in life is to mate so it has to be able to locate a virgin queen quickly and accurately. Better eyesight is essential.
Did you know, both humans and bees have trichromatic vision?
As humans, the wavelengths of light visible to us ranges from 380 to 750 nanometers, basically, the colours of the rainbow. Shorter wavelengths, 380-450nm, give us violet and the longer wavelengths, 625-750nm, give us red.
Trichromacy is when the retina contains three types of colour receptors or cone cells.
We have colour receptors in our eyes that are most sensitive to three main wavelengths of light. Those at around 450, 550 and 650nm giving us blue, green and red (have you fiddled with the colour balance on your TV? If so, you’ve been altering the intensity of blue, green and red).
Bees on the other hand, have colour receptors that are mostly sensitive to wavelengths of around 350, 450 and 550nm or ultra-violet, blue and green.
The ability to be able to see ultra-violet light means that bees can continue to use the sun as an aid in navigation even when the sun is obscured by cloud. Ultra-violet light penetrates cloud.
Also, the evolution of bees and flowers occurred, more or less, side by side from about 150 million years ago and flowers have what are known as ‘nectar guides’ which, as the name suggests, direct the bee towards where the reward is. These guides are visible in ultra-violet light but are not visible to our eyes.
Did you know, bee’s eyes have a flicker rate 5 times that of humans.
Laboratory experiments have shown that honey bees can discern black and white stripes at 300 stripes per second. By contrast, humans can only detect 15–20 stripes per second before the images blend together. If you were to share your old 16mm home movies with a bee, the bee would soon get very bored with the series of still pictures it was seeing.
‘What’s that?’ said the honey bee.
‘Is that a rolled up newspaper heading towards me?’ she pondered, as she yawned, again.
...still the newspaper crept closer...
‘Oh well, maybe I should move out of its way’, she mused whilst giving her antennae another clean.
‘These humans are so very slow’, she thought to herself as she casually flew off to seek her next flower.
Apiary man (Dale Wood)
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