The day I asked my dad if he sees the same shade of green that I do when looking at the grass, and he answered we can’t ever know, sparked my lifelong fascination with perspective – the unique way each person and lifeform experiences this world we share. There’s a word for it, umwelt, which refers to the perceptual experiences of each life form. In other words, no matter how much I tell you about me, or you tell me about you, we can never really know what it’s like to be each other. You can’t know what it’s like to have my thoughts, memories, or feelings, and I can’t know yours any more than I can know for certain how my cats experience life, or my plants.
Still, there is much we can learn about each other and other life forms. It’s easy for you and me to learn about each other through observations and conversation, but learning about how plants or other animals experience life is a little more tricky. Especially since, while we may view our species as superior to all the rest, other animals have remarkable abilities that we don’t possess. For instance, humans use our bodies and verbal language to communicate, but some life forms use other methods to exchange information. For instance, bees don’t just randomly choose which flowers to visit, flowers tell them when they’re full or empty of pollen, and when they’re occupied with another visitor by using electric fields.
Following a Curiosity
Scientists first began theorizing that natural electric forces enhance the relationship between pollen and pollinators, such as bees, since the mid-1970s and early 80s. However, The idea couldn’t progress beyond that at the time because the technology wasn’t advanced enough to test it. As a result, the theory fell to the wayside until resurfacing again in 1995 and 2001, with the first empirical evidence supporting the idea. Even still, more research was needed.
Then, around 2013, sensory biologist and Professor of Bionanoscience at the University of Bristol, Daniel Robert, stumbled upon the concept and came at it from a different perspective. Many of the scientists researching how slight electrical charges of a flower or pollinators affect the pollination process were botanists, but as a sensory biologist, Robert studies how animals perceive, or sense, the world around them. So, when he came across this under-researched relationship, the question that first popped into his mind, he told National Geographic was:
“Does the bee know anything about this process?”
Incredibly, it appeared no one else wondered, much less investigated or found an answer. Robert told National Geographic:
“We read all of the papers. We even had one translated from Russian, but no one had made that intellectual leap.”
Rather than drop his curiosity, Robert teamed up with physicist Dominic Clarke, biologist Gregory Sutton, and botanist Heather Whitney to follow his curiosity and find answers -- and this is precisely what they did. They published their research in the journal Science in February 2013, along with further research published in June 2017 in the Journal of Comparative Physiology.
How it Works
In short, the team discovered that bumblebees can sense a flower’s electrical field, distinguish between fields formed by different floral shapes, and tell whether another bee recently visited a flower.
See, both flowers and bees have electrical fields. As they fly, bees bump into charged particles, such as dust and other small molecules. The friction of these tiny collisions knocks electrons off the bee’s surface, leaving them with a positive charge.
Meanwhile, flowers usually have a negative charge, particularly during mild weather. A plant’s roots in the ground give it a slight negative electric charge. The higher the plant grows, the higher the electric charge it has because the air around the plant also has an electric charge that increases every meter above the ground. This creates a faint electric field around the plant.
Now for the fun part.
One interesting observation is that pollen will hop from the flower to the bee when a positively charged bee approaches the negatively charged flower. Robert told National Geographic:
“We found some videos showing that pollen literally jumps from the flower to the bee, as the bee approaches… even before it has landed.”
Further, the positively charged bees slightly increase the charge of any flower they land on beginning just before landing and lasts for just shy of two minutes – much longer than a bee usually spends visiting a flower. The team demonstrated that when a bee lands on the stem of a petunia, its electrical potential increases by approximately 25 millivolts.
Bees sense this slight change in a flower’s electrical field, which communicates that the flower has recently been visited and is likely low on nectar. It’s sort of like the flower is telling the bee, “I’m out of stock. Check back later.” Meanwhile, when a bee makes contact with a flower, it cancels out the single – which tells other bees, “I’m occupied.”
No one knows for sure how bees actually sense electrical fields. But Robert and others believe the electric fields affect part of a bee, like its antennas or the tiny hairs on its body. Similar to how rubbing a balloon on your head makes your hair stand up. Another possibility is that bees sense the field through a feeling, such as a slight pull or tug toward flowers that increase depending on how charged a flower is.
Since Then
While scientists haven’t yet figured out exactly how the interaction between bees and flowers in electric fields works, they have found that bees are not unique in this capability. As far back as 1962, scientists have suspected that insect cuticle material – the armor-like exoskeleton many insects have around their body – is prone to acquiring an electric charge.
One potential example of this occurring in a non-pollinator comes from 2018 when a sensory ecologist teamed up with Robert and discovered spiders use Earth’s electrical field in a surprising way. Believe it or not, spiders are known to cross oceans. For a long time, it was assumed that spiders make the journey by riding the wind, but Morley and Robert found that, while the wind may be one factor, spiders also ride the planet’s electrical field across. They published their findings in the journal Current Biology.
Going back to the interaction between flowers and bees for a moment, one thing researchers, including Robert, hope to learn more about in the future is how this exchange occurs in places like rainforests. Robert’s 2017 study, explains that environmental factors can affect electric fields. They write:
“High humidity, for example, leads to the formation of moist films on surfaces which prevent charge build up, and a dense rainforest canopy acts like a Faraday cage, negating the influence of the atmospheric electric field at ground level, possibly preventing the formation of floral electric fields altogether.”
So, in the future, they’d like to learn how various environmental conditions affect the electrical field of plants and influence the foraging behavior of pollinators.
Of course, electric fields are everywhere on Earth, and insects are just one of a growing list of species that are sensitive to them. Countless animals can detect electrical fields and use them to do everything from hunting to traveling and communicating. As research continues, we’ll undoubtedly discover even more.
Perspective Shift
One of the best things about this knowledge is that you don’t have to travel or book a vacation to see it. From now on, you’ll know the miraculous interaction happens anytime you see a bee and flower interacting. You can watch the interaction and know there is an exchange between these two vastly different species, one we humans can only observe and not experience.
Not only does this knowledge make previous mundane observations more magical, but it’s also a humbling reminder that as brilliant as the human species can be, other animals experience the world wholly differently than we do and are capable of doing things we may never fully understand.
By the way, I got the idea for this article from a fascinating Instagram post that went viral demonstrating the interaction between a bee and a flower’s electrical charges using sound.
