New insights into the mysterious sixth sense.
Bumblebees look fuzzy because their bodies are covered in tiny hairs. Though the hairs are known to act as insulation and to help the bees transport pollen, a new study reveals that they are also the key to the bumblebee’s rare ability to detect electric fields.
Because water conducts electricity, numerous aquatic animals are capable of sensing electric fields. The list includes sharks, rays, amphibians, ray-finned fish, and dolphins. Even land-dwelling spiny anteaters have electric sense organs, but they only function when they are submerged in water.
Bumblebees, on the other hand, are surrounded by air — a medium through which electric currents struggle to travel. Yet, bumblebees display sensitivity to the electric fields surrounding flowers and those created by other bees when they perform their signature waggle dance.
So how do bumblebees actually perceive these electric fields?
A team of researchers posited that the fields might exert a small force that moves structures on the bee’s body, perhaps their antennae or body hairs.
Using a precise instrument called a laser vibrometer to measure the movement of hairs and antennae, the researchers found that both structures deflect in response to an electric field, but the hairs moved with greater intensity and speed. They also found that hair movements triggered neural activity in the bees, whereas there was no neural response when the antennae deflected.
“Arthropod [a group that includes insects and spiders] hairs have previously been shown to react to extremely large electric fields — the kinds generated by a power cable,” study lead author Gregory Sutton from the University of Bristol’s School of Biological Sciences told The Science Explorer. “This is the first time hairs have been shown to react to the small electric fields found in nature.”
The researchers published their findings in the journal PNAS.
While detection of electric fields surrounding flowers and other waggle-dancing bees may be all that bumblebees care about, this ability could serve a variety of functions in other arthropod species
“This electroreceptive mechanism measures small forces at a distance of approximately 10 cm away or so,” Sutton explains. “There are a huge number of things arthropods may want to know about in that size range; the most obvious of which is other arthropods. This sense may possibly be used to detect predators or prey.”
However, just how widespread this phenomenon is in the arthropod world is currently unknown. “The next step is to determine whether this kind of sense is present in other insects, or if bees are somehow 'special' in that only they detect electric fields,” said Sutton, noting that either finding would be very interesting.
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