June 19, 2024

“Ascent” by electric jump – wissenschaft.de

Video: A nematode jumps on the hairy body of an electrically charged bumblebee. © Current Biology / Chiba et al.

You might think that worms can only crawl. But now a study shows that at least small nematodes are also capable of jumping: these research model animals seem to use electrostatic attraction forces in a targeted way to move through the air from A to B. For example, they can land on bees and then be transported through the air. It’s possible, the researchers say, that this electric method of ascent is also common among other small creatures.

It’s a science worm: the nematode Caenorhabditis elegans is used worldwide as a model organism in laboratories, especially in evolutionary biology and genetics. These worms, which reach a length of about one millimeter, live naturally in the soil and feed on the bacteria there. However, C. elegans can also be grown relatively easily in culture vessels for research purposes. Due to the extensive research that has been done on this small animal, a lot has already been known about its characteristics and behaviour. But now, a Japanese research team has revealed another exciting ability of the tiny creatures.

How do worms get to the cap?

As the scientists reported, the discovery began with an observation during typical work with test animals in the lab: They noticed that the worms they had cultured were often present on the lids of the Petri dishes corresponding to the culture medium. So the researchers wondered how they got there. To illustrate, they target the tiny creatures with video cameras. Through the recording, the scientists then discovered that the worms weren’t just crawling up the walls of the dish: They observed some nematodes jumping from the bottom of the dish onto the ceiling.

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Then the researchers conducted experiments to get to the bottom of this phenomenon in more detail. It soon became clear that the jumps were based on an electrostatic force: compared to the base, the lid of a petri dish could have enough electric charge to ensure an attractive force with the jumping effect. This is the effect that causes hair to stand on end, for example, when a friction-charged balloon approaches.

Through experiments with charged glass electrodes, the researchers were finally able to show more precisely how the worms react to differences in voltage. It becomes clear that this isn’t just a negative effect: the worms seem to straighten up when they feel an electrostatic force in order to be carried away. “The worms stand on their tails to reduce the surface energy between their bodies and the substrate, which makes it easier to attach themselves to objects,” says co-author Takuma Suji of Hiroshima University.

The hop on way to air travel

But why do they do that? As the team explains, the behavior can lead to the worms being disseminated “by the traveler”: C. elegans has been known to attach itself to snails in order to allow them to move around in an energy-efficient way. However, worms are also found on winged insects. Unlike snails, it wasn’t clear how the tiny creatures climbed onto these modes of transportation. The current discovery now offers a possible explanation for this. “Pollinators like insects and hummingbirds are known to be electrically charged,” says Suji.

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In order to see how far worms can actually use this ability to jump, he and his colleagues conducted experiments on bumblebees. To do this, they gave the insects electrostatic charges, which can also occur naturally, and used them to conduct experiments with C. elegans. It turned out that when the worms approached the bees and sensed the charge, they stood on their tails and finally jumped on board for a maximum distance of 2.4 mm. Some of the worms even piled on top of each other and then hopped onto the bees together in columns. The researchers concluded that it became clear that this phenomenon could have ecological significance for nematodes and possibly other small organisms as well.

Video: A close-knit group of worms takes off together. © Current Biology / Chiba et al

With further investigation, they now want to devote themselves to the question of what C. elegans’ “talent” for electric jumping is based on. It would help, according to them, to be a model organism: “There are well-established genetic methods for examining the relationship between behavior, neural activity, and genes,” the scientists wrote. According to the team, it may be possible to detect specific tendencies that play a role in electrostatic jumping behaviour.

Source: Cell Press, article: Current Biology, doi: 10.1016/j.cub.2023.05.042