Plants That Move
Susanne Menden-Deuer and Elizabeth Harvey were watching a variety of plant as an animal approached that fed on that sort of vegetation. The plant then did something that surprised the two women a great deal: the plant physically moved itself away from the predatory threat. True, the plant is just a microscopic dot called phytoplankton and the animal in question was a similarly sized specimen of zooplankton but the fact that a plant could recognize a threat and use strategies to avoid it, showed a complexity entirely unexpected.
Menden-Deuer is an associate professor, while Harvey is a doctoral student; both with the University of Rhode Island’s Graduate School of Oceanography. The two had been monitoring interactions between phytoplankton and zooplankton when they made their discovery.
“It has been well observed that phytoplankton can control their movements in the water and move toward light and nutrients," Menden-Deuer was quoted in a recent eScience report. "What hasn't been known is that they respond to predators by swimming away from them. We don't know of any other plants that do this."
The two scientists observed, when they took their findings back to their lab, that this species of phytoplankton, known as Heterosigma akashiwo, would drift in a different direction than where the predator appeared to be headed, even seeking out areas of low salinity that would be harmful to the predator. They do not exhibit this behavior in the presence of predators that don’t consider this species of phytoplankton as prey.
"The phytoplankton can clearly sense the predator is there. They flee even from the chemical scent of the predator but are most agitated when sensing a feeding predator," Menden-Deuer stated
She went on to describe how their research could be a benefit to the larger scientific picture.
"One of the puzzling things about some phytoplankton blooms is that they suddenly appear," she said. "Growth and nutrient availability don't always explain the formation of blooms. Our observation of algal fleeing from predators is another mechanism for how blooms could form. Amazingly, looking at individual microscopic behaviors can help to explain a macroscopic phenomenon."
Hopefully, using genetic modification, we won’t end up with a lawn we have to chase with the mower.
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