Tiny Plants Like Microalgae Sense Predators and Swim Away

Phytoplankton can move away from predators similar to animals, finds a new study.

They are similar to plants which require sunlight to grow. Just like terrestrial plants, microalgae phytoplankton indulges in photosynthesis process to turn the light from sunlight into chemical energy. They live in both saline and fresh water, and release oxygen after consuming carbon dioxide.

A team of researchers led by principal investigator Susanne Menden-Deuer, of the University of Rhode Island, observed the movements of a type of phytoplankton known as Heterosigma akashiwo when facing their predator - the zooplankton - in order to understand the behavior of the algae when they are attacked.

They performed a series of lab experiments and found that the plant-like microorganisms either fled their place or moved their distribution to another location whenever they encountered a predator.

In fact, experts were surprised to notice that the microalgae moved away from the spots where the zooplankton were previously located long even after they were gone.

"The phytoplankton can clearly sense the predator is there," LiveScience quoted Menden-Deuer as saying.

"They flee even from the chemical scent of the predator but are most agitated when sensing a feeding predator," she said.

While it is already known that phytoplankton move in the direction of light so as to get the required nutrients, this is the first time that the tiny plants have been observed in such an escaping behavior from the hands of the dreaded predator.

When the experts measured the survival rate of the plants, they found that the predators were able to feed on the algae in a single day if the algae did not have any refuge. However, when the researchers offered low saline water as refuge for the tiny plants which the predators cannot stand, phytoplankton took refuge and their population growth increased once in every two days, the LiveScience report said.

It is not known whether the behavior is common among all species of phytoplankton. "If it is common among phytoplankton, then it would be a very important process," Menden-Deuer said.

Menden-Deuer and her colleagues are further planning to analyze the genetics of phytoplankton's predator avoidance behavior in oceans.

The findings of the study are published in the journal PLOS ONE.