Scientists Recreate the Mysterious Feeding Habits of This Bizarre 550 Million-Year-Old Organism

Between 570 and 540 million years ago, a group of bizarre, soft-bodied creatures known as Ediacaran organisms emerged in Earth's oceans, representing the first major group of complex, multicellular life on the planet.

A team of scientists has reconstructed how one of these early organisms fed for a study published in the journal Science Advances, lending weight to the hypothesis that many of this group behaved more like modern animals.

Ediacaran organisms represent an important milestone in the evolution of life on Earth as they immediately precede the so-called Cambrian Explosion—a rapid increase in biodiversity when most of the major animal groups appear in the fossil record.

But it is unclear how the Ediacaran biota—as they are referred to—relate to modern animals, because they largely disappeared right around the time when the Cambrian animals really took over the ocean floor.

As such, the placement of Ediacaran organisms on the tree of life is contentious. Some are most probably true animals. But many of the larger examples are quite distinct from later life-forms: Among them are large, flat quilt-like creatures; tube-shaped organisms; and plant-like, leaf-shaped critters.

"The Ediacaran biota includes fossils of some of the oldest large and complex lifeforms known," Jennifer Hoyal Cuthill, a paleobiologist from the University of Cambridge and the Tokyo Institute of Technology who was not involved in the latest study, told Newsweek.

"These early fossils are not quite like anything alive today. So there has been considerable scientific debate on where they belong in the tree of life," she added. "While it had been suggested that at least some of the large, complex fossils might have been early animals, almost every other possibility has also had its advocates: from seaweeds to giant protozoans."

In the latest study, researchers analyzed fossils found in the African nation of Namibia to reconstruct—with the help of computer simulations—the feeding habits of one Ediacaran organism known as Ernietta—a sack-like, tube-shaped creature.

"This study stemmed from the fossils that we were finding in the southern area of Namibia, where we do fieldwork," Brandt Gibson, lead author of the study from Vanderbilt University, told Newsweek. "We were finding places where we could count large numbers of these fossils, and we were even finding rock surfaces where we had good evidence for them still being in life position."

"That led to two questions: One, what are they doing there? And two, why are we finding them living together? Answering these types of questions ultimately informs our understanding of what early life and more primitive ecosystems were like leading up to animals taking over the ocean floor," he said.

The authors of the study simulated the flow of water into the Ernietta fossils to understand how the creature could have fed. These simulations revealed that these organisms acted like suspension feeders, which trap nutrients in deep cavities.

Furthermore, the models indicated that by working together, the creatures may have been able to adjust their bodies in such a way as to manipulate the water flows around them, thus increasing the amount of food they received.

"The results of this study are particularly interesting because they show that these organisms are likely benefiting from living in groups by aiding each other in feeding," Gibson said.

"That type of behavioral interaction is something we see today in mussels and other organisms, but this is one of the oldest examples of it that we currently have found in the fossil record—and at the same time as the early animal fossil record," he said. "It shows us that these enigmatic organisms are likely more similar in behavior to animal organisms than we originally thought."

Ernietta, Ediacaran organism
Artistic reconstruction of a gregarious community of Ernietta. Dave Mazierski