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Establishment of Microbial Eukaryotic Enrichment Cultures from a Chemically Stratified Antarctic Lake and Assessment of Carbon Fixation Potential
Published on: April 20, 2012
From the Cover: Osmotrophy in modular Ediacara organisms
Marc Laflamme1, Shuhai Xiao, Michał Kowalewski
1Department of Geosciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
Summary
Ediacara biota, like rangeomorphs and erniettomorphs, may have used osmotrophy for feeding. Their fractal structures provided high surface-area-to-volume ratios, enabling nutrient absorption similar to bacteria.
Area of Science:
- Paleontology
- Evolutionary Biology
- Biophysics
Background:
- The Ediacara biota are early complex life forms with debated feeding strategies.
- Rangeomorphs and erniettomorphs, key Ediacaran organisms, lack oral openings, challenging macrophagus feeding hypotheses.
- Photoautotrophy is unlikely for rangeomorphs due to their deep-water habitats.
Purpose of the Study:
- To evaluate osmotrophy as a primary feeding strategy for Ediacaran rangeomorphs and erniettomorphs.
- To determine if their morphology supported the high surface-area-to-volume ratios required for osmotrophy.
- To understand the ecological role of these early macroorganisms in nutrient cycling.
Main Methods:
- Theoretical modeling of surface-area-to-volume ratios.
- Analysis of empirical data on Ediacaran organism morphology.
- Comparison of calculated ratios with those of modern osmotrophic bacteria.
Main Results:
- Fractal branching in rangeomorphs yielded high surface-area-to-volume ratios, comparable to osmotrophic bacteria.
- Erniettomorphs could achieve bacterial-level osmotrophic ratios with metabolically inert materials.
- Morphological adaptations likely facilitated osmotrophy in these macroscopic organisms.
Conclusions:
- Osmotrophic feeding is a viable strategy for Ediacaran rangeomorphs and erniettomorphs.
- Specific Ediacaran morphologies may have overcome physiological limits for osmotrophy.
- These early macroorganisms potentially played a significant role in cycling dissolved organic carbon during the Ediacaran period.
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