Soil protists — the invisible engines of ecosystems

Exploring protists feeding habits

Protists are a highly diverse group of soil organisms with various ecological roles, such as predators, decomposers, primary producers, and pathogens. Not every protist prefers the same food; some are picky and specialised feeders. Many soil protists are predators of microorganisms, especially bacteria, but they may also feed on fungi, algae and other protists. Predatory protists can actively detect, capture and engulf their prey. Through this selective feeding behaviour, some protists influence the composition of microorganisms in the soil and root zone of plants (rhizosphere), reducing pathogens and increasing plant beneficial bacteria. Unlike fungi and bacteria, predatory protists do not rely on external enzyme secretion and membrane transport to absorb nutrients. Other protists (microalgae) are capable of photosynthesis and use CO₂ from the atmosphere to produce sugars (energy) and release oxygen. Yet other protists feed on dead organic material.

If you want to explore the feeding habits of protists in a visual way, watch the video “To eat or to be eaten – dinner time in the soil” from the Soilwatching series (external content). It is about 5 minutes long and was produced by Frederik Klinghammer and Edith Hammer from Lund University (external content).