What roles do protists play in the environment?
Protists are considered to be all eukaryotic organisms excluding plants, animals, and fungi. In contrast to prokaryotes, all eukaryotes have plasma membranes made up of phospholipid bilayers, membrane-bound and organized organelles including a nucleus, and a cytoskeleton structure.
Protists may be photoautotrophic or chemoheterotrophic, meaning they may play the role of producers or consumers in the environment. Without rigid cell walls, heterotrophic protists have the ability to ingest food completely through membrane enfolding, making them more competitive. They may also act as decomposers or parasites. With the development of photosynthetic organelles, autotrophic protists are also more productive than their prokaryotic counterparts. With their abundance, they serve as a leader in global carbon fixation.
Especially in the case of marine habitats, protists play an essential role in food chains. Phytoplankton serve as the heterotrophic base of the chain, larger protists called zooplankton consume these organisms, and then larger animals are able to feed on these, in turn.