Protists are eukaryotes and they have a nucleus.  Majority are unicellular though there are some exceptions. Protista or protist was first used by Ernst Haeckel in 1866 Some protists include amoebae, green and brown algae, and euglenas. Most live in liquid envoirnments and are a vital part of that ecosystem such as algae to plankton. A few species are responsible for serious human diseases such as Malaria and sleeping sickness. They can be pathogens for both plants and animals. Protists can filter-feed, absorb their food, or use photosynthesis. Protists can reproduce sexually through gametes or asexually by binary fission. They can be classified in three different ways; animal-like, plant-like, and fungus-like. Animal-like protists are called protozoa. Protozoa are heterotrophs. Plant-like protists are algae, and are autotrophs. Fungus-like protists can decompose and absorb their food and have external digestion.