Protists: For what two purposes do sarcodines use their pseudopods?

Answer 1

Whoa, that answer above is rather long. In short: they need their pseudopods to move and get food.

Answer 2

Protists (IPA: /ˈprəʊ.tɪst/ (RP); /ˈproʊ.tɪst/ (GenAm)), Greek protiston -a meaning the (most) first of all ones, are a diverse group of organisms, comprising those eukaryotes that are not animals or plants. They are usually treated as the kingdom Protista or Protoctista. The protists are a paraphyletic grade, rather than a natural (monophyletic) group, and do not have much in common besides a relatively simple organization (unicellular, or multicellular without highly specialized tissues). Essentially, the Kingdom Protoctista is made up of organisms which cannot be classified into any other kingdom.

Protists were traditionally subdivided into several groups based on similarities to the higher kingdoms: the animal-like protozoa, the plant-like algae, and the fungus-like slime moulds and water moulds. These groups often overlap, and have been replaced by phylogenetic classifications. However, they are still useful as informal groups for describing the morphology and ecology of protists.

At one time, bacteria were also considered protists, under the three-kingdom system of Animalia (corresponding closely to the modern kingdom), Plantae (which included Fungi as well as plants), and Protista (everything else). See kingdom (biology). However, most recent texts treat bacteria separately.

The taxonomy of protists is still changing. Newer classifications[1] attempt to present monophyletic groups based on ultrastructure, biochemistry, and genetics. Because the protists as a whole are paraphyletic, such systems often split up or abandon the kingdom, instead treating the protist groups as separate lines of eukaryotes. The recent scheme by Adl et al. (2005)[2] is an example which does not bother with ranks (phylum, class, etc.).

Some of the main groups of protists, which may be treated as phyla, are listed in the taxobox at right. Most have been established as monophyletic, though for some this is still uncertain; for instance the metamonads, which may be paraphyletic to other excavates, and the Chromista, which may be paraphyletic to the alveolates (see chromalveolates). Various smaller groups of protists also existed; these are listed under the traditional categories, linked to above.

For more discussion of relationships between different protists and their evolution, see eukaryote or the articles referenced below.

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