Kingdom Protista

  General

· Kingdom Protista consists of organisms that don’t seem to fit anywhere else.

· Protists are some of the earliest living things on Earth. The first eukaryotic cells are thought to have been protists. They gave rise to fungi, plants, and animals.

·  The oldest fossils of eukaryotic cells are 1.5 billion years old although the earliest eukaryotic cells may have arisen 2.1 billion years ago. The oldest fossils of prokaryotes are 3.6 billion years old.

·  Most are small, single-celled organisms that are not necessarily related to one another.

· Protists are eukaryotes lack the specialized features of fungi, plants, and animals, although they do have membrane-bound organelles.

·  Three large taxonomic groups show huge diversity

i.         Animal-like

                                    (1)       All motile

                                    (2)       Includes Sarcodines (e.g., Amoeba proteus), Ciliates (e.g., Paramecium caudatum), and Flagellates (e.g., Euglena sp.).

                        ii.        Plant-like

                                    (1)       Mostly non-motile; photosynthetic

                                    (2)       Often called algae or seaweeds

                        iii.       Fungus-like

                                    (1)       These grow in dark, shady habitats and are called slime molds.

                                    (2)       Most are colorful and can be found underneath rotting logs or leaves.

 Respiration - protists are almost exclusively aerobic.

 Nutrition

· Various feeding strategies

i.         Some have chloroplasts and manufacture food like plants

                        ii.        Others ingest food like animals.

                        iii.       Others absorb food like fungi.

Reproduction - all are capable of asexual reproduction but some reproduce sexually as well.