Station 5: Supergroup Unikonta

Tubulinids

The amoebozoa clade is a major taxonomic group containing about 2,400 described species of amoeboid protists, often possessing blunt, fingerlike, lobose pseudopods and tubular mitochondrial cristae.

Amoebozoa includes many of the best-known amoeboid organisms, such as Chaos, Entamoeba, Pelomyxa and the genus Amoeba itself. Species of Amoebozoa may be either shelled (testate), or naked, and cells may possess flagella. Free-living species are common in both salt and freshwater as well as soil, moss and leaf litter. Some live as parasites or symbiotes of other organisms, and some are known to cause disease in humans and other organisms.

While the majority of amoebozoan species are unicellular, the group also includes several varieties of slime molds, which have a macroscopic, multicellular stage of life during which individual amoeboid cells aggregate to produce spores.

Genus Amoeba

Tubulinids form tube like pseudopodia and are covered with cell membrane. They change, all the time, their body-shape. They feed by phagocytosis. Freshwater forms have contractile vacuoles to expel excess water. Common example is Amoeba proteus.

Slime Molds

Slime Molds were originally considered as being a type of fungus and placed in the Kingdom Fungi. However, cellular characteristics and DNA analysis has indicated that they are a separate group and not in the fungi.

Slime Molds are naked protists which feed by phagocytosis.  Slime Molds have multinucleate protoplasmic masses called plasmodium. These reproduce asexually by spores formed in walled sporangia in a cluster called fruiting body. Spores develop into amoeboid or flagellated gametes. Cellular Slime Molds live as solitary amoeboid cells. Under unfavorable conditions these can form aggregations called pseudoplasmodium (the form that is most often encountered). When favorable conditions return sporangia in a fruiting body produce spores. The spores give rise to single cells to complete the cycle.

Genus Stemonitis

Stemonitis is a distinctive genus of slime molds found throughout the world (except Antarctica). They are characterised by the tall brown sporangia, supported on slender stalks, which grow in clusters on rotting wood.

Genus Physarum

Physarum is a large genus of true slime molds, accounting for about 20 percent of the species of the phylum Mycetozoa (Myxomycetes). Physarum polycephalum, a fast-growing species, is the most notable; it has been used widely in physiological experiments in protoplasmic streaming and nuclear behavior.

The opisthokonts or Choanozoa are a broad group of eukaryotes, including both the animal and fungus kingdoms, together with the eukaryotic microorganisms that are sometimes grouped in the paraphyletic phylum Choanozoa (conventionally assigned to the protist "kingdom"). The opisthokonts, previously called the "Fungi/Metazoa group", are generally recognized as a clade.

The fungi and animals and their close unicellular relatives will be discussed and examined in future labs.