Domain Eukarya, but not Animal, Plant, or Fungus

Photosynthetic Protists

These quite different organisms share the traits of being unicellular (occasionally colonial), aquatic and photosynthetic. They almost certainly are unrelated evolutionarily, however similar ecologically.

Phylum Rhodophyta

These are the most unusual algae, possessing chlorophylls a and d and simple, primitive chloroplasts, and never possessing flagella. The reddish color typical of these algae is due to an accessory pigment, phycoerythrin. Most species are marine and tropical. An example is:                     Polysiphonia This is a filamentous alga with distinctly different male (antheridia – A) and female (cystocarps – C) reproductive structures during the sexual phase of their lives. An asexual stage includes tetraspores (T). All reproductive structures occur with vegetative cells (V). Phylum Phaeophyta Some of these are the largest algae (or protists, if you group the Phaeophyta there), reaching lengths of nearly 100 meters. They possess chlorophylls a and c, like some of the unicellular algae, and store energy as the carbohydrate laminarin (named for a genus of kelp). Their frequently large size has required that some kind of internal conduction of dissolved substances occur, although they are never truly vascular. Most species are marine and are found in cool temperate regions. Examples are:                     Fucus A common intertidal brown alga on rocky coasts in regions of cool water. The sexes are separate in this form which spends most of its life as a diploid gametophyte. Female conceptacles (F) are located on the blades of female plants; they contain archegonia (O), which produce eggs. Male conceptacles (M) are located on the blades of male plants; they contain antheridia (A), which produce sperm. These are cross sections.                     Laminaria Another common brown alga, but found attached in deeper waters offshore. This genus includes some of the larger species of kelps. Here we see the relatively simple structure of the leaf-like blade in cross section. It has numerous zoospores (Z) on its surface. Phylum Chlorophyta This group of algae is mostly fresh-water, and is fairly diverse; it is the only group of algae that is not a dead-end, evolutionarily (i.e., it, alone, apparently gave rise to terrestrial plants). All members possess chlorophylls a and b, and store energy as starch; typically, they are not as large or as complex as many of the Phaeophyta. Examples include the following forms.
  One evolutionary trend seen among the green algae is that of increasingly larger colonies of simple, flagella-bearing cells. Gonium is a little raft of typically 16 cells, and represents the smaller colony end of this coloniality series. Volvox is a huge colony of hundreds of cells. By means of coordinated flagellar action, it swims with a tumbling action. Volvox reproduces both asexually (note internally budded daughter colonies - D) and sexually (note macrogametes (L) and microgametes (S) inside some colonies; these stain darker).

Filamentous algae consist of chains of cells. An example is Spirogyra, named for its large, spiral-shaped chloroplast (C). This alga reproduces sexually by a type of conjugation during which haploid filaments align and adjacent cells (gametes – G) combine to form diploid zygotes (Z).

                    Chara This is a fairly simple green alga of fresh water, with distinct reproductive structures (R), attached to the vegetative (V), or non-reproductive, cells. Both antheridia (A) and oogonia (O) can be seen.                     Ulva This is a very simple green alga of sea coasts. It consists of a couple of layers of very simple photosynthetic cells, in both the haploid and diploid portions of its life cycle.

Phylum Bacillariophyta These cells possess chlorophyll a and c, other, yellow-brown, pigments, and double shells containing silica.  Diatoms:  These organisms are either elongate (bilateral symmetry) or with radial symmetry.               Phylum Dinoflagellata (Pyrrophyta) These cells possess chlorophyll a and c, two flagella, and a shell of cellulose plates. An example is:                         Ceratium These organisms have several points or horns to their shells; flagella are not very obvious.


Phylum Euglenophyta
These cells have no cell wall (although they do generally have a definite, though flexible, shape), chlorophyll a and b, and possess a flagellum or two. An example is:                         Euglena The flagellum, which is difficult to see, pulls the cell through the water like a propeller; some forms are heterotrophic.

Fungus like Protists

There are at least two unrelated groups of organisms that are more like the fungi than any other group of multi-cellular organisms, but actually have some characteristics of organisms in each of the multi-cellular kingdoms. Since we do not have the material to distinguish these in laboratory, we will just consider this group of organisms as Slime Molds. An example is:


This organism shows both cytoplasmic streaming (frozen in this preserved specimen) and spore production. Note the pseudopod-like extensions of cytoplasm and the tiny spores scattered on its surface.

           Phylum Oomycota

Organisms in this group possess cellulose cell walls surrounding diploid cells; reproduction involves flagellated zoospores.
This is one of the water molds, a common type of fungus in this group, which also contains the infamous potato blight. You may be able to see sporangia or zoospores, but the most obvious identifying feature is the spherical oogonium (O), with rather large gametes inside and finger-like antheridia (A) curled around it; hyphae (H) are also present.   
        Protozoa (the animal-like protists) All were once considered fairly closely related because of their clear animal-like traits (motility, e.g.), they are currently considered to exhibit widely varied levels of relatedness. In spite of the possible lack of phylogenetic closeness, they do share such characteristics as heterotrophy (mostly via ingestion of nutrients) and motility; many are rather complex and possess real behaviors.
     Phylum Zoomastigina
  The feature that is most distinctive is the flagellum, given their eukaryotic condition and absence of chloroplasts. Flagella are frequently relatively long and few in number, but are best distinguished by how they move the cell: either pulling the cell by a propeller-like movement near the tip, or pushing the cell like the tail of a tadpole or sperm cell. Examples are:       Trichonympha
  These organisms (Y) have many long flagella; they are mutualists in the guts of termites and related insects, digesting the cellulose that has been eaten. The slide is a smear of termite gut contents.
                        Trypanosoma These organisms have a single flagellum held against the cell by a membrane; they are blood parasites transmitted among species of birds or mammals by tsetse flies. The slide is a blood smear; note RBC (R), WBC (W) and trypanosomes (T).     Phylum Rhizopoda (Sarcodina) The distinctive feature for this group of protozoans is the use of pseudopods for locomotion; pseudopods are lobes of cytoplasm that push out from the body of the cell. Some species possess tests (tiny shells), but the cells themselves have no fixed shape. Examples are:                     Amoeba This organism is fairly large for a single cell. It has an obvious nucleus (N) and pseudopods (P); vacuoles (V) are often visible, and the cytoplasm appears grainy.                     Foraminifera These organisms, which capture food and locomote using pseudopods, are most easily distinguished by their tests, which are bilaterally symmetrical and often resemble tiny snail shells. The slide is of empty shells.             Phylum Sporozoa This group consists entirely of endoparasites, which have no locomotor structures and frequently reproduce via multiple fission and a complex life cycle. An example is:                         Eimeria This is a gut parasite of mammals. The slide shows numerous parasite cells (E) in the gut lining (G).               Phylum Ciliophora This is the largest group of protozoans; they are clearly the most complex structurally, and probably behaviorally as well. They are distinguished by the presence of cilia, which are frequently relatively short and abundant; cilia are best distinguished by their mode of action which is oar-like on the power stroke and limp on the recovery stroke. They also possess complex nuclei. Examples are:                         Stentor This is a filter-feeding ciliate, which generally feeds attached to the substrate in a funnel-shaped form, but can release from the substrate and adopt various forms to swim to another locale. It has a large, segmented nucleus, which looks like a string of beads (N).                         Didinium This is a one-celled predator (D)! They feed on paramecium, (P) which are typically larger than themselves; after attacking, they swallow them whole. They have a large, ribbon-shaped nucleus and their cilia are restricted to a few bands.                         Paramecium Shaped something like a slipper footprint, these are entirely covered with cilia. They have one macronucleus (N) and two or more micronuclei; the latter are exchanged during conjugation - their form of sexual reproduction. Two different slides of this critter demonstrate both fission (asexual) and conjugation (sexual). A paramecium undergoing fission shows the transverse fission plane (F) and dividing nucleus (N). Two pairs of paramecium are engaged in conjugation.