The Cell: A Visual Tour Of The Building Block Of Life, Jack Challoner, c.2015

This is pretty cool; classification of living organisms has really changed since my college days. In addition, different biologists use different classifications, and in much of the literature, the terminology is used interchangeable.

There are six kingdoms or domains:

• animal
• fungi
• plant
• protists (crosses over into each)
• archaea
• bacteria

The first four are eukaryocytes:

• animal
• fungi
• plant
• protists

The latter two are prokaryoctyes (old term, containing both Monera):

• archaea: more closely related to animals than to bacteria
• bacteria

Kingdom Protista is all eukaryocytes that cannot be placed in animal, fungi, or plants.

• Animal, plant, and fungi are multicellular
• Archaea and bacteria are unicellular
• Protista cross the seam: unicellular and multicellular.

One still sees the Kingdom Monera as recently as 2012. Monera is an archaic term for prokaryocytes; Monera has now been divided into Bacteria and Archaea.

What is the difference between protists and protozoa.

According to this 2012 site, which still uses the term "Monera," the Kingdom Protista is again grouped into three subgroups: protozoa (animal-like); protophyta (plant-like); and, slime moulds. So there you have it. Remember: if you have an organism that is a eukaryocyte (nucleus), you want to try to make it animal, plant, or fungi. If unable to definitely call it plant, animal, or fungi, then call is what is most looks like ( -- animal; -- plant; -- fungi). If the eukaryocyte (nucleus) looks animal list, then the protist is protozoa; if plantlike, then protophyta; if fungi-line, then a slime mold.

Protozoa are mostly aquatic. "Famous protozoa" are the parasitic protozoa: malaria, toxoplasmosis, cryptosporidiosis, leishmaniasis (considered the world's second-deadliest parasite) -- all are apicomplexia (contain spear-like organelle to pierce other eukaryotic cells).

Protozoa are divided into four phyla based on methods of movement and not based on phylogenetic.

• flagellates (or Mastigophora),
• amoeboids (or Sarcodina)
• sporozoans (or Sporozoa, Apicomplexa) -- the deadly parasites (malaria, toxoplasmosis, cryptosporidiosis, leishmaniasis)
• ciliates (or Ciliophora)

How do sporozoans move? Sporozoa, being parasitic, lack locomotor appendages and as a result move by minute contractions of small contractile fibrils. This motion was previously accredited to the organisms sliding on a mucus secretion.

Parasites: sporozoans (apicomplexa) can live in almost any animal (including human beings); they can even live inside other apicomplexa. 

Most protists cannot move. 

So, where do algae fit? Algae = seaweed. Alga is Latin for seaweed

Huge disagreement. No definition universally accepted. Polyphyletic: no common ancestor. Photosynthetic (so they have organelles) and so eukaryocytes. But can be unicellular or multicellular. Having said that, apparently the cyanobacteria (blue-green algae) -- prokaryotes -- photosynthesize, and are considered algae by some (hence the name). My hunch: over time: blue-green algae, being prokaryotes will be placed among the Monera (bacteria or archaea) but due to history will retain the common name, blue-green algae for a long time; only when cyanobacteria becomes standard/common usage (and that may never happen) will  blue-green algae be understodd by all to be bacteria (cyanocbacteria).

But this is the problem with trying to classify algae/cyanobacteria with Bacteria: Algae have photosynthetic machinery ultimately derived from cyanobacteria that produce oxygen as a by-product of photosynthesis, unlike other photosynthetic bacteria such as purple and green sulfur bacteria.

The study of marine and freshwater algae is called either phycology or algology. Phycology comes from Greek fukos or phykos which is associated with paint or dye. Ancient Egyptians used cosmetic eye-shadow derived from seaweed (any color: black, red, green).

Algae are further divided into three separate supergoups; another grouping is based on
plastids.

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From Plausibility of Life: Resolving Darwin's Dilemma, Marc W. Kirschner and John C. Gerhart, p. 51:
Among the eubacteria are the cyanobacteria (once misleadingly called blue-green algae), which invested oxygen-generating photosynthesis by which the entire oxygen atmosphere of the earth was slowly produced from water. Thanks to their work, oxygen probably increased to a few percent in the atmosphere by two billion years ago (presently it is 21 percent).

At roughly that time a second phase of innovation occurred: the archaebacterial line split into two lines, one leading to the modern archaebacteria and the other to eukaryotic organisms (organisms which contain a nucleus). These now include diverse single-celled protists (what used to be called protozoa, for example, an amoeba or paramecium) and the great multicellular kingdom of plants, animals, and fungi.

From this link:

The nuclear envelope(NE) consists of an inner and an outer membrane enclosing the perinuclear cisterna or perinuclear space. The outer nuclear membrane is studded with ribosomes and continuous with the membrane of the rough endoplasmic reticulum (RER). Therefore, direct continuity exists between the lumen of the nuclear envelope and the rough endoplasmic reticulum,