A Brief Survey of the

Handbook of Protoctista

by Richard L. Howey, USA


This book is an enormous undertaking with 914 pages, a large format, and is filled with both optical and electron photomicrographs, and has 60 contributors who are experts on specific groups of organisms. If you can find a copy of it for $200, jump at it. In fact I just checked Amazon and there is a used copy available for $182.50 on up to a new copy for $2,432.64 + $3.99 shipping. However, a second edition is to be published in early January of 2015 for $474.95 but Amazon has a pre-published guaranteed price of $452.20. I bought a copy when it first came out and felt distressed to have to pay $80. Now it is a classic reference work and even though it was published almost 25 years ago (1990). In a way, I am surprised that a second edition is forthcoming given the cost of production and competition from projects like the Internet Encyclopedia of Life inspired by E.O. Wilson. Nonetheless, this is an exceptionally informative work and I won’t ever sell my copy; they’ll have to pry it from my cold, dead hands. (Out here in Wild Wyoming, we like to talk that way.)

The volume has 4 distinguished editors: Lynn Margulis from the University of Massachusetts, John O. Corliss from the University of Maryland at College Park, Michael Melkonian from the Botanical Institute of Cologne University in Germany, and David J. Chapman from the University of California at Los Angeles. In addition, there was an editorial coordinator, Heather I. McKhann also from UCLA. The editors had the difficult task of bringing together contributions from 60 specialists, imposing a consistent format, and trying to establish terminological uniformity. This last issue became one of the most contentious and given the strong personalities involved, it is not surprising that there were some strong disagreements. Two major examples need to be mentioned.

1) Margulis insisted upon using the awkward name “protoctista” for this kingdom whereas Corliss and others much preferred the term “protista” which has a tradition dating back at least as far as Ernst Haeckel. This issue was never resolved and Margulis wrote about protoctists and Corliss about protists. (Not that it makes any difference, but I’m afraid that I’m on Corliss’s side on this one.)

2) Margulis also insisted on employing the term”undulipodia” instead of “flagella” when applied to eukaryotes. She rightly points out that this structure is different from that possessed by the bacteria which belong to another kingdom or two. Again, Corliss retains the more traditional term and speaks of flagella when discussing protists. (Once again, I’m afraid I’m on his side here.) Perhaps it is important to reinforce this distinction by way of terminology, but surely something a bit more felicitous than “undulipodia” could be concocted. I think one of the barriers to attracting more students into the serious pursuit of the biological sciences is the massive maze of terminological thickets and brambles. All scientific disciplines require a certain amount of technical jargon. At least, in contemporary physics, one finds a certain amount of creative whimsy with quarks (borrowed from Lewis Carroll) which have properties such as upness, downness, and strangeness. One physicist has suggested that if 2 more are discovered, they should be named Truth and Beauty. There is also String Theory and the T.O.E. (Theory of Everything), not to mention black holes, antimatter, and worm holes.

By way of contrast, consider this passage from the handbook:

“The antigenic nature of this glycoprotein can be changed repeatedly; each variant surface glycoprotein (VSG) is associated with a serologically identifiable variable antigen type (VAT). As trypanosomes multiply by fission in the ascending parasitemia, as particular VAT, the hemotype, forms the major part of the population. When the host mounts an antibody (IgM) response to the homotype, the parasitemia goes into remission as trypanosomes of the homotype VAT are killed off.” (P. 229)

Or a passage by a different contributor:

“Within the cytoplasm of developing thraustochytrid thalli is a normal complement of eukaryotic organelles: mitochondria with tubular cristae, lipid granules, multivesicular bodies, and Golgi bodies with the forming face usually closely associated with the nuclear envelope. The centrioles, present throughout interphase, are located in a shallow pocket of the nuclear envelope. Rough endoplasmic reticulum, which may form arrays of parallel cisternae (Moss, 1980), is usually associated with the cytoplasmic side of the dense plug of sagenogen.” (Pp. 393-4)

So, I’m glad we got these things cleared up. Clearly, this is not a book for beginners and I don’t mean to minimize the difficulties of writing about the morphological, behavioral, and ecological intricacies of these organisms, but some of this jargon is unnecessarily technical and obscure. It becomes parallel to Bureaucratese and Pentagonese. In my own discipline of philosophy, I used to tell students that they can be clear without being superficial and that abstruse and obscure modes of expression are rarely profound or insightful. One can use tables, graphs, charts, drawing, photographs, equations, and technical jargon to transmit information, but unless there is also some passion, some excitement and clarity, then the communication is deficient. When science becomes entrenched in obscurantist modes of writing and talking, the scientists should not be surprised that few students are attracted to their disciplines. This is especially aggravating in this kind of case where the kingdom Protista contains come of the strangest, most intriguing, and downright alien organisms imaginable.

The Handbook of Protoctista has two subtitles, the first of which is:

“The Structure, Cultivation, Habitats and Life Histories of the Eukaryotic Microorganisms and Their Descendants Exclusive of Animals, Plants, and Fungi.” This is fairly straightforward and helpful once you understand that ‘eukaryotic” simply means organisms which have nuclei that are surrounded by a membrane. One might quibble about whether or not all of them are truly micro-organisms, since some are macroscopic (i.e., big enough to see with the naked eye) and others are, what we might call “meso-scopic”, that is, big enough be examined with a low power magnifying glass. The real point, however, is that the only way you’ll really learn much about these organisms is through microscopic examination. So, sometimes we have to be a bit flexible and generous in our interpretations of terminology.

Naturally, there are complicated exceptions and editorial disagreements arise as is evident in the Introduction written by Lynn Margulis. In section 12 of the Introductions, she addresses the issue of “Size and multicellularity: Protoctist vs. protist”. She asserts:

“Thus we restrict the term ‘protist’ to an informal usage. Protist, in this handbook, refers to the protoctista members of the microcosm that require the use of microscopes for their visualization. Whereas the term ‘protoctist’ includes all members of the kingdom ; ‘protist’ refers to only the small organisms, generally composed of a single or only a few cells.”

A minor, but not insignificant tissue, is reference to this tome as a “handbook”–it is anything but, requiring two arms just to lift it. Earlier, she points out that Protoctista range in size from organisms like the chlorella which are only about 1 micron in size to the giant kelps which range up to 150 feet.

The second subtitle is:

“A guide to the algae, ciliates, foraminifera, sporozoa, water molds, slime molds and the other protoctists.”

This is modestly helpful, because it informs us that many of our old friends–Amoeba proteus, Paramecium, Euglena, forams, and slime molds are to be found here. This kingdom, as presented in this volume, has 36 phyla and 19 classes! Too many! As a consequence I suspect that in the next few decades we’ll see the creation of a number of new kingdoms in order to tidy things up a bit.

Now, however, we need to go back to section 3 of the Introduction: “There are no single-celled animals or plants.” Being a bit slow-witted, it took me a while to understand what she was getting at, since she does talk about unicellular and multicellular protoctists. In brief, Margulis views the terms “unicellular” and “multicellular” as acceptable when talking about protoctists, but when talking about plants and animals, it is a mistake to talk about “unicellularity” because they are by definition multicellular. Here I strongly disagree with the first part of her claim. In my view, as I have briefly argued elsewhere The Unicellular Fallacy protists, such as Paramecium, Amoeba, Navicula, etc., are by definition NOT unicellular, but are rather complete, self-contained organisms radically different from neurons or epithelial cells. This is a difficult issue, because the Margulis kingdom of Protoctista includes organisms such as the giant kelps which are clearly multicellular. This is one major reason why I prefer the notion of the kingdom Protista which as she says “refers to only the smaller organism, generally composed of a single or only a few cells.” It is appealing to me (with a major qualification which I’ll discuss in a minute.) I suspect that the giant kelps and most of the other clearly multicellular protoctists require new kingdoms. As Margulis rightly argues size alone is hardly a sufficient criterion for making fine discriminations, but neither is it irrelevant. In the Mammalia, one has everything from the pygmy shrew to the elephant and the blue whale, but they are clearly multicellular and share a significant number of characteristics that make them mammals.

However, in this kingdom of Protoctista, it is important to ask: what is the relationship between slime molds and foraminifera, between dinoflagellates and coccolithophores, between ciliates and giant kelp? With this conception of Protoctista as defined by Margulis, these questions become extremely difficult, if not impossible, to answer. If, though, we accept the restricted sense of Protista as Margulis describes it, namely limited to smaller organisms and consisting of “a single or only a few cells,” then, I think, we end up with a more comprehensible kingdom. Here is where I would introduce my major qualification. We must not think of them or describe them as cells; they are individual organisms or aggregates or colonies, but not cells. Giant kelp do consists of cells, so what do we do with them and other such anomalies? Well, a couple more kingdoms won’t hurt and might even help keep things better organized. In any case, though I have been a lone voice crying out in the wilderness of Wyoming, I think that we should be well-served by abandoning the concept of unicellularity.

There are reasons for resisting this suggestion and they depend in large part on the fact that there are some colonial organisms with “cells” that are very much like independent non-colonial organisms. For example, sponges (and many other creatures including humans) have amoebocytes which can serve a variety of functions within the larger organism. However, admittedly, the matter with sponges is not easy and straightforward. Experiments have been done with 2 different species of sponges which have been disassociated and vitally stained so that one group is perhaps red and the other blue. These components are then mixed together and reaggregation does seem to be species specific at least in certain species. There have been other experiments using 2 specimens (of the same species) to study whether or not, at this level, there is a “self/not-self” biochemical recognition response. The results are largely ambiguous. A student of mine (Mr. Hanly) and I tried this experiment using the primitive Placozoan, Trichoplax adhaerens and using the vital staining technique, found the there was no “self/not-self” recognition response in the organism. After we finished the project, he took a photograph of one of the Trichoplax showing the mixed colors of the cells, had it framed and gave it to me. You can see it below.

Another sort of difficulty arises with organisms such as Volvox, Anthophysis, Synura, and Conochilus The voluptuous Volvox is a delight to almost every microscopist. It consists of hundreds to thousands of “units’ or “cells” depending on the species. Here, for me, the question arises: Can a colony be composed of cells or is it an aggregate of organisms? Let’s start with Conochilus which is an elegant colonial rotifer. I first found these in a reservoir at an altitude of about 6,000 feet and they are wonderful to observe. Google Images provide a selection of images of this intriguing rotifer.

During the process of collecting, individuals occasionally break off from the colony and single rotifers separate from their original colony. Can the individuals survive alone? Can they start a new colony? I’m not sure anyone knows. Rotifers are multicellular so, there is a fair chance that they may be able to establish new colonies once separated from their original one. Clearly, there are colonial organisms, such as, siphonophores where the individual members that constitute the colony are interdependent for their survival suggesting that we need to find clearer language for talking about these different sets of configurations. Off the top of my head, I’m inclined to talk about Kellicottia as an aggregation of rotifers rather than a colony. While there is a relatively small number of individuals in a Kellicottia aggregate, I would estimate that the upper limit is around 30.The important thing to note is that it is not a fixed number. There are certain algae where a given species will have a specific number of components or “cells”, but there are many protists where the number is variable even within a given species.

Anthophysis vegetans poses some intriguing problems. It is, in one sense, an Über-colony. It is in fact a remarkably strange organism. If you encounter a fully-formed mature colony, it looks like a series of brown branching stalks which at the very tips of the branches have wheel-like colonies of flagellates. When the larger colony is disturbed–when, for example, they are transferred from a culture dish, put on a slide and subjected to the pressure of a coverglass–some of the colonies at the tips of the branches may separate from the tips and go spinning off through the water.

So, here are my puzzlements: How do these brown branches get formed by this aggregate of flagellates? When the aggregates break off from the tips of the branches and go swimming away, do they form new Über-colonies with branches? What triggers the creation of a new branch and the development of a new spherical colony? These are not trivial questions, because each such puzzle we can solve tells us something more about the incredible subtlety and complexity of life. This complexity, however, has nothing at all to do with the fabrications of intelligent design “theory”; nature frequently displays complexity in the form of Cruelly, Random, Ephemeral, Whimsical Design (CREWD). As far as my questions regarding Anthophysis are concerned, I suspect that nobody yet knows the answers to them, in part, because governments prefer to support the creation and production of new weapons of destruction over and above the study of protists, perhaps with the exception of a few pathogens that might be modified for use in biological warfare.

Synura uvella is a somewhat larger aggregate of flagellates than Anthophysis, but Synura doesn’t have a stalk. It can reproduce at an incredible rate and produce “blooms” which give the water a distinct smell of cucumbers. Nature is always pushing at the edges, the limits, and I find this consoling since, in my eccentric (and often random and unintelligent fashion), I keep trying out experiments which, on a strictly rational basis, seem either wildly eccentric, absurd, or just silly.

Volvox is a world-class enigma. The largest species Volvox globator consists of thousands of cells and has a wild model for reproduction. Here again Wim van Egmond provides us with splendid images.

A large specimen can be 2000 to 3000 microns in diameter and so is just visible to the naked eye. It appears to be a hollow sphere, but clearly there is liquid within and some special elements or “cells’ floating within. However, let’s first discuss the outer surface. The “cells” are small and each possesses 2 flagella and a red “eye spot” or light sensor. These are crucial in keeping the organisms properly oriented with regard to sunlight since the “cells” also have chloroplasts for generating food. The “cells” are connected by minute fibrils and these undoubtedly have something to do with coordinating movement for the sphere. It wouldn’t do to have half of the cells striving to go north and the other half striving to go south. How does all of this work? Again, no one knows for sure. Wichterman wrote a book on Paramecium, Tartar wrote a book on Stentor, Giese wrote a book on ‘Blepharisma–why hasn’t anyone done a book devoted to Volvox? There’s a project for some bright, young researcher who wants to age gracefully into becoming an expert on the mysteries of this marvelous organism.

Frequently, in fact almost always, when looking at a good collection of Volvox, one will observe specimens which appear to have a miniature colony or two or several within the meta-colony and that is exactly what they are. A Volvox with these sub-colonies or “daughter” colonies as they are known, is reproducing. Volvox #1 may have all female sub-colonies, Volvox #2 might have all male sub-colonies, and Volvox #3 might have a mixture of male and female sub-colonies. Now here’s challenge for a sexologist! Is there some way of determining in advance which meta-colonies will produce which set of sub-colonies? I suspect there is by means of some highly sophisticated molecular biological procedures, but I also suspect that no one has ever yet tried to make such determinations in Volvox.

What this Handbook most certainly does do is raise a series of fascinating conceptual issues, including, but by no means, limited to taxonomic considerations and, in addition, presents intriguing information about some of the weirdest and most bizarre, as well as beautiful, creatures to be found on planet Earth. For some of the larger groups, one may find the discussions too abbreviated and rather disappointing. This is especially true for organisms such as amoebae, ciliates, diatoms, and desmids to mention a few. However, one has to remember that this volume is a survey and covers a very wide range which is simultaneously a strength and a weakness. It does, however, provide extensive bibliographic information for further reading and research. It also has the virtue of providing a glossary of terminology.

One of its greatest strengths is that it introduces us to a large number of quite small groups, many of which are very likely completely unfamiliar and gives us further information and splendid optical and electron photomicrographs regarding organisms with which we have only a nodding acquaintance, such as, coccolithophores. These are very small creatures which can occur in such phenomenally large numbers in the North Atlantic as to produce aquatic “clouds” that can be detected by satellites. Coccolithophores are relatively well-known among microscopists because of their elegant structure as revealed by scanning electron microscopy as you can see here.

However, how many of you are familiar with the members of the phylum Xenophyophora? (Pp. 135-38) These odd lumps have been known since the latter part of the 19th Century during the period of extensive deep sea dredging by a series of major expeditions. These organisms have posed great challenges in terms of classification, because all of the material examined has been preserved or studied briefly, usually in fragments when dredged up and brought on shipboard. These oddball creatures illustrate beautifully what happens when human beings start trying to get everything in order. Dr. Řle Secher Tendal of the University of Copenhagen, who is the contributor on this phylum comments:

“As members of an unrecognized group they were often mistaken for poorly preserved fragments of sponges, coelenterates, bryozoans, or ascidians, or they were regarded as inorganic concrements consisting of foraminifera tests, radiolarian skeletons, sponge spicules, or mineral grains.

Like many small groups of organisms, their eccentricities pose major problems in terms of classification even at the phylum level. This is readily seen with the exclusively fossil groups like graptolites which have been bounced around taxonomically for over a century. It’s not surprising that the Xenophyophores have been a challenge. Most of them range in size from a few millimeters to about 7 centimeters, although one specimen of a “Stannophylum”, was of a flat form and measured about 25 centimeters in diameter, but was only about 1 millimeter thick.

So, what are these weird thingies–animal, vegetable, or mineral? Interestingly, they have long been regarded as some bizarre variant of a Rhizopod, in other words, something related to the amoebae. If you look at the photographs in Tendal’s article, you would never think that these had any relationship to anything amoeboid and, in fact, Haeckel thought they were sponges. Tendal describes Xenophyophores as:

“...a plasmodium enclosed by a branched tube system made of a transparent, cementlike organic substance. The complex is called ‘granellare.’ Besides numerous nuclei the cytoplasm contains huge numbers of barite crystals (‘granellae’). Pseudopodia are supposed to be extended through the free ends of the granellare branches.”

A plasmodium is a mass of protoplasm with many nuclei, but no internal boundaries, it is without any walls or “cell” membranes. In this respect, it bears some resemblance to the true slime molds.

Seemingly a distinctive feature is the occurrence of large quantities of barite crystals. Their appearance is highly variable in large part due to the sorts of foreign objects (xenophae) which they glue to themselves. Since these are deep sea organisms, most of the usual sampling techniques cause extensive damage to the specimens. As intriguing as these creatures are, much of what has been reported about them is conjectural and much more research remains to be done. But, alas, they have no economic significance, so studying them is a very, very low priority for most researchers.

As it happens, this is true for a large number of the other strange and splendid creatures which appear in this handbook. As a consequence, this volume is in many respects more a guidebook than a handbook, a book of hints, suggestions, and conjectures which one can hope will lead both professionals and amateurs to try to discover more about these remarkable creatures.

All comments to the author Richard Howey are welcomed.

 

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