by Richard L. Howey, Wyoming, USA
When we look around at the creatures which share our world, we can find all sorts of extraordinary beings—some beautiful, some terrifying, some cuddly, some comic, some ugly—all with their own public relations staff. Nature cinematography is a wonderful educational tool, an indispensable technique for scientific investigations, and a high art form. Through the skill, dedication, courage and occasional touches of madness of these cinematographers, these intrepid observers allow us to see wombats, giraffes, sharks, meerkats, lions, tigers, hippos, whales, birds of paradise—the list goes on and on.
There is, however, another whole dimension of creatures who don’t have publicity agents—micro-beasties. It is true that there are some truly extraordinary photomicrographs of such organisms and Micscape has been blessed by the generosity of people like Wim van Egmond, Jan Parmentier, Dave Walker and Maurice Smith who have shared many of their remarkable images with us. There is also some splendid micro-cinematography and videography which has revealed new and exciting facets of the micro-world. Nonetheless, it is fair to say that micro-beasties certainly have not gotten equal time and attention and, as a consequence, some of the most bizarre, alien, weird, fantastic, indeed phantasmagorical, creatures remain virtually unknown outside of the world of a few specialists.
Imagine having to create a whole new phylum to accommodate a single organism! Offhand, I know of three such instances in the 20th Century during a period of taxonomic optimism. In the first instance, the organism was first described in 1883 by Schulze, who proposed in 1912 that it was the planula stage of a hydromedusan. Others thought that it was a large and bizarre amoeba, an early stage of a sponge or coelenterate, or a very primite non-segmented worm. This creature is know as Trichoplax adhaerens as it has three distinct cell layers and it does strongly adhere to the substrate. What’s so strange about this beastie? Well, it does, at times, look like a large amoeba, except that it has a nice rosy-pink color. But even stranger, Trichoplax is covered with flagella. Now whoever heard of a flagellated amoeba? Well, actually there are at least two genera of such odd amoebas, but they only have one or a few flagella—Trichoplax is covered with them. It has only three layers of cells; it can lie dormant on the substrate looking like a piece of uninteresting detritus; it has been found more often on the sides of aquaria than in collections from the wild; but perhaps its most remarkable feature is its ability to string itself out so that it looks like 2 or even 3 or 4 amoeboid-like creatures connected by thin protoplasmic bridges in which one can observe protoplasmic streaming. But I have already written an article for Micscape on Trichoplax, so I won’t repeat it all here. If you want to know more about this strange creature, you’ll have to look up the article, and as a bonus, you’ll get a good idea of what Trichoplax looks like, since Wim van Egmond did a terrific drawing of it for that article.
The second instance involves a creature which was first described 35 years ago, but had new a phylum created for it only 5 years ago. Shades of Trichoplax! This creature is Symbion pandora and the phylum created for it is called Cycliophora—”the bearer of a small wheel”. What’s so strange about it? Well, for starters, it lives on the mouth parts of lobsters. It is called Symbion because it is a symbiont on the lobster and pandora because it embodies at least two mysteries that might have been in Pandora’s box: 1) it may be a missing link between two other phyla—the entoprocts and the ectoprocts and 2) as Peter Funch, a co-discoverer of the organism, remarked regarding its uniqueness, “its digestive system collapses and is reconstituted into a larva that is released to develop into a new adult.” The creature had been noticed in the 1960s, but no one took much notice and it is not a rare creature, since the researchers stated that when they started looking, they found it in about half the Norwegian lobsters they examined and each had hundreds, or sometimes thousands, of Symbion. However, Symbion doesn’t exactly jump out at one, since its size is about the size of this dot “.”.
Another group of Danish scientists, just this past year , proposed the creation of new phylum for a 0.1 mm critter found in samples taken from a well in Greenland in 1994. It has the heavy name of Limnognanthia maerski and has had the phylum Micrognathozoa created for it, as it has a very complex set of jaws. It shares another unusual feature with a number of other micro-animals; it is parthenogenic, that is, all the organisms are female; no males have been found. In both the lobster lips’ case and this deep arctic well case, we have instances of organisms that have adapted to unusual and/or extreme environments. As we continue to explore such habitats, we shall discover many more unusual creatures that remain hidden from us now. A number of professional biologists have revived interest in odd or extreme environments in the last decade and, as Bill Amos’s wonderful article on tree holes shows, there are still lots of interesting niches remaining to be explored.
Another group of “wondrous strange” beasties was revealed surrounding volcanic funes in the depths of the ocean by the submersible Alvin—tube worms 8 to 10 feet long with brilliant red tentacles, large clams with a deep red hemoglobin pigment, unusual crabs and the famous “dandelions”. These are fragile anemone-jellyfish-like creatures that disintegrate when brought to the surface. This creature too may necessitate the creation of a new phylum. Once again, we see an extreme environment producing creatures which we never imagined, for these organisms represent a radically different form of metabolism than ones that have access to sunlight where there is a dependence on the oxygen/carbon dioxide cycle of photosynthesis. Here in the icy abyss, under enormous pressures of thousands of pounds per square inch, these geothermal vents have created small islands of life. The temperatures in the vents themselves are so extremely hot that they melt thermal probes from the submersible, but vast quantities of frigid, surrounding water create a zone in which life can, not only survive, but thrive. The question is how there can be life where there is no sunlight. The remarkable answer is that these organisms have evolved a system which is based on the metabolites of sulfur compounds. Biologists have, for a number of decades, known about sulfur bacteria, but no one ever dreamed that such complex eco-systems, as those of the volcanic funes, existed. Nature constantly surprises us with its inventiveness and tenacity.
In a previous article I wrote about a life form which I find amazing, astonishing, and alien—Gromia oviformis. Imagine an amoeboid creature with a shell, that extends an intricate net of pseudopodial filaments around itself and which has protoplasm streaming in both directions on the filaments like a two-lane highway. Further imagine that this net can extend over 20 times the size of the shell—now that is a strange creature! One of my friends is convinced that I am the Dr. Frankenstein of micro-organisms—ah, if only it were true!—and he once remarked, “Every time I come over here, you show me something stranger than the time before, but Gromia is the most alien creature I’ve ever seen.” Since then I think he’s been rather disappointed that I haven’t been able to come up with something more alien than Gromia—but, I’m working on it! Again if you want the details, I’ll let you check the article.
In the old days, when things were simple, especially taxonomically, Gromia was associated with the amoebae, as were, the giant Pelomyxa, the Radiolarians, the Acantharians, the Heliozoans, and the flagellated amoeboid critters, but now under the new kingdom of Protoctista, they’re all divided up into other phyla and all of this reorganization shoots down the popular 19th Century theory that all life evolved from some ultra-primitive amoeboid-like creature. Gertrude Stein said: “A rose is a rose is a rose. The world began with a rose” and in those earlier, simpler days, simple 19th Century souls, such as myself, could believe that “An amoeba is an amoeba is an amoeba. The world began with an amoeba.”
The taxonomists do have some very good reasons for all this juggling, renaming, and neologizing, but, at times, they forget a central Aristotelian maxim: “All things in moderation.” At this point, the kingdom Protoctista is a giant catchall for a large number of tenuously related organisms that nobody knows quite what to do with and, as more unusual micro-beasties are discovered, undoubtedly many of them will end up in the temporary holding tank of Protoctista. The important thing for us is that this kingdom provides example after example of organisms which are almost unimaginably weird, as well as fascinating.
So, let’s look at a few more examples, beginning with a few of those organisms that used to get lumped together as amoebae. First the famous Pelomyxa, the “giant amoeba’, the most well-known species of which is palustris and it is a collection of anomalies. Pelomyxa belongs to the phylum Karyoblastea and, although, over the years, twenty-some species have been described, most investigators now believe that there is just the one species P. palustris. Specimens can vary in size from less than 100 microns to more than 5,000 microns! If we found a mammal which, in its adult stage, could vary in size by a factor of 50, I suspect that we would be sorely tempted to create a number of different species designations. These creatures have symbiotic bacteria living within them and Pelomyxa are voracious algae feeders, in fact, virtual eating-machines. An interesting historical curiosity for me is the fact that the first discovery of Pelomyxa was in Wyoming by Leidy in 1879.
Pelomyxa has a complex life cycle and, as a consequence, varies considerably in size, shape, and general appearance in different stages. It has a highly vacuolated protoplasm and is multinucleate. There are a few reports of a single nucleus, but in its advanced developmental stages, the number of nuclei ranges from several hundred to 2,000!
In its adult stage, it is mono-pseudopodial, that is, it has one single, large “foot”,whereas, most amoebae have multiple pseudopodia often flowing at several places at once and sometimes in more than one direction. Pelomyxa has a uroid or a sort of rounded tail-like structure which often appears to be lumpy and is probably sticky, since all sorts of debris accumulates on its surface, giving it this lumpy appearance. Certainly, it is clear that this is no garden variety amoeba and it is thus understandable why “The Classifiers of All Things Living”—if I were running the planet, that would be my official title for taxonomists—want to place these creatures in a special and distinct category.
“Ordinary” amoebas are amazing enough, but sometimes when you’re browsing leisurely through a slide at high magnification, you happen upon some very small amoeboid-type organisms which are quite interesting. When they’re not “resting”, their pseudopodial movement is quite brisk and as you observe them, you suddenly notice something very odd and you may very well not believe your eyes at first. Something flicked into view that looked like a flagellum and, as you continue watching, you see it again—an amoeba with a flagellum! You didn’t learn about these in High School biology. And there are indeed a number of amoeboid-like creatures that sport flagella [O.K. Dr. Margulis—undulipodia (ugliopodia!)]. In significant respects, the more we learn about the biological world, the less predictable it becomes. The Scottish philosopher, David Hume, argued that the examination of Nature provides much more incentive for accepting polytheism than monotheism. Think about the duckbilled platypus—surely only a committee could come up with such a creature.
While we’re on the subject of amoebae, consider this—an amoeba that lives in a spherical casing punctuated by multiple holes, possessing spines on the casing and the sphere sitting atop a stalk. This is a lovely, little freshwater organism known as Clathrulina and, once seen, always fondly re-encountered.
The problem is that once we attach a label to a group of organisms, we tend to treat one (or a few) as prototypical, thus when someone mentions an amoeba, we think of a tiny, colorless, shapeless blob. The term “amoeba” became a kind of super category which embraced not only the ones I’ve mentioned above, but Radiolarians, Foraminiferans, and Acantharians which groups contain some of the most architecturally elegant creations of Nature. So, it’s no wonder that there’s confusion when someone is talking about a kind of free-floating amoeba that has filopodia which extend out through the tiny openings of a lovely glass sphere ornamented with spines and intricate projections, and there you are, thinking about a tiny, colorless blob.
As a consequence, one has to have a certain sympathy for those compulsive orderers, the taxonomists, who want to get everything straightened out and sorted into nice neat, unambiguous groupings. However, in the end, deep down, even they know that such an enterprise is a dream or, perhaps better put, an endless enterprise, since Nature continues to spring new surprises on us.
In the meantime, read, browse, explore odd niches looking for bizarre and fascinating creatures. If you don’t, I’ll write another article about them.
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