Things that don't belong where
As I have remarked before, Nature is full of little surprises
and clearly has no concern for our expectations regarding how
things should be ordered and arranged. Often the microscopist
comes across bits and pieces of things that seem out of place in
terms of our ordinary ways of thinking about the world. Everyone
knows that there are two kinds of sponges, the ones that come
from the sea and ones that come from DuPont. Surprisingly enough,
there are also a few species of freshwater sponges and if you
live in the right area and are persistent enough, you can collect
some. The morphology and physiology of sponges is quite
interesting, but they're not very exciting to watch as they don't
do much. If you don't find any in your area, you can order a
preserved sample from a biological supply house and familiarize
yourself with their structure. The quest for freshwater sponges
can be frustrating. In one year, they will be abundant in a
particular lake and then the next year, you won't be able to find
any at all.
Another thing that we all know is that jellyfish are marine animals, right? Well, almost. There is a very small freshwater jellyfish, about 1/2 inch in diameter, with the impressive name Craspedacusta sowerbyi. I take it that the species is named for someone named Sowerby who found this little creature where it shouldn't benamely in freshwater. If I had found it, I would have named it after myself tooafter all, imagine a freshwater jellyfish! Now, admittedly, this creature is not as impressive as the giant arctic Lion's Mane jellyfish or the Portuguese Man-of-War, but the fact is, one just doesn't expect even "little" freshwater jellyfish. It's like having a freshwater dolphin. Well, there is such a creature in the Amazon. And then there are sea snakes (very venomous!). Freshwater seals in Lake Baikal! Hey, come on, Mother Nature, get a grip. This is getting too complicated for us ordinary mortals; no wonder we get confused.
You are all familiar with Limulus, the horseshoe crab, a kind of living fossil. Well, there's a small (about 2 inches long) freshwater creature that rather reminds me of the horseshoe crab and both of them remind me of trilobites. This freshwater beastie is called a tadpole shrimp (Triops), although I don't quite know why; it doesn't in the least remind me of a tadpole. In this area, it is to be found in the early spring when there is runoff from the mountain snow into temporary ponds. Sometimes in one of those ponds, not more that 100 feet across, one will find thousands of tadpole shrimp often along with fairy shrimp (Chirocephalus), both of which are in a phylum called Eubranchiopoda along with the clam shrimps. This is another one of those groupings that I call "warehouse phyla"here's where one stores stuff that you don't know quite else what to do with.
I can run a small net through the water and literally fill it with these two organisms in a few seconds. Sometimes several years go by when there isn't enough water to fill these little ponds, but when there is, life explodes. The eggs of these wondrous creatures are heat resistant, drought resistant, cold resistant and generally astonishing with regard to their repertoire of survival tactics down there in the mud. Given a bit of water, a few nutrients, and food reproduction begins at an incredible rate. The race to lay new eggs is on, for the pond may only last a matter of a week or two. These creatures appear so primordial that I often wonder how they came to inhabit these small places located at over 7,000 feet above sea level.
Sometimes, when I'm scanning a slide of a pond sample, I come across a butterfly scale. Even though it's happened numerous times, I'm always surprised and the same is true for fish scales. They have every right to be there; there's a perfectly natural explanation for their presence, but I never quite expect them. There is one lovely beaver pond hidden away in a little valley in the mountains which I have kept quite secret. I have shown only my wife and two of my friends its location. It is fed by an icy cold spring which forms a small stream which then meanders several hundred yards, spreads out and flows into this magnificent pond. On the one side is a steep, rocky hill covered with wildflowers, down which I climb to the edge of the pond. On the other three sides, there are tall willow bushes, pine trees, and quaking aspen trees which in the fall turn brilliant yellow and muted orange. In the spring and summer, there is the almost constant drone of insects; everything from the high-pitched whine of kamikaze mosquitos to the low hum of the aerodynamically improbable bumblebees. In addition, there are the extremely annoying deerflies, which have a quite unpleasant bite, but to make up for them, there are the elegant damselflies darning the air and the B-52 bombers of the insect world, the amazing dragonflies.
At the east end of the pond are the logs of a beaver dam where the water flows down to nourish several other ponds deeper in the forest. About 100 feet from the dam, down into the forest, I had the great good luck, one beautiful summer afternoon, to discover a hummingbird nest. The nest looked like a thimble made of twigs and dried grass. There was at least one egg, perhaps two, but as soon as I approached the nest I backed off again, because, out of the corner of my eye, I saw the mother hovering in great agitation. Talk about an aerodynamic improbability! With all out ingenuity and technological know-how, the hummingbird, just in terms of sheer maneuverability, surpasses anything we can produce. Around our house, we see hummingbirds from time to time in the summer, sampling the nectar of our fuchsias. Hummingbirds always make me think of hummingbird moths which occasionally, in the early evening, we will see hovering in one of our flower beds.
A video clip by Ken Jones prepared for the web by Maurice Smith of the organism Plumatella. From an archived Micscape article 'Pond Fairies'.
But back to the beaver pond. This special place is the only location where I have ever collected active colonies of the bryozoan, Plumatella. They were growing on the submerged parts of logs in the pond and with the careful use of a sharp pocket knife, I was able to slice some thin layers of bark on which the Plumatella were growing. I transported these to my lab and transferred them to large culture dishes and by keeping the water very clean and feeding them regularly, I managed to keep them going for about 3 months. I find the bryozoan statoblasts ( a sort of egg-cyst) in ponds and lakes all over the high plains and mountains, but as hard as I search, I don't find the colonies. I did once manage to get some statoblasts to develop and I carefully fed them every 2 or 3 days. Again they lasted for about 3 months. It was a fair amount of work to keep the water clean and feed them just the sorts of organisms they liked, but it was well worth it. To watch those elegant, feathery tentacles glide out of their tubes and begin to feed was more than sufficient reward. The reason I am writing here about bryozoans is that they too seem out of place in high freshwater lakes and ponds. When I think of bryozoa, I think of the sea. Only a very few species of bryozoan live in freshwater, but in the oceans, there is enormous variety and quantity. One can hardly walk along a beach upon which kelp has washed up without discovering some Mebranipora (or sea mat) colonies on those large algae. On wharf pilings, on mussel shells, on tunicates, on sponges, everywhereone finds bryozoa in the sea. But in freshwater, they are a splendid oddity. I live in the state of Wyoming which is very large and there is a species of bryozoan which has been reported from Uinta county in western Wyoming and no place else in the worldhow's that for having an out-of-place creature in an out-of-the-way place? (Even many Americans aren't sure where Wyoming is.)
Sometimes when working in my lab, I dry my watch glasses with facial tissue rather than the more expensive "lint free" wipes from supply companies, so I frequently come across fibers when examining samples in such dishes. Also, dust mites are constantly crawling into my culture dishes where they don't belong. However, I can't really complain, since they don't last too long in that environment and as they decay they end up providing food for the other beasties in the dish.
I mentioned Lake Baikal and the freshwater seals earlier. Baikal is a world of its own, a distinct realm which must be preserved. It is badly polluted especially from pulp mills and the Russian economy can manage only minimal efforts to preserve this unique habitat. Baikal contains one-fifth of the fresh water on the planet! In ancient times, however, it was connected to the sea and then eventually closed off, creating one of the most remarkable evolutionary laboratories in the world and yet it has barely been explored. Here we find creatures, from mammals to protists, that exist nowhere else. There are remarkable sponges, several feet highlike marine sponges, not the paltry pale growth of the usual freshwater Spongilla. There are also probably more species of Suctoria, those strange tentacled relatives of the ciliates, than any other place in the world. Here is an enormous environment where all kinds of things that "don't belong" show up. I just hope that we as human beings who share the world with all these other life forms will find more and better ways to preserve their existence.
What originally prompted me to write this essay was an experience of mine last summer. I had collected some samples in a ditch alongside a country road. I happen to remember exactly were it was, because it was on the south side of a road that leads up to a little country school in a rural area with the wonderful name of Harmony. The ditch was quite long, perhaps ten feet wide and three or four feet deep. Further down I saw some ducks swimming. The water was rich with algae, no doubt due to the nutrients provided by the feces of the waterfowl. Having, in the last two or three years, developed an increasing interest in local algae, I was especially anxious to examine these samples. That afternoon as I was revelling in the varieties of algae, I discovered a freshwater foram!
Now, to my best knowledge, there are no freshwater forams. There are shelled amoebae, such as Arcella and Difflugia; there are heliozoans; there are even proto-foraminifera, such as, Gromia; but your classic, spiral, mini-ammonite shaped foramNO! But I had found one and my collecting jars were clean and unused, so it couldn't have come from an old marine culture I had. Here was something that really didn't belong where it was. It was only the shell, no organism, and I spent the rest of the afternoon sorting through subsample after subsample looking for other specimens, but, naturally, there was only the one. I put it in a small vial of alcohol.
The lakes west of Laramie are on a migratory path for Canadian geese, pelicans, blue heron, ducks and many smaller birds. I suspect one of them was wading around in the mud of an estuary or marine bay and got a foram stuck to its foot and brought it all this way just to fool me. If not, I have a very nice specimen of a freshwater foram.
Comments to the author Comments to the author sent via our contacts page quoting page url plus : ('rhowey','')">Richard Howey welcomed.
Editor's note: The author's other articles on-line can be found by typing in 'Howey' in the search engine of the Article Library, link below.
Also see Gen-Yu Sasaki's article on the freshwater jellyfish.
Published in the April 1999 edition of Micscape Magazine.
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