A massing of nematodes
Why
on Earth should Diana Wall or anybody else get excited about nematodes — round
worms that in most cases are too small to be seen with the unaided
eye?
Why should she be an enthusiastic booster of what is called nematology?
| What's inside a nematode: In this drawing of a typical nematode that lives in concert with a plant (that is, it's a parasite on the plant), the major parts are shown, left end to right: The pointy stylet (1) punctures plant cells for feeding. Then food moves through the esophagus (2), the median bulb (3), past a bundle of nerves (5) that connect with sensing devices in the head and tail, into more esophagus and past the esophageal glands (4), which are believed to release substances that help with digestion, into the digestive system (6) and eventually out the anus (11). There is a reproductive system; in this drawing of a female nematode, the ovaries (7) produce eggs (8), which are delivered through the vagina (12). The cuticle (10) is the nematode's grooved, flexible skin. The tail (9) is the part of the body between the anus and the tip of the nematode. The entire package lives in a wriggling body that can be so small that humans can't see it without magnification. (Graphic from "Nematode Basics" at the U.S. Agricultural Research Service's Nematode Laboratory.) |
People do not ordinarily have kind words (or any words at all) to say about nematodes. Nathan Augustus Cobb (1859-1932), a fellow who liked microscopes and was fascinated with little creatures, and who eventually became known as “the father of nematology in the United States,” has been quoted as saying:
The nematodes, poor beasts, do not furnish hides, horns, tallow, or wool; they are not fit for food, nor do they produce anything ornamental — in fact, when they are displayed in museums the public votes them hideous. (From A Natural History of Nematodes, by George O. Polinar [1983: Prentice Hall.])
And Sir Robert May, of England’s Oxford University, has complained that it’s not just the general public that is fickle about which species get its attention. There is abundant knowledge in the world about birds, he said at a 1988 meeting about biodiversity, but “little affection for nematodes. This is a hell of a way to run a business.”
Maybe it's because there are so many.
Perhaps nematodes
are worth getting excited about because there are so many of them. The
little round worms constitute Earth’s second largest phylum.
Nobody knows for sure how many species of nematodes there are in and on
the world, but estimates range from 500,000 to 100 million or more. Fewer
than 25,000 species have been described
by science.
 |
| Nathan Augustus Cobb was a dedicated nematode collector. This is one of his original microscope slides; he collected the specimen in 1890 while on a field trip in Australia. (USDA Nematode Collection) |
Even though most people are perfectly content to go about their daily lives without giving half a moment’s thought to nematodes, the soil beneath their feet is so full of the creatures that life would be quite different without them. That same Nathan Augustus Cobb wrote, in the U.S. Department of Agriculture’s annual yearbook for 1914:
. . . if all the matter in the universe except the nematodes were swept away, our world would still be dimly recognizable, and if, as disembodied spirits, we could then investigate it, we should find its mountains, hills, vales, rivers, lakes, and oceans represented by a film of nematodes. The location of towns would be decipherable, since for every massing of human beings there would be a corresponding massing of certain nematodes. Trees would still stand in ghostly rows representing our streets and highways. The location of the various plants and animals would still be decipherable, and, had we sufficient knowledge, in many cases even their species could be determined by an examination of their erstwhile nematode parasites.
But what are nematodes really like? Click here for details.