Onychophoran (Velvet Worm) II
Bill Long 7/14/06
Let me begin with a mindless two-line poem that I just made up, before getting into a few more things about onychophorans.
O velvet worm, though thou art smooth,
Thou art the one that made me lose.
I think, and you will probably concur with me, that I need to spend quite a bit more time on poetry before I submit one of mine to the New Yorker.
A Word on Origins and Terminology
One of the important tasks for evolutionary biologists (who will be around as long as "Creation Science" fundamentalists don't hijack science education) is to try to locate the phenomena of nature in a developmental chart. Thus, there has been a great deal of debate whether onychophorans are linked in some way to Aysheaia pedunculata from the Middle Cambrian Burgess shale (this is a very long time ago) or to the Middle Pennsylvanian (having nothing to do with Harrisburg) Mazon Creek Helenodora inopinata. All of this, however, is "highly speculative." Thus, we don't know how to relate onychophorans to more inclusive categories of classification.
The same problem exists with less inclusive categories. Onychophoran is the phylum name, and two families, the Peripatopsidae and the Peripatidae, are now recognized. It is assumed that these are sister taxa but whether they evolved from a common ancestor is up in the air. And then, since they are "remarkably similar" over a wide distribution (existing everywhere except North America, Europe and Antartica), identification at the species level is very difficult. Like Melchizedek they seem to have no mother or father but continue as insects for ever (a poor paraphrase of Hebrews 7, as I recall).
But I was really taken by descriptions of their reproductive activities. Reproduction takes place in what might call the "normal" way and in a very "abnormal" way. First, the normal. A male may deposit packets of sperm (spermatophores) directly into the genital opening of the female. So far so clear. But he may also place his spermatophores anywhere on the body of the female he wishes. What then happens? Apparently the skin tissue of the female collapses where the spermatophores have been placed, and the sperm rushes in to the female's body and finds its way to the ovaries to fertilize the eggs. Sperm also might be "stored" in the female body for several months. Never know when you might need a release of the stuff, you know.
I wonder if the word "collapse," which I took from the encyclopedia, is a "loaded" term. Males like the notion of females collapsing when their sperm is around, but is that what really happens? Could one also have described the process as the sperm "migrating" or "seeping through" the cuticle or outside skin of the female? I don't know, and when I see an evolutionary biologist I may just ask him or her whether female skin collapses under the weight of male onychophoran sperm. I think I might be arrested, however, if I led off with that question.
There is one more method, however, of reproduction, which is even more fascinating than depositing the sperm wherever the guy wants it. In some Australian varieties, the males apparently place their spermatophores on their heads "like tiny trophies in readiness to present them to a female." Indeed, some of the onychophorans have developed rather elaborate head structures, including spikes, spines, pits and depressions either to hold the sperm or assist in transferring it to the female.
Let's just stop there for a moment. We can see from this one example how much effort goes into getting ready for sexual encounter and reproduction. The sperm is placed anywhere on the female and it seeps in. Or, the sperm is displayed on the male's head, like a trophy, to attract the female, I suppose. I wonder sometimes if we have progressed evolutionarily beyond the simple mating calls of the onychophorans. And, maybe someone else will say, 'Hm....why should we?'
I have been trying for years to come to grips with my fascination with understanding what things are called by people. I have tentatively concluded that this is simply my Adamic self coming out. For doesn't the story of Genesis tell us that after the creation of man and woman, God brought every living creature to the man to see what he would call it, and whatever he called it, that was its name? (Gen 2:19). I think I am fascinated with this calling process, as if understanding how we name things tells us something not only about the things in the universe but about ourselves as the namers.
Just think. All of this because I got a word wrong. What if I took the time to do this for words I spelled correctly? Well, we could start with xebec (though I won't...).
Copyright © 2004-2008 Wiliam R. Long