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COMMENTARY
March 20, 2010
Armoured worm
Fascinating little things, those plumulitid machaeridians; wee, body-armoured marine bristleworms. Until recently, we didn't know what they were -- whether ancestors of the molluscs, or of the barnacles, or of the echinoderms (sea stars and urchins), or of the annelid worms.We now guess this last, from a fossil specimen found in remote Moroccan mountains, with its soft body parts revealed intact; and from another, from a building site on Albert Street in downtown Ottawa -- in a rock, next to a gloriously crisp, though commonplace trilobite. Our Ottawa machaeridian -- a very rare and prize specimen for being so complete; usually we glimpse only fragments of their "calcitic sclerotomes" or armour plates -- is described in the current number of the journal, Palaeontology. We now take it for a common ancestor of the living annelids -- the "ringed ones" (ragworms, earthworms, leeches). In its heyday in the deep Palaeozoic, hundreds of millions of years ago, it had quite other morphological relations. As well as plumulitids, there were turrilepadids, and lepidocoleids. Or so I understand; I am not a professional palaeontologist. From the company they keep, in the fossil record, I gather the little guys fed on organic waste, including the ejecta of stylophorans and other common neighbours. They ambled about the sea floor on parapodia -- paired unjointed lateral outgrowths serving as multiple legs -- and if I am not mistaken, could roll up in a ball when threatened. We have jokes in Ottawa already -- "plus ça change," and so forth -- comparing the armoured worm to our contemporary politicians. But what intrigues me is the design -- and "design" is the only word for it -- of those armour plates. They work on the same principles as mediaeval body armour. That is to say, fixed plates slightly flexible in their curve; but from the angles in which they are rigid, they are subtly hinged and can move in relation to each other. For the apparel of knights, this required considerable craftsmanship. Producing the same effects on the millimetre scale of a plumulitid machaeridian takes us forward to the frontiers of nanotechnology -- or back 450 million years. "Plus ça change, plus c'est pareil." If the wee denizen of prehistoric Albert Street was indeed an early annelid -- in the world of DNA testing, morphological comparisons seem more and more naive -- he was wearing armour that his descendants would throw off. No later annelids carry calcitic armour. I find that quite striking. Not so, one of my Darwinist correspondents, who never finds anything striking, and will resent my use of the word "design"; though he uses it himself when he is not rolled up in his own psychic armour. We reach the vernal equinox today, and with glorious spring weather recently, I am reminded of the pleasure in throwing off a coat. My own winter garment did not "evolve" into an insignificant, vestigial coat, but rather, I hung it in the closet and just walked away. I am confident it will still be there, should I need to retrieve it. From what I can envision of the proceedings of DNA and RNA, nature is more likely to do something similar, rather than adapt by tiny increments to radical environmental change. The scientists play with the stuff. In for instance their beloved fruitflies, and lab rats, the most extraordinary transformations may suddenly appear, and disappear, from tweaking. One sometimes thinks almost any creature B could be metamorphosed from any creature A, by tweaking a series of genetic dials -- lungs to gills, arms to wings, whatever; toggle gleefully between hairs and feathers. And this we could do with precision and competence, perhaps, were we not men but gods or angels, with access to the original instruction "manual"; and maybe, the passwords to override standard speciation barriers. We are told obsessively by the materialists that we share 97 or 98 per cent of our genetic inheritance with the higher apes. This is impressive, as all misleading statistics are meant to be. But on that method of reckoning we also share more than 70 per cent with those fruitflies. By analogy, just a few more dials to tweak, to turn a fly into a man, or vice versa. Yet an impressive feat, all the same. That plumulitid machaeridian -- I want to call him Fred -- appears, in the long sequence of our planet's species, very much closer to the beginnings of multicellular life at the Cambrian "explosion" or "radiation," than he stands from us. Yet he is elaborate, and exquisitely designed. And if instead of being embedded in rocks, his kind had been casually crawling out from under them to the present day, we would take him for granted. "Looks like a bristleworm." I invite gentle reader to think long and hard about that. David Warren
© Ottawa Citizen
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