Tim Smith, age 12, of So. Burnaby, B.C.,Canada.
How did the silverfish originate?
Home owners rate the silverfish as a sneaky little pest. Scientists regard him as an interesting creature with much to reveal about the origins of all insects. We cannot say when his family first appeared on the planet Earth. But recognizable fossils of his remote ancestors date back to the Triassic Period of some 230 million years ago. His family survived successfully while the mighty dinosaurs advanced and declined.
Tracing back the origins of the animals depends mainly on the fossils they left in the ground. Some species were better fossil makers than others. There was no problem in preserving the gigantic bones of the dinosaurs. But the tiny bodies of insects are fragile and prone to decay. Through the long ages, only a few specimens endured long enough to become fossils.
The earliest recognizable insect fossils date back to the Carboniferous Period, some 320 million years ago, when our coal deposits were swampy forests. They include extinct ancestors of modern roaches and dragonflies. Possibly ancient silverfish relatives were there also, but so far no evidence has been found.
The oldest known silverfish fossils date back some 230 million years to the early days of the dinosaurs. It is not likely that these were the earth's original silverfish and scientists use other methods to trace their possible family tree farther back into the dim past.
Experts in the story of life on earth suspect that the extinct ancestors of the insects were related to the extinct trilobites. Some 500 million years ago, the crusty trilobites of the ancient seas were the most advanced creatures on earth. Though now extinct, they are classed as jointed arthropods, as are the modern insects.
Some experts suspect that more recent relatives of the insects were segmented worms, also now extinct. After all, though the typical insect body is more advanced and specialized, it, too, is assembled in distinct segments. It is reasonable to suppose that butterflies, with their highly specialized life cycles originated much later than the silverfish and other more primitive species. The whiskery little silverfish is a wingless insect that grows by molting his scaly skin. In ancient days, his ancestors lived in the moist woods, where most of his relatives live to this day.
Strange to say, several silverfish species deserted their wild habitats and moved into human homes. Some types prefer cool moist surroundings; others prefer warm and dry conditions. But all silverfish prefer to live in dark crevices. When you spot a skinny little whiskery bug scuttling across the kitchen floor, you can be sure that his present brood originated in some secret crevice in the walls or the woodwork.