Wilderness Underfoot: Surviving, step by step, through eons

StoryImage( ‘/Images/Story//Auto-img-111401671720155.jpg’, ”, ‘A living fossil – Scutigera, the common house centipede, is a holdover from the ancient Illinois coal forests. After 300 million years, it has changed so little it is virtually identical to its fossil ancestors!’);
StoryImage( ‘/Images/Story//Auto-img-111401677520155.jpg’, ”, ”);
StoryImage( ‘/Images/Story//Auto-img-111401679720155.jpg’, ”, ‘A 300-million-year old Illinois millipede–Myriacanther-pestes was 10 inches long, with spiked segments.’);
StoryImage( ‘/Images/Story//Auto-img-111401682123354.jpg’, ”, ”);

The many-legged millipedes and centipedes preceded almost every other group of animals in taking the first steps on land…

The earliest evidence of an air-breathing land animal was discovered two years ago by an amateur fossil hunter in Scotland. His amazing find was a little millipede, now named Pneumodesmus newmani. It lived about 428 million years ago, in the Silurian Period.

Scientists believe that millipedes and centipedes quickly followed the scorpions in colonizing the land. They evolved from segmented worms that crawled about the ocean floor on rows of bristly limbs known as “parapodia” – it isn’t difficult to imagine how they eventually gained their land legs. To breathe air, they acquired a system of tracheal tubes that were connected to tiny holes, or “spiracles,” on the side of each segment. These air-breathing organs aren’t found on underwater creatures.

Millipede means “thousand legs,” while centipede means “hundred legs.” The true number of legs varies in both of these orders, but it actually never exceeds 200 pairs.

Although they belong to the same class of animals, and they are similar in appearance, there are important differences between millipedes and centipedes.

The millipedes have cylindrical bodies. They tend to be herbaceous – that is, plant eaters. These creatures are important decomposers. Many of them rely on foul-tasting, often toxic chemicals as a defense against predators.

The centipedes have flattened bodies. They tend to be aggressive hunters, eating everything from microorganisms to vertebrate animals. For killing, they rely on poisonous fangs that evolved on their first pair of legs. One recent video documentary showed a large tropical centipede chasing a lizard up a tall tree; when the lizard finally reached the end of its branch, it threw itself off the tree to avoid the centipede’s highly venomous bite!

From the April 20-26, 2005 issue

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