Sitting in our living room one evening, I looked up to see a six-inch-long, flattened, brown critter with many legs - a centipede -swarming across the carpet towards me. I ran to the kitchen to get a glass to catch it with. Trapped under the glass, the centipede raced in a circle, its 40 or so legs rippling in perfect coordination. Richard and I watched it, fascinated and repelled.

Centipedes, named for the erroneous belief that they have one hundred feet, are neither cute nor cuddly. Creepy partly because of their nocturnal habits, when exposed to light, centipedes run away like guilty teenagers. They also pack a nasty and painful bite. But centipedes are fascinating, and important to the web of desert life.

Centipedes are arthropods - critters with external, jointed skeletons like insects, or shrimp, and belong to their own class, Chilopoda, Greek for "thousand feet." Actually, centipedes rarely have more than 60 or 70 feet, and the same number of legs. Although often called insects, centipedes possess too many legs: Insects have six or fewer; centipedes never fewer than 30. Also, insect bodies are divided into three very different segments; centipede bodies are comprised of a tiny head and many similar segments, each sporting one pair of legs.

Despite poor vision, centipedes are hunters. They find their prey with keen s

enses of smell and touch, and then run towards it, propelled swiftly on gracefully flowing multiple legs. They administer the coup de grace by clasping the prey with a pair of sickle-shaped, venom-dispensing pincers at the end of their first pair of legs. In humans, such a "bite" is painful, but not fatal. Smaller centipedes make good housemates, eating spiders and all manner of insects, including cockroaches, clothes moths, and house flies.

Unlike most arthropods, centipedes do not possess an impermeable wax "shell" to protect them from dehydration. They therefore hunt in the cooler, more humid night, spending the day buried under rocks or wood. During the hottest and driest parts of the year, centipedes burrow into the soil and become dormant until the rains again call them forth to hunt at night.

The centipede that swarmed across our living room was a giant desert centipede. North American's largest, these centipedes grow up to 9 inches long, and dine on small lizards, geckos, toads, and rodents. They are found only in the Chihuahuan and Sonoran deserts here in the southern Southwest.

As we watched, horrified, the captive centipede began attacking and pinching itself in a frenzy, and finally lay quite still. Half afraid that we had killed it, I took it carefully outside in the glass, and put in on the ground by the back fence. To my great relief, it ran swiftly away, to live what I hope was a long and very centipedal life.