Millipedes of Petroglyph
A Fascinating Creature
Petroglyph National Monument is unique in many ways, but one of its most striking attributes is the seventeen-mile long volcanic escarpment. In addition to having thousands of petroglyph's on the basalt boulders, the escarpment is home to many plants and animals that may not usually be found this far north in the Chihuahuan Desert. The boulders strewn across the escarpment allow moisture and heat to be concentrated. This gives plants and animals the slight edge they need to be able to survive. One such animal is the millipede. Millipedes are known to exist in many different habitats from rainforests to sub-alpine mountaintops to deserts. The millipedes that live in these diverse habitats have adapted in order to survive the elements. Some have developed mechanisms to keep from freezing, to keep from being eaten or to keep from drying out in the heat. In whatever habitat they occupy, millipedes are fascinating creatures that have a long history and are an important member of the ecosystem.
Desert and Slate Millipedes
There are two species of millipedes at Petroglyph National Monument, the Desert Millipede (Orthoporus ornatus) and the Slate Millipede (Comanchelus chihuanus). These two species can be easily distinguished by size and color. Desert millipedes can grow to about 8 inches long and are a chocolate brown color. Slate millipedes are only about 3 inches long and are a dark gray (almost black) color.
What is a Millipede?
Millipedes are arthropods, not insects or bugs. An insect typically has three body segments and six legs. A millipede has many body segments and two pairs of legs per segment. If you want to know how many legs a millipede has, count the number of body segments and multiply by four.
Petroglyph's offer opportunities to think about how human inhabitants interacted with nature. For instance, spiral petroglyph's are commonly found in the monument. Some American Indians think they may represent a desert millipede in its coiled, defense posture while others think they may represent water. Since millipedes are most active during the rainy season, perhaps the connection is water. As you view the images, consider how they fit into the landscape and how they may have and continue to be important in American Indian culture.
Survival in the Desert
There are few ways for animals, insects and arthropods to survive in desert conditions. They can evade or avoid climatic conditions, they can find water or their bodies can adapt. Millipedes take advantage of all three of these strategies and if successful, can live up to 10 years.
Watch your step
Millipedes are fun to watch. Keep in mind, millipedes may be harmless, but they are wild creatures and should be treated with respect. Millipedes do not bite, however, they do have natural defensive actions. If a millipede is disturbed or threatened it curls itself into a spiral. It may also secrete a liquid toxin from its secretory glands on the side of its body. This mildly toxic secretion is meant to discourage any natural predators from eating the millipede. Feel free to look at millipedes as they go about their lives, but please do not touch. Some humans may experience a mild to severe allergic reaction to the millipedes' toxic secretion.
Millipede or Centipede - Can you tell the difference?
Millipedes should not be confused with centipedes (Scolopendra Spp.). Centipedes have a brown and yellowish, flattened body with one pair of elongated legs per body segment. Do you remember how many legs per body segment a millipede has? Centipedes have one pair of longer antenna, millipedes have one pair of shorter antenna.
Desert Millipede (Orthoporus ornatus)
Centipede (Scolopendra Spp.)