Difference Between Millipedes And Centipedes
Scoop up a jar of pond water and you may see an abundance of scuds—tiny crustaceans that whir through the water on an abundance of legs. Some 450 million years ago, just such a creature may have spawned one of the first animals to walk on land—a myriapod, or “many-legged” one. This first, primitive myriapod eventually disappeared. But before it did, it gave rise to two related classes of invertebrates—class Chilopoda, the centipedes, or “hundred-legged” ones; and class Diplopoda, the millipedes, or “thousand-legged” ones.
Today millipedes and centipedes are abundant wherever there are dark, damp places to hide. They belong to the great phylum Arthropoda, alongside their cousins, the crustaceans, insects, and arachnids. Like other crustaceans, millipedes and centipedes have segmented bodies covered with a stiff covering, or exoskeleton. Like insects, they breathe through holes, called spiracles, in this covering. But unlike insects, millipedes and centipedes cannot close their spiracles to prevent water loss. As a result, they dry out easily. This is why you are most likely to find them in damp, dark places such as the underside of logs.
When it comes to distinguishing centipedes from millipedes, many people are understandably confused. Both look similarly bizarre, with wormlike bodies, insectlike heads, and an astonishing number of legs. Despite these mutual oddities, centipedes and millipedes could hardly be more different in temperament and lifestyle. The most important difference is the centipede’s poisonous bite.
Turn over any stone, log, or patch of damp leaves, and you are likely to find a few millipedes. Not appreciating the intrusion, they will likely glide away slowly and gracefully, on an undulating frill of delicate legs.
The millipedes common to North American gardens and woodlands are among some 8,000 species worldwide. The smallest burrow around plant roots, so tiny they can barely be seen. The largest include boldly colored tropical species that measure over 12 inches (30 centimeters) long.
Most millipedes feed on decaying plant matter. Others are garden pests, chewing away at roots or emerging at night to feed on leaves. A few large species gnaw at the bark of trees.
Somewhere in a damp basement, an unwary cockroach meets a gruesome end. Spearing the insect with deadly fangs, a centipede injects venom deep into its victim’s body.
The common house centipede, Scutigera coleoptrata, is one of about 3,000 species of centipede found in temperate and tropical regions around the world. The largest may be the highly poisonous, 10-inch (25-centimeter)-long Scolopendra gigantea of Central America. The tiniest include the harmless, threadlike centipedes found in garden soil. All are quick and aggressive predators, able to catch insects slightly larger than themselves. Seldom deadly to humans, the medium-sized centipedes of North America can nonetheless deliver a painful bite. Fortunately, they are easy to recognize.