Myriapods are arthropods (animals with jointed legs) that have numerous pairs of legs. The original Greek word means “10,000 feet”. The number of legs in adult myriapods varies according to species and ranges from nine pairs to nearly 200. All species are terrestrial and can generally be found in the soil, in leaf litter and under rocks and rotting wood. Many species possess specialized glands that secrete foul-tasting compounds. This large group is divided into four classes: Diplopoda, Chilopoda, Pauropoda and Symphyla.
This class is the largest, with more than 10,000 known species, most of them living in warm climates, and includes millipedes. Millipedes are arthropods that have two pairs of legs per segment as adults, hence the name diplopod or “double legs.” Most millipedes feed on decaying organic matter, although some will eat fungi and others are carnivorous.
Centipedes make up the second largest class, with over 2,500 species. They have only one pair of legs per segment. Unlike millipedes, nearly all centipedes are predators, although some will eat plant matter. The first pair of appendages on the trunk is modified into a pair of claws with poison glands, which centipedes use to capture prey (usually other arthropods). Some centipedes, when disturbed or handled by a human, can inflict a painful bite, but there are no reported cases of human fatalities from such bites. The biggest centipedes grow to a length of 30 cm.
Symphylans resemble centipedes, but are translucent and measure 2 to 8 mm long. They usually have 12 pairs of legs, sometimes 11.
These tiny arthropods vaguely resemble centipedes. They are less than 2 mm long. They have rather short, sometimes flattened bodies, and possess nine pairs of legs (rarely ten).