Millipedes are typically dark brown or black in color, although different species exhibit color differences. Their bodies are divided into segments, the number of which varies among the species. Most millipedes have between 25 to 100 segments. They have round heads with two antennae, two eyes and one mouth. Millipedes breathe through holes called spiracles located on their body segments. They range in size from less than one-tenth of an inch to more than nine inches in length.
Despite the name millipede, which translates to thousand legs, these arthropods do not actually have 1,000 legs. Most species have between 36 and 400 legs. They are arranged in pairs, one leg on either side of the body and most segments of the millipede's body have two pairs of legs, although the first few segments after the head may contain one pair per segment and the last two segments have no legs. A millipede's legs move in an undulating, or wavelike, pattern when they walk.
Millipedes prefer cool, moist environments and are often found under rocks and logs or in leaf litter or soil. You may also find them underneath tree bark. Most species feed on decaying plant matter. Its body secretes a chemical that moistens the plant matter and then the millipede scrapes the food up with its jaw. Millipedes will also feed on seedlings if decaying plant matter is not available. There are also a few millipede species that are carnivorous, which means they eat other animals.
Millipedes have several natural predators, which are animals that eat them. They include a variety of bird species along with shrews and badgers. Millipedes avoid being eaten by curling their bodies into a tight spiral. This protects their legs and underbellies, which are not protected by a hard exoskeleton. Most species release poisonous substances to irritate potential predators. These secretions are either liquid or gas and burn the exoskeleton of other species, or irritate their skin or eyes. While these poisons aren't deadly to humans, they may cause skin or eye irritation. If you've recently touched a millipede and your skin or eyes are itchy or burning, flush the area thoroughly with water.