Invertebrate

Millipedes

Note: The millipedes that we use in our classes are not long lived and we will at times have African species and at other times have South American species, therefore the information listed is general in nature, not species specific.

CLASSIFICATION
Both Millipedes and Centipedes belong to the Phylum Arthropoda—meaning “Joint legged.” Arthropods are segmented animals with jointed appendages with stiff exoskeletons made of chitin. Members of this group include crabs, lobsters, barnacles, insects and spiders. Millipedes and Centipedes, all though related, belong to two separate classes.
Class: Chilopoda (the Centipedes)
Class: Diplopoda (the Millipedes)
The main differences that exist between millipedes and centipedes will be outlined in the following information. Probably the most obvious difference people note is that millipedes have two pairs of legs on most segments of their bodies, as opposed to one pair found on centipedes.

RANGE
Millipedes and Centipedes are distributed worldwide, and are especially prevalent in the tropics.

HABITAT
Most species prefer damp surroundings, such as underneath leaf litter, under bark, animal dung or rotting logs.

SIZE
Sizes vary greatly depending on species. There are believed to be at least 3000 species of centipedes worldwide, of which 100 can be found in the U.S. They range in size from a few millimeters to the largest known species: Scolopendra gigantea of Central America, which can reach 10 ½ inches long.
Approximately 8000 species of millipedes are thought to exist. Millipedes range in size from soft-bodied species less than 1/10 of an inch long, to heavily armored forms exceeding 8 inches in length.

LIFE EXPECTANCY
Average around 1 year

REPRODUCTION
Reproduction in most centipedes does not involve copulation. Males will typically deposit a sperm packet on the ground which will be collected by the females and stored for later fertilization of the egg. Females of some species make underground nurseries to contain their eggs and will guard them until they hatch.
Millipedes, in contrast to centipedes, do have physical contact during mating and may remain linked for several hours. Males and females embrace, lower surface to lower surface, with the genital openings found in the third body segment and fertilization takes place internally in the female. Depending on the species, 10 to 300 eggs may be laid. Some millipedes coat each egg with soil and excrement, possibly as a camouflage from predation. Some species build elaborate nests, while others may just deposit their eggs in a crevice in the earth.
The size of populations, especially in the millipedes is often weather and nutrient dependent. If the soil is moist and nutrient rich, numbers will go up. Large migrations of millipedes have been reported in the past, and are usually associated with dry periods which follow wet, moist periods.

DIET
Centipedes are fast moving, limber, flat bodied predators that make a living hunting other creatures. They generally have powerful jaws and painful bites that are used in the catching of their prey. Centipedes will prey on a wide variety of insects, including cockroaches and beetles, and earthworms. Larger Central American varieties have been known to eat lizards and mice.
Millipedes lack the powerful jaws found in centipedes, and are almost completely herbivorous in nature. Millipedes focus their feeding on dead and decaying organic matter and /or humus. They will also feed on vegetative matter and some species have at times become problematic during wet, moist conditions as pests feeding in farmers crops.

BEHAVIOR
Centipedes are built for fast movement. Most species have simple eyes and are sensitive to light. Many are nocturnal in nature, spending most of their time avoiding light while hunting for their prey. Experiments have shown that even in centipedes that have had their eyes covered, they can still sense light and will avoid it whenever possible. It is believed that this avoidance of light is also a way of avoiding predation. Some species are phosphorescent and are known to leave glowing trails that are capable of stinging a pursuer. The main line of defense in most Centipedes is their powerful jaws, which are capable of inflicting a highly painful and sometimes lethal bite. Despite their unappetizing appearance and traits, some South American natives eat them, after carefully removing their poisonous claws.
Millipedes, in contrast to the fast-moving centipedes, are built for pushing their way powerfully through soil or vegetation. They lack the powerful jaws found in the centipedes and so must rely on other methods of defense against predators. Pill-millipedes curl up into small balls with their hard outer covering facing outward. Some tropical species are the size of golf balls. The usual defense of millipedes is a row of poison glands that run down each side of the body. The secretion from these glands may be a range of colors from reds to yellows to browns, and generally smell of excrement or chlorine. Iodine, quinine and compounds of cyanide are often found in these secretions. These secretions are highly toxic and can make them unpleasant to handle. One Mexican species is ground up with various plants as an arrow poison. Most species secrete their venom by having it ooze out of pores along the body, however some spray to blind a molester and discharge onto human skin on cause it to blacken and peel. Cyanide gases given off by some millipedes can be deadly to those unlucky enough to breath them in high concentrations.

POINTS OF INTEREST
Millipedes are not born with their full compliment of segments and legs. Typically they hatch out with as few as three segments and new segments are added with each successive molt. Millipedes often build silken cocoons in which they molt or shed their skins. The shed is often consumed afterward to replenish lost nutrients. Just after shedding is the most vulnerable time for the animals, since it takes time for the new skin to harden.
Millipedes differ from centipedes in a variety of ways, as discussed previously in this write-up. Other ways in which they differ include: Millipedes have only short antennae, unlike centipedes which have long antennae. Some species of millipedes have no eyes, and although most segments have two pairs of legs, the first four segments have only one pair.
There are some species of millipedes that are luminous. One species in the Sequoia forests of California which is aptly named Luminodesmus sequoiae, is blind and its light shines continuously from the time of hatching. It is believed that the luminous glow is a warning to predators, since this species is one of the more poisonous, cyanide producing species.

STATUS
Common and widespread throughout the world.

REFERENCES
Grzimek’s Animal Encyclopedia. Dr. Dr. h.c. Bernard Grzimek, Editor-in-Chief. 1975
The International Wildlife Encyclopedia. Dr. Maurice Burton and Robert Burton. General Editors Volume 11, 1969
Readers Digest North American Wildlife. Susan J. Wernert, Editor, 1982