Hoffman, Richard L. Department of Recent Invertebrates, Virginia Museum of Natural History, Martinsville, Virginia.
Last reviewed:December 2019
- Classification and distribution
- Related Primary Literature
- Additional Reading
A class of tracheate, terrestrial, oviparous arthropods (millipeds), characterized by a compact head with a coalesced labrum, a pair of eight-segmented antennae, bisegmented mandibles (typically with a series of pectinate lamellae) and a subbuccal gnathochilarium (lower lip) composed of two pairs of embryonic maxillary elements. The diplopod (milliped) body (Figs. 1 and 2) is not differentiated into thoracic and abdominal regions. Instead, it is composed of a variable number of similar, subcylindrical units (segments). In most species, the components of these segments coalesce into rigid cylindrical units, with each being formed by the fusion of two embryonic somites into apparent segments, most of which carry two pairs of walking legs (which is the source of the class name, Diplopoda). Several of the anteriormost segments have only one pair of legs, with the second pair being reduced to vestigial elements. The body wall is chitinous; in most species, it is heavily impregnated with calcium carbonate. The anterior part of each segment typically telescopes into the preceding one and most millipeds are capable of coiling into a spiral—in some cases, a compact sphere with the head innermost—as a protective measure (Fig. 3). In the majority of species, each segment posterior to the fourth segment is provided with a pair of glands (ozadenes), which produce a variety of volatile defensive secretions. Gas exchange occurs through a system of profuse fine trachea that open through stigmata located on the sternal elements adjacent to the leg bases. The digestive system is typically a straight tube divided into esophageal, gastric and intestinal regions; no proventriculus (dilation of the foregut) is present. Excretion is through nephridial tubes located in the hemocoelic cavity and discharging into the hindgut. The anal opening is in the last segment and is closed by two tightly fitting anal valves (paraprocts). Water recovery is accomplished in the subterminal rectal region. See also: Arthropoda
The content above is only an excerpt.
for your institution. Subscribe
To learn more about subscribing to AccessScience, or to request a no-risk trial of this award-winning scientific reference for your institution, fill in your information and a member of our Sales Team will contact you as soon as possible.
to your librarian. Recommend
Let your librarian know about the award-winning gateway to the most trustworthy and accurate scientific information.
AccessScience provides the most accurate and trustworthy scientific information available.
Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students. Contributors include more than 10,000 highly qualified scientists and 46 Nobel Prize winners.
MORE THAN 8700 articles covering all major scientific disciplines and encompassing the McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Yearbook of Science & Technology
115,000-PLUS definitions from the McGraw-Hill Dictionary of Scientific and Technical Terms
3000 biographies of notable scientific figures
MORE THAN 19,000 downloadable images and animations illustrating key topics
ENGAGING VIDEOS highlighting the life and work of award-winning scientists
SUGGESTIONS FOR FURTHER STUDY and additional readings to guide students to deeper understanding and research
LINKS TO CITABLE LITERATURE help students expand their knowledge using primary sources of information