HOME WEB NEWS IMAGES CLASSIFIEDS YELLOW PAGESPOLLS - SURVEYS WIKI COUNTRIES PHOTOS US UK INDIA
Cities Stocks Weather Movies Coupons Travel Blogs Health Horoscope Maps ASIA EUROPE Classifieds Yellow Pages
 1
|
Myriapoda is a subphylum of arthropods containing millipedes, centipedes and others. The group contains 13,000 species, all of which are terrestrial Ben Waggoner (1996-02-21). Introduction to the Myriapoda. University of California, Berkeley.. Although their name suggests they have myriad (10,000) legs, myriapods range from having over 750 legs (Illacme plenipes) Paul E. Marek & Jason E. Bond (2006-06-08). Biodiversity hotspots: rediscovery of the world\'s leggiest animal. Nature 441: 707. doi:10.1038/441707a. to having fewer than ten legs. They have a single pair of antennae and simple eyes.
Myriapods are most abundant in moist forests, where they fulfil an important role in breaking down decaying plant material , although a few live in grasslands, semi-arid habitats or even deserts Myriapod. Britannica Concise Encyclopedia.. The majority are herbivorous, with the exception of centipedes, which are chiefly nocturnal predators. Pauropodans and symphylans are small, sometimes microscopic animals that resemble centipedes superficially and live in soils. Millipedes differ from the other groups in having their body segments fused into pairs, giving the appearance that each segment bears two pairs of legs, while the other three groups have a single pair of legs on each body segment.
Although not generally considered dangerous to humans, many myriapods produce noxious secretions (often containing benzoquinones) which can cause temporary blistering and discolouration of the skin Strange and Unusual Millipedes. herper.com. Retrieved on 2007-07-02..
The fossil record of myriapods reaches back into the late Silurian, although molecular evidence suggests a diversification in the Cambrian Period Markus Friedrich & Diethard Tautz (2002). Ribosomal DNA phylogeny of the major extant arthropod classes and the evolution of myriapods. Nature 376: 165–167. doi:10.1038/376165a0. , and Cambrian fossils exist which resemble myriapods .
Contents |
There has been much debate as to which arthropod group is most closely related to the Myriapoda. Under the Mandibulata hypothesis, Myriapoda is the sister taxon to Pancrustacea, a group comprising the Crustacea and Hexapoda. Under the Atelocerata hypothesis, Hexapoda is the closest, whereas under the Paradoxopoda hypothesis, Chelicerata is the closest. This last hypothesis, although supported by few, if any, morphological characters, is supported by a number of molecular studies Alexandre Hassanin (2006). Phylogeny of Arthropoda inferred from mitochondrial sequences: strategies for limiting the misleading effects of multiple changes in pattern and rates of substitution. Molecular Phylogenetics and Evolution 38: 100–116. doi:10.1016/j.ympev.2005.09.012. .
Scolopendra cingulata, a centipede
Scutigerella immaculata, a symphylan
Pauropus huyxleyi, a pauropodan
There are four classes of extant myriapods, Chilopoda (centipedes), Diplopoda, Pauropoda and Symphyla, containing a total of around 12,000 species A. D. Chapman (2005). Numbers of Living Species in Australia and the World. Department of the Environment and Heritage. ISBN 0-642-56850-2. . While each of these groups of myriapods is believed to be monophyletic, relationships among them are less certain Jerome C. Regiera, Heather M. Wilson & Jeffrey W. Shultz (2005). Phylogenetic analysis of Myriapoda using three nuclear protein-coding genes. Molecular Phylogenetics and Evolution 34: 147–158. doi:10.1016/j.ympev.2004.09.005. .
Centipedes make up the order Chilopoda. They are fast, predatory and venomous, hunting mostly at night. There are around 3,300 species , ranging from the diminutive Nannarup hoffmani (less than half an inch in length, c. 12 mm) "Central Park survey finds new centipede", American Museum of Natural History, 2003-01-29. to the giant Scolopendra gigantea, which may exceed 30 cm (12 in).
Most millipedes are slower than centipedes, and feed on leaf litter and detritus. They are distinguished by the fusion of each pair of body segments into a single unit, giving the appearance of having two pairs of legs per segment. Around 8,000 species have been described, which may represent less than a tenth of the true global millipede diversity . One species, Illacme plenipes has the greatest number of legs of any animal, with 750 . Pill millipedes are much shorter, and are capable of rolling up into a ball, like pillbugs.
About 200 species of symphylans are known worldwide . They resemble centipedes but are smaller and translucent. Many spend their lives as soil infauna, but some live arboreally. Juveniles have six pairs of legs, but, over a lifetime of several years, add an additional pair at each moult so that the adult instar has twelve pairs of legs Garden Symphylans. Integrated Pest Management on Peppermint-IPMP3.0. Oregon State University. Retrieved on 2007-07-02..
Pauropoda is another small group of small myriapods. They are typically 0.5–2.0 mm long and live in the soil on all continents except Antarctica Pauropods: Pauropoda. Insects and Spiders Scientific Reference. Retrieved on 2007-07-02.. Over 700 species have been described . They are believed to be the sister group to millipedes, and have the dorsal tergites fused across pairs of segments, similar to the more complete fusion of segments seen in millipedes David Kendall (2005-06-06). Pauropods & Symphylids. Kendall Bioresearch..
Wikibooks\' Dichotomous Key has more about this subject:
Wikispecies has information related to:
Wikimedia Commons has media related to:
This article is licensed under the GNU Free Documentation License. It uses material from Wikipedia
 3.jpg/58px-Steinläufer (Lithobius forficatus) 3.jpg)