AskDefine | Define millipede

Dictionary Definition

millipede n : any of numerous herbivorous nonpoisonous arthropods having a cylindrical body of 20 to 100 or more segments most with two pairs of legs [syn: millepede, milliped]

User Contributed Dictionary

English

Etymology

milli-, thousand, + pede, foot

Noun

  1. Any of many elongated arthropods, of the class Diplopoda, with cylindrical bodies that have two pairs of legs for each one of their 20 to 100 or more body segments.

Translations

Extensive Definition

Millipedes (Class Diplopoda, previously also known as Chilognatha) are arthropods that have two pairs of legs per segment (except for the first segment behind the head which does not have any appendages at all, and the next few which only have one pair of legs). Each segment that has two pairs of legs is a result of two single segments fused together as one. Most millipedes have very elongated cylindrical bodies, although some are flattened dorso-ventrally, while pill millipedes are shorter and can roll into a ball, like a pillbug. Millipedes are detritivores and slow moving. Most millipedes eat decaying leaves and other dead plant matter, moisturising the food with secretions and then scraping it in with the jaws. However they can also be a minor garden pest, especially in greenhouses where they can cause severe damage to emergent seedlings. Signs of millipede damage include the stripping of the outer layers of a young plant stem and irregular damage to leaves and plant apices.
This class contains around 10,000 species. There are 13 orders and 115 families.
The giant African millipede (Archispirostreptus gigas) is the largest species of millipede. Millipedes can be easily distinguished from the somewhat similar and closely related centipedes (Class Chilopoda), which move rapidly, and have a single pair of legs for each body segment.

Prehistory

This class of arthropod is thought to be among the first animals to have colonised land during the Silurian geologic period. These early forms probably ate mosses and primitive vascular plants. The oldest known land creature, Pneumodesmus newmani, was a 1 centimetre-long millipede.

Characteristics

The millipede's most obvious feature is its large number of legs. In fact, its name is a compound word formed from the Latin roots milli ("thousand") and ped ("foot"). Despite their name, these creatures do not have a thousand legs, although the rare species Illacme plenipes have up to 750 . However, common species have between 80 and 400 legs.
Having very many short legs makes millipedes rather slow, but they are powerful burrowers. With their legs and body length moving in a wavelike pattern, they easily force their way underground head first. They also seem to have some engineering ability, reinforcing the tunnel by rearranging the particles around it.Their bodies have segmented sections which makes them move in a wave like form.
The head contains a pair of sensory organs known as the Tömösváry organs. These are found just posterior and lateral to the antennae, and are shaped as small and oval rings at the base of the antennae. They are probably used to measure the humidity in the surroundings, and they may have some chemoreceptory abilities too. Millipede eyes consist of a number of simple flat lensed ocelli arranged in a group on the front/side of the head. Many species of millipedes, such as cave-dwelling millipedes, have secondarily lost their eyes.
Male millipedes can be differentiated from female millipedes by the presence of one or two pairs of legs modified into gonopods. These modified legs are used to transfer sperm packets to the female during copulation.
In very rare instances, a millipede may be amphibious.
According to Guiness World Records the African Giant Black Millipede can grow to 38.6cm (15.2 in).

Defense mechanisms

Due to their lack of speed and their inability to bite or sting, millipedes' primary defense mechanism is to curl into a tight coil — protecting their delicate legs inside an armoured body exterior. Many species also emit poisonous liquid secretions or hydrogen cyanide gas through microscopic pores along the sides of their bodies as a secondary defense . Some of these substances are caustic and can burn the exoskeleton of ants and other insect predators, and the skin and eyes of larger predators. Lemurs have been observed intentionally irritating millipedes in order to rub the chemicals on themselves to repel insect pests, and possibly to produce a psychoactive effect.
As far as humans are concerned, this chemical brew is fairly harmless, usually causing only minor effects on the skin, the main effect being discoloration, but other effects may also include pain, itching, local erythema, edema, blisters, eczema, and occasionally cracked skin . Eye exposures to these secretions causes general eye irritation and potentially more severe effects such as conjunctivitis and keratitis . First aid consists of flushing the area thoroughly with water; further treatment is aimed at relieving the local effects.

Classification

The Class Diplopoda is divided into fifteen orders in three subclasses . The subclass Penicillata contains 160 species millipedes whose exoskeleton is not calcified, and which are covered in setae or bristles. The subclass Pentazonia contains the short-bodied pill millipedes, which are capable of rolling themselves into a ball (volvation). The subclass Helminthomorpha contains the great majority of the species .

Gallery

This is a picture of an ancient millipede.

References

millipede in Catalan: Milpeus
millipede in Danish: Tusindben
millipede in German: Doppelfüßer
millipede in Esperanto: Milpieduloj
millipede in Spanish: Diplopoda
millipede in French: Diplopoda
millipede in Hebrew: רב רגליים
millipede in Ido: Miriapodo
millipede in Italian: Diplopoda
millipede in Japanese: ヤスデ
millipede in Lithuanian: Dviporiakojai
millipede in Latvian: Tūkstoškāji
millipede in Malayalam: തേരട്ട
millipede in Malay (macrolanguage): Gonggok
millipede in Dutch: Miljoenpoten
millipede in Norwegian: Tusenbein
millipede in Occitan (post 1500): Diplopoda
millipede in Polish: Dwuparce
millipede in Portuguese: Diplópode
millipede in Romanian: Milipede
millipede in Russian: Многоножки
millipede in Simple English: Millipede
millipede in Sundanese: Titinggi
millipede in Swedish: Dubbelfotingar
millipede in Thai: กิ้งกือ
millipede in Tagalog: Millipede
millipede in Chinese: 馬陸
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